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THE CHEMISTRY
AXD
TECHNOLOGY OF PAINTS
By MAXIMILIAN TOCH
11727/ S3 PHOTOMICROGRAPHIC PLATES
AND OTHER ILLUSTK-ITIO.VS
SECOND REVISED EDITION
NEW YORK
D. VAN NOSTRAND COMPANY
1916
r
782555
1 ■ ' ■ i
• .. 1 ■; L j
COPYRIGHT, 1907, BY
D. VAN NOSTRAND COMPANY
COPYRIGHT, 191 6, BY
D. VAN NOSTRAND COMPANY
• • •
• • ••
• • • •
• •• •
• ••
•.•
m
• •••'
- . • •••• ••'•
• ••• :. ••:;•••
••• -
• • •
THE-PLIMPTOS'PRKSS
N O R W O o D • M A S S • I- • S • A
PREFACE TO FIRST EDITION
The difficulty which I encountered in writing this
book was not how much to write but how much to omit,
for I found on compiling my notes that I could very
easily have made two volumes, each larger than the
present one, and still would not have covered the ground
thoroughly. It is for this reason that I have omitted
many of the pigments which are rarely used, and have
paid no attention whatever to the pigments which have
gone out of use.
I have not considered it desirable to use any space in
this book with extended repetition o^ matter that can be
found in other books of reference, for I have so much
matter which is the result of original research that very
few references are cited.
This being the first book ever written on the subject
of mixed paints, I am cognizant of the fact that there
are many matters in it which I shall have to alter in
future editions, and many subjects upon which I shall
have to enlarge. It must be borne in mind that mixed
paint is demanded by a progressive civilization and that
there are no two manufacturers who make identically the
same mixtures. As time changes, the progressive manu-
facturer alters his formulas, and an indication of this is
that the original mixed paints were mostly emulsions
and soap solutions, whereas today the tendency is toward
purity and improvement, and one manufacturer tries to
outdo the other in making a paint that will last, the
ideal paint, however, being never reached.
3
(.
4 PREFACE TO FIRST EDITION
This volume is intended for the student in chemistry
who desires to familiarize himself with paint, or the
engineer who desires a better knowledge of the subject,
or for the paint manufacturer and paint chemist as a
work of reference. It is not intended for those who have
no previous knowledge or training in the subject.
Some of the chapters in this book are taken from my
lectures delivered at various universities, and others are
extracts from lectures delivered before scientific bodies.
One of the objects which I have had in view during the
entire time I have been writing this book is to familiarize
the student in chemistry, or the post-graduate, with the
science and technology of modem paints, so that in a
very short time the chemist unfamiliar with the subject
may obtain sufficient knowledge to make a reasonable
examination of paint.
The chapter on linseed oil illustrates this, and my
researches and theories on the difference between raw
and boiled linseed oil are here' pubHshed for the first time.
From the formulas and disquisition on the subject it
can be easily seen that if raw linseed oil be taken as a
standard nearly all comparisons fail if boiled linseed oil
is under examination.
320 Fifth Avenue
New York, 1907
PREFACE TO SECOND EDITION
Since the first edition of this book was published the
efforts of a large number of technical men working in this
field have resulted in very important advances both in the
production of new pigments, oils and special paints and in
the scientific elucidation of many obscure phenomena in
paint technology. Improvements have also been made in
the method of manufacture as well as in the quality of
many of the older pigments. Advances have also been
made in the discovery and utilization of a number of oils
which have not heretofore found extended use in the paint
trade.
These important advances have necessitated rewriting
most of the book and the addition of new matter to the ex-
tent of doubling its size. Some of the important additions
which may be worthy of mention are, standard specifica-
tions for pigments and oils; new special paints and driers;
the theory of corrosion of iron and steel and its prevention
as well as the action of fungi on paints; the important sub-
ject of the hygiene of workmen ; detailed methods of analy-
sis of paints and paint materials as well as tables of
constants of such materials.
Undoubtedly the chemical manufacturer and the chemical
student who intends to become proficient in paint chemistry
will find it essential to read a great deal of the past as well
as the current technical literature of the subject, but it is
the hop)e of the author that this hook will give the student
a comprehensive survey of the progress already made and
furnish a foundation for further improvement.
MAXIMILIAN TOCH
320 Fifth Avenue
New York
July, 1916 e
CONTENTS
Preface to First Edition 3
Preface to Second Edition 5
Introduction 13
CHAPTER I
The Manufacture OF Mixed Paints 18
CHAPTER n
The White Pigments 26
White Lead. — Sulphate of Lead. — Sublimed White Lead. —
Standard Zinc Lead White. — Ozark White. — Zinc Oxid. —
Zinox. — Lithopone.
CHAPTER III
The Oxids of Lead 53
Litharge. — Red Lead. — Blue Lead.
CHAPTER IV
The Red Pigments 62
Venetian Reds. — Indian Red. — Permanent Vermilion. — Helio
Fast Red. — Lithol Red.
CHAPTER V
The Brown Pigments 71
American Burnt Sienna. — Italian Burnt Sienna. — Burnt Umber.
— Burnt Ochre. — Princess Metallic or Princess Mineral Brown.
— Vandyke Brown.
8 CONTENTS
CHAPTER VI
The Yellow Pigments 78
American Yellow Ochre. — French Yellow Ochre. — Chrome Yel-
low. — Chromate of Zinc.
CHAPTER Vn
The Blue Pigments 84
Ultramarine Blue. — Artificial Cobalt Blue. — Prussian Blue.
CHAPTER VIII
The Green Pigments 92
Chrome Green* -^ Chromium Oxid. — Green Aniline Lakes. —
Zinc Green. — Verte Antique (Copper Green).
CHAPTER IX
The Black Pigments 97
Lampblack. — Carbon Black. — Graphite. — Charcoal. — Vine Black.
— Coal. — Ivory Black. — Drop Black. — Black Toner. —
Benzol Black. — Acetylene Black. — Mineral Black.
CHAPTER X
The Inert Fillers and Extenders no
Barytes. — Artificial Barium Sulphate. — Barium Carbonate. —
Silica. — Infusorial Earth. — Kieselguhr. — Fuller's Earth. —
Clay. — Asbestine. — Asbestos. — Calcium Carbonate. — White
Mineral Primer. — Marble Dust. — Spanish White. — Artificial
Calcium Carbonate. — G)rpsum.
CHAPTER XI
Mixed Paints 140
Anti-fouling and Ship's Bottom Paints. — Concrete or Portland
Cement Paints. -^ Paint Containing Portland Cement. — Damp-
Resisting Paints. — Enamel Paints. — Flat Wall Paints. — Floor
Paints. — Shingle Stain and Shingle Paint.
CHAPTER XII
Linseed Oil 158
Linseed Oil. — Standard Specifications, American Society for Testing
Materials for Linsc»ed Oil. — U. S. Navy Department Specifica-
tions for Linseed Oil. — Stand Oil. — Japanner's Prussian Brown
on.
r
CONTENTS 9
CHAPTER XIII
Chinese Wood Oil i8o
Chinese Wood Oil — A Method for the Detection of Adulteration
of China Wood Oils. — Standard Specifications American Society
for Testing Materials for Purity of Raw Chinese Wood Oil.
CH.\PTER XIV
Soya Bean Oil 192
CHAPTER XV
Fish Oil 203
CHAPTER XVI
Miscellaneous Oils 210
Herring Oil. — Corn Oil.
CHAPTER XVII
Turpentine 217
Turpentine. — Wood Turpentine. — Standard Specifications Ameri-
can Society for Testing Materials for Turpentine. — U. S. Navy
Department Specifications for Turpentine.
CIL\PTER XVIII
Pine Oil 228
CHAPTER XIX
Benzine 238
CHAPTER XX
Turpentine Substitutes 243
Benzol. — Toluol. — Xylol. — Solvent Naphtha.
CIL\PTER XXI
Cobalt Driers 247
lO CONTENTS
CHAPTER XXII
Combining Mediums and Water 254
Combining Mediums. — Water in the Composition of Mixed Paints.
CHAPTER XXIII
Fine Grinding 259
CHAPTER XXIV
The Influence of Sunught on Paints and Varnishes .... 261
CHAPTER XXV
Paint Vehicles as Protective Agents Against Corrosion . . . 266
CHAPTER XXVI
The Electrolytic Corrosion of Structural Steel 276
CHAPTER XXVII
Painters' Hygiene 281
CHAPTER XXVIII
The Growth of Fungi on Paint. 284
Analysis of Paint Materials 288
White Lead. — Basic Lead Sulphate. — Zinc Lead. — Zinc Oxid. —
Lilhopone. — Red Lead and Orange Mineral. — Iron Oxids. —
Umbers and Siennas. — Mercury Vermilion. — Chrome Yellows
and Oranges. — Chrome Greens. — Prussian Blue. — Ultra-
marine. — Black Pigments. — Graphite. — Blanc Fixe. —
Whiting. — GjTDsum or Calcium Sulphate. — Silica. — Asbes-
tine. — Clay. — Barytes. — Barium Carbonate. — Mixed
White Paints. — White Pigments. — Paints. — Rosin. —
Rosin Oils. — Oils. — Etc., Etc.
CONTENTS II
APPENDIX
Some Characteristics and Variables of Commercial Boiled
Oils 343
Characteristics of Boh-ed Oils (Lewkowitsch) 343
CON\-ERSION OF FRENCH (MeTRIC) INTO ENGLISH MEASURE. . . 344
C0NVT.RS10N OF French (Metric) into English Weight . . . 344
Metric System of Weights and Measures 345
Specific GRAvirv of Various Materials 346
Specific Gravity of the Elements 350
Pounds of Oil Required for Grinding 100 Pounds Various
Dry Pigments into Average Pastes 350
Specific Gravity of Various Woods 351
Table Showing the Comparison of the Readings of Ther-
mometers 352
International Atomic Weights 353
List of Photomicrographs 355
Index 357
THE CHEMISTRY
AND
TECHNOLOGY OF PAINTS
INTRODUCTION
The manufacture of mixed paints is essentially
American, ha\dng been accredited to some enterprising
New Englanders who observed that when a linseed oil
paint was mixed with a solution of silicate of soda (water
glass) an emulsion was formed, and the paint so made
showed very little tendency to settle or harden in the
package. Several lay claim to this discovery. The
first mixed paint was marketed in small packages for
home consumption and appeared about 1865.
The addition of silicate of soda is still practised by a
few manufacturers, but the tendency is to eliminate it
as far as possible and to minimize as much as possible
the use of an alkaline watery solution to keep the paint
in suspension. The general use of zinc oxid has had
much to do with the progress of mixed paint, for it is
well known that corroded white lead and linseed oil
settle quickly in the package, while zinc oxid keeps the
heavier lead longer in suspension. Where only hea\y
materials are used, manufacturers are inclined to add
up to 4 per cent of water. Under another chapter on
"Water in the Composition of Mixed Paints,'' page 254,
this subject will be fully discussed.
To the pigments are added many materials possessing
but little body, hiding or covering property, which are
13
14 INTRODUCTION {
known as inert fillers, and some of these, partictdarly
the silicates of alumina and the silicates of magfcesia,
the various calcium carbonates, and silica itself, are ^ used
to counterbalance the heavy weight or the specific gravity
of the metallic pigments; and whereas these inert fillers
were formerly regarded as adulterants and cheapening
agents, they are now looked upon as necessities, and the
consensus of opinion among practical and many scientific
investigators is that a compound paint composed of lead,
zinc, and a tinting pigment, to which an inert material
has been added, is far more durable than paint made of
an undiluted pigment. The consuming public and the
painter himself have not been sufficiently educated as yet
to understand the merits of these diluents, and the paint
manufacturer has been reticent in his statements regard-
ing the use of various fillers.
These facts account to a large degree for the opposi-
tion to the use of such materials. When it is taken
into consideration that within forty years the sale of
mixed paints in the United States has grown to almost
sixty million gallons per year (and the outlook is for a
larger increase in the use of mixed paints), it is obvious
that the demand is healthy, even though the manufacture
of mixed paints has been directed or based largely upon
empirical formulas.
One of the railroads of the United States buys at this
writing upward of one million dollars' worth of paint
material per year, a large share of this being mixed paints,
or paint ready for the brush. Nearly all of the large
manufacturing industries which use large quantities of
paint are gradually altering their methods, so that their
paint comes to them ready for application. In no case,
to the best knowledge of the author, does a single one
of these industries prescribe a single pigment with linseed
y
INTRODUCTION 15
oil for general purposes, for it has been shown that a
mixture of several pigments and a filler is superior from
the standpoint of lasting quality and ease of application
to a mixture of a single strong pigment and the vehicle.
The structural iron industry, which has reached an
enormous development in the United States, uses paints
ready mixed with the one exception of red Jead, which, in
the old prescription of thirty-three pounds of red lead to
one gallon of oil, cannot be prepared ready for the brush,
for reasons which will appear in the proper chapter.
The manufacture of agricultural implements, wagons,
and wire screens can be cited as industries in which manu-
facturers have within a ver>' few years adopted the use
of ready-mixed paints for their products. These paints
are not brushed on, but are so scientifically made, and
the relation between a vehicle and a pigment is so
carefully observed, that large pieces of their products can
be dipped into troughs and the paint allowed to drain.
The surface is more evenly coated and the work done in
far less time than would be required were it applied
by means of the brush, as in former years.
In \dew of all these facts, the prejudice on the part
of the general pubUc and the trepidation of the manu-
facturer are to blame for the unheralded knowledge of
the constituents of mixed paints. There are many cases
where materials which were once despised are regarded
now as essential to the life and working quality of paint,
and the attitude of the paint manufacturer must in
the future be a frank and open admission of the com-
position of his materials. If a paint is composed of a
mixture of white lead, zinc oxid, and bar>'tes, and it has
been proved that a mixture of these three will outlast
a mixture of either of the other two, there is no reason
why a manufacturer of mixed paints shall not so state.
Vv
l6 INTRODUCTION
New materials have come into use which have taken
the place in a large degree for many purposes of the
time-honored and- useful white lead, and many mixed
paint manufacturers have already begun to educate the
public to the superiority of one material over another.
It stands to reason, however, that the manufacturer of
a raw material which has been in use for a very long
time is going to refute as much as possible the statement
made with regard to newer materials, and these dis-
cussions tend to do good rather than harm.
In the case of one of the large railroads, the speci-
fications for a certain paint demand the use of over 70
per cent of inert filler, and if these inert fillers had no
merit no railroad or large corporation would permit their
use. These large corporations support chemical labora-
tories and employ the best talent which they can engage.
They continually experiment, and in their specifications
the results of their experiments are obvious, and there-
fore if a large corporation can state publicly not only
what the composition of these paints shall be, but con-
clude that such compositions are based upon the results
of scientific investigation, the paint manufacturer can
do likewise and stand back of his products, provided they
be mixtures of various materials which time, science,
and investigation have proved to be superior.
Unfortunately, however, there are some manufactur-
ers who have "hidden behind a play of words" and per-
mit chicanery and finesse to enter into the description
of their products; but fortunately some of them have
seen the errors of their way, and already there is a ten-
dency toward openness and candor with regard to their
wares. There was a time, and it still exists in a measure,
when substitutes for white lead were very largely sold,
and misleading labels appeared on the packages; for
INTRODUCTION 17
instance, a man would make a mixture of 80 per cent
barytes and 20 per cent white lead, and would print
on the label — "The lead in this package is guaranteed
absolutely pure,'' followed by a commendation and
guarantee that certain sums of money would be paid if
the lead were not found to be pure. This, of course, is
a moral fraud and an unfortunate play on the ambiguity
of the language, and many of the manufacturers, in view
of such unfortunate misstatements, are altering the
names of their paste products, or lead substitutes,
omitting the word "lead" entirely.
Another unfortunate mistake is made when a manu-
facturer makes a mixed paint and states on the label,
"This paint is composed of pure lead, pure zinc, pure
linseed oil, pure drier, and nothing else/' The analyses
of the paint have proved that in addition to the "pure"
products mentioned three gallons of water were added
to every hundred gallons of paint in order to keep the
paint in suspension, and that it had not been strained
and therefore contained a large amount of dirt and for-
eign matter. Ethics would clearly indicate that no
manufacturer has a moral right to label his paint as
being entirely pure and composed of four materials,
when as a matter of fact an excessive quantity of water
was added which destroyed in a large degree the value
of the other materials. In another chapter the question
of the percentage of water which may be contained in
any paint will be thoroughly discussed. Three per cent
is entirely excessive in an exterior linseed oil paint, and
a manufacturer has no right, either morally or legally,
to hide behind a misrepresentation of his paint when
the paint is largely adulterated for the purpose of over-
coming his ignorance in the manufacture.
CHAPTER I
The Manufacture of Mixed Paints
The modem methods of making mixed paint are
di\dded into two classes, which depend upon the specific
gravity and fineness of the raw material.
One of the methods employed is to mix the raw
material with sufficient linseed oil to form a very heavy
paste, the proper tinting material being added during
the process of mixing. This paste is then led down
from the floor on which it is made into a stone mill and
ground. Even when the mill is water-cooled, the mass
frequently revolves at such a speed that the paste paint
becomes hot. It is then allowed to run from the mill
into a trough called the "cooler," or is stored in barrels
to be thinned at some later time. In case the operation
is continuous and the paste is thinned at once, it passes
from a stone mill to a mixer below which contains the
requisite quantity of thinning material composed of oil,
volatile thinner, and drier, where it is intimately mixed
by means of paddles. It is then compared with the
standard for shade, and if the tone should not be identical
with the former mixing, either tinting material or pigment
is added in sufficient amount to produce • the proper
shade. From the last mixer, knowTi as the "liquid
mixer," the paint is drawoi off and filled into packages,
the final operation before allowing it to enter the package
being to strain it. This method has been used ever
since mixed paints have been made. The majority of
i8
THE MANUFACTURE OF MIXED PAINTS 19
white paints, or paints of heavy specific gravity, are
made in this manner.
The paints of lower specific gravity, varnish and
floor paints, are made differently. This method is really
the reverse of the old-fashioned method, in that the
liquid and pigment are placed in a mixer on an upper
floor in the amounts necessarj^ to produce the correct
consistency. The paint is run down in a thin stream to
the floor below into a mill knowoi as the *^ liquid mill."
The liquid mills revolve very rapidly, the stones being
flat.
According to the best practice of making paste
paints a grinding surface is supposed to be conical,
although there is much difference of opinion on this
subject. When the paint has run through the stones of
a liquid mill, it comes out of a spout and is then ready
for packing, due precaution being taken, however, to
strain it twice, once as it passes down into the liquid
mill and again as it flows out. There is much difference
of opinion among paint-making mechanics as to the
proper surface which a grinding surface shall present;
for instance, the first depression in the stone of a mill
is deep, tapering toward the edge, and is known as the
''lead.'' From the end of this *^lead'' fine lines radiate
toward the "periphery'' of the stone. These are called
the "drifts," and the paints containing silica wear off
the surface of even the hardest flintstone mills, so that
in well-regulated factories a man is always employed
sharpening the mills, and by the term "sharpening" is
understood cutting out the "drifts" and "leads."
Not so many years ago paint mills were composed
of either iron or steel, but in modem paint practice mills
of this character have been abandoned, except for use
as filling machines. They grind fairly fine when sharp.
1.
20 CHEMISTRY AND TECnNOLOGY OF PAINTS
but inasmuch as all silicious paint materials are harder
than steel or iron they become dull in a very short time.
Then again, the attrition grinds off small particles of
iron, which affect all delicate tints more or less.
The arrangement of the tanks and mills in the factory
is of the greatest importance. Taking up first the
second method of mixing paint already described, the
liquid and white base are mixed in large, heavy cast-
iron mixers, which are located on a platform high
enough to discharge into a liquid mill. (See Fig. i,
Heavy Mixers.)
The mixed material is ground through this mill and
discharged from it into storage tanks situated con-
veniently on a platform below the floor on which the
mill is located, these storage tanks holding from 1500
to 2000 gallons of the ground product. From the stor-
age tanks a pipe-line with its various branches carries
the paint to tinting tanks placed at convenient dis-
tances from the storage tanks, the latter being high
enough to allow the paint, by gravity, to flow through
pipes to the tinting mixers. This pipe-line is made of
wrought iron, the usual diameter of which is 4 inches,
the joints being all flanged so that the pipes may be
easily taken apart and cleaned.
Underneath the storage tanks and close to the outlet
is a master valve, so that the product in the tank may be
shut off at any time and the flow cut out from the sys-
tem of pipes. Opposite each tinting tank (these tanks
should be in parallel rows and numbered to correspond
to the tints that are to be made) a 2-in. branch pipe is
connected to the 4-in. main, and each of these branches
is furnished with a valve to control the discharge into
the tinting mixers. The cast-iron mixers already men-
tioned should be so arranged that two mixers work in
THE MAXUFACTIRE OF MIXF.D PAIXTS 21
conjunction with one mill. The mill is of stone and
known as a liquid or incased mill, the usual diameter
being 30 to 36 inches.
I'm. 1 — Heavy !Mixi:ks
The storage tanks are made of sheet metal with
hea\'y sheet-steel bottoms, and are furnished with a
slowly revolving stirrer to keep the ground liquid agi-
tated. The outlet of these tanks is of generous size and
covered with a steel wire screen to prevent any foreign
fnr
\:' ]
-M
■^^-^
THE MANUFACTURE OF MIXED PAINTS 23
matter such as chips of wood or like material from getting
into the supply pipes. Fastened to the stirrer of these
tanks is a wire brush which scrapes the surface of the
screen in its rotation around the tank, thus keeping the
holes of the screen free for the proper flow of the liquid.
The tinting colors used in this process are usually ground
through small stone mills of 15 in. or 20 in. diameter,
and are stored in convenient portable receptacles.
This method of liquid paint-making reduces the
handling and labor cost to a minimum, the hardest work
being done on the mixer platform where the dry pigment
and the proper amount of liquid are first mixed. In a
factory where the floors are not arranged so that the
method already described can be carried through by
gravity alone, it is possible and practicable to introduce
a force pump, preferably of the rotary type, to make up
for this deficiency. When this latter method is used,
the cast-iron mixer and mill should remain in the same
relative position as before, but the storage tank could be
placed in any other part of a building and on the same
floor as the liquid mill, but high enough to discharge
by gravity into the tinting mixers. The ground pig-
ment would then be discharged into a small tank
situated at the foot of the mill, to which the rotary pump
is attached. As this tank is filled with the ground
product, the pump would force it through the proper
pipe connection to the storage tank, the connection
from the storage tanks to the tinting mixers being the
same as in the first described process.
The other method in use is to mix and grind the
pigment in paste form, using the same style of mixer;
but instead of a hquid mill a paste mill is used. Situated
at the back of this paste mill, and close to the discharge
scraper, is a steel tank of generous dimensions (usually
CHEMISTRY AND TECHXOLOCY OF PAINTS
THE MANUFACTURE OF MIXED PAINTS 25
500 gallons), into which the ground pigment is dis-
charged. This steel tank is provided with a stirrer for
mixing the ground pigment with the oil and other thin-
ners that are added to it, in order to reduce it to a
liquid form. It is then carried to the tinting tanks by
a pipe-line on the same general plan as that heretofore
described.
One of the advantages of this plan is that this outfit
can be used in a dual capacity, i.e. it can be used for
the mixing of liquid paints after the plan described and,
by changing the scraper from the back to the front of
the mill, the outfit can be changed into a paste-grinding
plant.
THE PIGMENTS
CHAPTER II
The White Pigments
The white opaque pigments used in making mixed
paints are white lead, zinc oxid, sublimed white lead,
leaded zincs, lithopone, and other zinc and lead
pigments.
Among the white leads there are several varieties;
the principal ones, however, are the old Dutch process
lead and the quick process lead, both of which are
hydrated carbonates of lead.
There are many varieties of zinc oxid made in the
United States, depending largely upon the raw material.
The grade made principally from spelter, according to the
French process, is known in America as "Florence Red"
and "Green Seal Zinc." The seals on zinc indicate the
whiteness of color, the green seal being the whiter. In
Germany the colored seals extend to a greater range
than in America, the green seal being the whitest, the
red next, the blue next, the yellow next, and then the
white.
The New Jersey zinc oxids are made direct from the
ore and are almost as pure as the zincs made from the
metal, but they have a totally different tone, being much
more of a cream color than the so-called French zincs.
The Mineral Point zincs made in Wisconsin contain
a varying percentage of sulphate of lead. The leaded
zincs of Missouri are analogous in composition to those
WHITE PIGMENTS 27
of Mineral Point, but the percentage of sulphate of lead
is much higher.
The standard zinc lead white of Colorado contains
50 per cent oxid of zinc and 50 per cent sulphate of
lead. Sublimed white lead is made in Joplin, Missouri,
from Galena mineral, and will average 95 per cent
ox>'sulphate of lead and 5 per cent zinc oxid. This
material has been largely superseded by a white known
as Ozark White, which is described under that heading.
Lithopone is a double precipitate of sulphide of zinc
and sulphate of barium.
These are the opaque white pigments used in the
manufacture of mixed paints. It is not wthin the power
of any man to say which one of these is the best, because
under certain circumstances one material will outrank
another, and long practice has demonstrated that no
single white pigment material is as good as a mixture of
various white pigments for mixed paint. The differences
of opinion and conflicting reports that one hears con-
cerning these raw materials are largely due to competi-
tion among manufacturers. Whenever a new material
is exploited a manufacturer of a tried and staple pig-
ment naturally finds the defects in the new material
and informs his salesmen to this effect. And so when a
material finally succeeds and takes its place among the
recognized list of pigments it has gone through all the
hardships and \acissitudes possible.
For two thousand years, more or less, there was no
other white pigment than white lead. Within the life-
time and memory of many a paint manufacturer in the
United States all the pigments described in the beginning
of this chapter have been bom and have prospered.
The great competitor of white lead is zinc oxid, and the
weakness of white lead is the strength of zinc oxid, and
28 CHEMISTRY AND TECHNOLOGY OF PAINTS
vice versa. White lead, for instance, is a soft drier and
zinc oxid is a hard drier. White lead finally becomes
powdery; zinc oxid in its eventual drying becomes hard,
and it is for these reasons that a mixture of zinc oxid
and white lead forms such a good combination. On the
other hand, it is regarded as a fact that a paint com-
posed of an opaque white pigment in a pure or undiluted
state should not be used, for experience and chemistry
have both shown that an inert extender added in mod-
erate proportions to the solid white pigment increases
its wearing power, and when the surface finally needs
repainting it presents a better foundation for future
work. Taking all of these facts into consideration, a
paint manufacturer who combines experience with the
teaching of chemistry is quite likely to produce a mate-
rial, that will add both to his reputation and his income.
He Certainly has a great advantage over the man who
works entirely by rule of thumb.
White Lead
Formula, 2PbC03-Pb(OH)2; Specific Gravity, 6.323106.492
White lead is the oldest of all white paints, and prior
to the middle of the last century it was the only white
pigment in use with the exception of a little zinc and bis-
muth. Within half a century quite a number of -other
white pigments have come into use, and only gradually
have the defects of white lead become known. However,
paint manufacturers in the United States are very large
users of dry white lead, which, together with zinc,
asbestine, and other inert materials, forms the bases or
pigments of the mixed paints. There seems to be an
antagonism against the use of white lead which apparently
is unfounded, for, although white lead may have its
WHITE PIGMENTS 29
defects, there is no other white pigment which is loo
per cent perfect, and therefore it is only fair to give that
time-honored material its proper due. White lead as a
priming coat on wood, particularly when it contains
more oil than should normally be used, cannot be ex-
celled.
The history of this pigment, its method of manu-
facture, and the general uses to which it has been applied
are so well known, and are
generally given even in
elementary text-books on
chemistry, that it is not
the author's purpose to
take up much space for
this subject. Briefly stated,
however, there are two
processes for the manu- ,
facture of white lead. One
is called the Dutch process,
which takes about ninety
days and is a slow cor-
rosion of a buckle of lead
in an earthenware pot in the presence of acetic acid.
Carbonic acid froirt fermenting tan bark acts on the
lead, converting the material into hydrated carbonate
of lead. In the other, which is called the quick
process, the acetic acid solution is directly acted upon
by Qither carbonic acid gas or an alkaline carbonate
salt. Th^ old Dutch process is stUI much more largely
used than the quick process, the resulting product being
much more desirable from the practical standpoint.
There are a number of other processes under a variety
of names, but none of them differ \'ery much from the
so-called "quick process."
o. I. CoHHODED WsiTE LEAD — Pho-
tomicrograph X150, of known purity
and composition.
n
^:-n :
30 CHEMISTRY AND TECHNOLOGY OF PAINTS
White lead is in great favor with the practical painter,
not for its wearing quahty, but principally for the free-
dom with which it is applied. Although white lead is
generally spoken of as a carbonate of lead, it is com-
posed of approximately 69 per cent carbonate of lead,
PbCOj, and 31 per cent of lead hydroxid, Pb(OH),,
It is this lead hydroxid which combines quite rapidly
with oil and forms an imctuous substance sometimes
known as "lead soap.''
^^^ White lead is variable in
.£^^ composition, the amount
of hydroxid ranging from
15 to 30 per cent. In
* -'-,'' ■ ■ ■■; '^*: t ■>>■ ' addition to this, during
. *^ -'.*.■■ ■*^'-,*'';' '.A iu ^^^ process of manufac-
"-.''- :V-:'L,>.'^^ ^' ture of the old process
* ' ■•r'''.- :, y^i^^'-'.Vj^:^ lead, and after its final
^fcv^^i, ^*'^\' :;: washing, it is mixed witl
-.. - .'Sir'- ' linseed oil while stiU in
'''''" ' the wet state. The oi]
No. 2. Old Process White Lead — , . ™. •
Ptotomi.ragraph X250. havmg a greater affinity
for the white lead thar
the water has, the latter is displaced. A small per-
centage of moisture adds to the free working quality ol
the paint made from white lead. (See "Water in the
Composition of Mixed Paints," page 255.)
White lead is regarded as a poisonous pigment, and
so it is, but this property should not condemn it foi
application to the walls of a house or for general paint
puqjoses, because its toxic effect cannot be produced
from a painted surface. Its poisonous quality is mani-
fest to the workmen in the factories where white lead is
made, and also to the painter who is careless in apply-
ing it. The unbroken skin does not absorb lead very
WHITE PIGMENTS 31
rapidly, but the workman inhaling lead dust, or the
painter who allows a lead paint to accumulate under his
finger nails, is likely to suffer from lead poisoning. In
one or two factories where much white lead is ground, a
small percentage of potassium iodide is placed in the
drinking water. This overcomes any tendency toward
lead poisoning, by reason of the fact that the soluble
iodide of lead is formed in the system and the lead is
thus flushed out through
the kidneys. Charles Dick- -g*"**-! V^ ^ ji
ens, in one of his short ^^' ■if'^^^rj' *\^*
stories called "A Bright ^^%^ w-^A* *'■'* M-v
Star m the East," com- ; '^■7i-v^y , t''^> ^|^
duced in a certain white »Jt'*^, i ^""i' .•' Ji^ ^ "f ""H
lead factory in London,
and expressed the hope
that American ingenuity
would overcome the dan-
gers which beset the men.
In one of the largest white •"• '■ ^.r^XXso"™' "
lead works in New York
City lead poisoning does not occur, owing to the in-
genuity and care exercised by the management.
The ratio of oil necessary to reduce white lead to the
consistency of paint can by no means be given in exact
figures. The old Dutch process lead will take four and a
half gallons of linseed oil to one hundred pounds of white
lead ground in oil, in order to obtain a paint of maxi-
mum covering property. The new process lead will take
more oil than this, and in many instances up to six
gallons to the one hundred pounds of white lead paste,
which contains approximately ly'ri- gallons of linseed
oil. On a mixed paint basis, 60 pounds of dry white
32 CHEMISTRY AND TECHNOLOGY OF PAINTS
lead will take 40 pounds of linseed oil to produce the
correct ratio, but in addition four pounds of volatile
thinner, such as benzine or turpentine, can be added to
increase the fluidity and assist in the obKteration of
brush marks. No general rule can be given for the per-
centage of oil necessary, as temperature has much to do
wth this, but the difference in the amount of oil neces-
sary to produce a good flowing paint during summer or
winter can be approximately given as 10 per cent, less
vehicle being necessary in summer than in winter.
White lead when exposed to the elements becomes
chalky after a while and assumes a perfectly flat appear-
ance w^hich resembles whitewash, and comes off very
readily on the hand. As long as there was no remedy
for this there was no comment on the subject, but at the
present time investigators have improved paint mixtures
so that this defect is not so palpable as it was in former
years. From many experiments made by the author
the causes of the chalking of white lead may be sum-
marized as follows:
First. The action of the carbonic acid in rain water.
Second. The action of sodium chloride (salt in the air).
Third. The catalytic action of white lead itself in
being a progressive oxidizer of linseed oil.
First. If white lead be treated with water containing
carbonic acid, it is found that the same solvent action
takes place upon carbonate of lead as takes place upon
calcium carbonate.
Second. If white lead be treated wth a sodium or
ammonium chloride solution, a solvent action is apparent,
and its sodium chloride is always present in the air at the
seashore, and carbonic acid is everywhere present in the
atmosi)here and is readily taken up in a rain storm, the
chalking of white lead can be attributed to these causes.
WHITE PIGMENTS 33
Third. This cause is, however, problematical and
cannot at this writing be stated with any degree of
positiveness. It is quite true that white lead and linseed
oil do not attack each other so readily on an interior wall
as they do on a wall exposed to the elements.
One of the defects mentioned by many writers on
white lead is its susceptibility to sulphur gases. In
nature these sulphur gases are generated in two places;
namely, in the kitchen of every house, and in and around
stables and outhouses. In kitchens the cooking of
vegetables liberates hydrogen sulphide to a great extent,
the odor of which is familiar to everybody who comes into
a house where either cauHflower or cabbage is being
cooked. But, inasmuch as undiluted white lead is not
often used for interior painting, the defect is not so
noticeable. A few stables or outhouses are painted pure
white, and when they are painted white the painter
generally has sufficient knowledge of the subject to use
zinc oxid instead of white lead.
It cannot be denied that the ease of appKcation of
white lead, as well as its enormous covering property,
has had much to do with the preference for it as a paint.
With the exception of lithopone, it has a greater hiding
property, volumetrically considered, than any other white
paint; on the other hand, gravimetrically considered, it
has less body than any of the lighter paints.
The addition of an inert filler, such as artificial barium
sulphate, silica, and barytes, improves white lead con-
siderably. These inert fillers, which will be considered
under their proper chapters, are not affected by chemical
influences in the slightest degree, and where they are
used in the proper proportions additional wearing quality,
or "life," as the painter calls it, is given to the paint.
The percentage of inert fillers which can be added to
34 CHEMISTRY AND TECHNOLOGY OF PAINTS
white lead varies up to 50 per cent. More artiQcial
barium sulphate than natural barium sulphate can be
added. If a comparative exposure test be made, both
on wood and metal, of undiluted white lead and white
lead containing an inert extender, it will be found that
at the end of eighteen months the paint which contained
the filler is in a better state of preservation than that
which did not contain it. Generally considered, white
lead is an excellent paint, more particularly when added
to other materials.
Sulphate of Lead
Formula, PbSOi; Specific Gravity, 6.2 to 6.38
It must be borne in mind that the sulphate of lead
of commerce, which is not so frequently met with nowa-
days as formerly, is a very poor paint material, and it
must not by any means be confounded with sublimed
white lead, which is at times erroneously called lead
sulphate.
The lead sulphate of the paint trade is a nondescript
article which was sold as a by-product by the textile
printers who used acetate of lead as a mordant, and to
this liquid sulphuric acid was added and the precipitate
was sold to the paint trade under the name of lead
bottoms or bottom salts. Occasionally this material is
still met with, and wherever it is used in a mixed paint
it does more harm than good. It is likely that the pure
neutral lead sulphate, which is a good oxidizing agent,
dries well, and covers fairly well, could be used for ordi-
nary light tints if diluted with the proper inert materials,
but the lead sulphate which is sold by the textile printers
is always acid and is sometimes coarse and crystalline,
though at other times quite fine. The chemist, the paint
WHITE PIGMENTS 35
maker, and the engineer must never confound this lead
sulphate with the lead sulphate contained in sublimed
lead, zinc lead, or leaded zincs.
Sublimed White Lead
Specific Gravity, 6.2
Sublimed white lead is an amorphous white pigment
possessing excellent covering and hiding power, and is
very uniform and fine in grain. It is a direct furnace-
product obtained by the sublimation of Galena, and
within the last ten years it has come into great prom-
inence among paint makers, now being regarded as a
stable, uniform, and very valuable paint pigment. The
author has examined a great many paints containing
sublimed lead. Among one hundred reputable paint
manufacturers in the United States sixty-five used sub-
limed lead. About eight thousand tons were used in
the United States in 1905. Considering the fact that
sublimed lead as a pigment is about twenty-five years
old, it is very likely, judging from its qualities, that it
will be used more universally and in larger quantities
in the future.
When mixed with other pigments, such as zinc oxid,
carbonate of lead, and the proper reducing materials
added, such as silica^ clay, barium sulphate, etc., it pro-
duces a most excellent paint, and at the seashore its
wearing quality is superior to that of carbonate of lead.
In composition it is fairly uniform. From the analyses
of thirty-four samples of sublimed lead its composition
may be quoted as 75 per cent lead sulphate, 20 per cent
lead oxid, and 5 per cent zinc oxid, although each of
these figures will vary slightly either way. Corroded
white lead also varies in its percentage of hydroxid, but
36 CHEMISTRY AND TECHNOLOGY OF PAINTS
for analytical purposes a constant must be admitted
which will fairly represent the composition.
The question has arisen of late years whether sublimed
lead is a mixture of the three components just cited, or
whether it is a combination of lead sulphate and lead
oxid with the mechanical addition of zinc oxid. Inas-
much as all the lead oxids that are known in commerce
or in chemistry are yellow, red, or brown it is held by
many that the lead oxid
of sublimed lead is really
an oxysulphate, or, in
other words, a basic sul-
**■?*. "k",'' • ."'/' > •* i'' '!'*' pbate of lead. A mixture
ti"'}'j'' .'••"V-** *f'\\^^ precipitated lead sul-
*j.V I ■^. ■^'■,■""'.1 * j^-^.-V J phate, litharge, and zinc
4j> -■.'■'»■ 'f"" ■*'.*■ **■"■;■**** white in approximately the
^■g^",'-'"..'..* j-'-'uVV r^ proportions found in sub-
^'■^ » »'-.^ '*V'"'*''*3^ limed kad, when ground
* ■ .i *J ■"*■' v\^'' in oil and reduced to the
' - ' " proper consistency, dries
No. 4. SuBUMZD vvmTE LEAD-Pho- ^^J^^^ different from sub-
tcimicrograph X2SO, showing great uni-
formity of grain. limed whitc lead; in fact,
sublimed lead when ground
in raw linseed oil takes two days to dry dust free, but the
mixture just cited will dry sufficiently hard for repaint-
ing in twelve hours, because lead sulphate is a fair drier
and lead oxid a powerful one. Yet the oxysulphate, hav-
ing the- same composition, behaves totally differently from
the mixture and in addition is of a different color.
Under the microscope sublimed lead shows the
absence of cr>'Stals and remarkable uniformity of grain.
Being a much more inert chemical body than the other
lead paints, it does not react on linseed oil, and there-
fore makes a much more durable paint compound. It
WHITE PIGMENTS 37
has been urged that sublimed lead is not as susceptible
to sulphur gases as white lead, but this the author
has not been able to substantiate, for while it may take
hydrogen sulphide a longer time to discolor it, it is
simply a question of degree and it is acted upon by sul-
phur gases, although not as quickly as white lead.
Sublimed lead can be determined in a white mixed
paint without any difficulty, owing to the estabKshed
ratio between lead oxid and lead sulphate. The per-
centage of free zinc sulphate in sublimed white lead
varies from a trace to a half per cent, and many times a
chemist will report more zinc sulphate than is actually
present, because in washing or boiling a dry or extracted
sample the lead sulphate may interact with the zinc
oxid and show a larger percentage of zinc sulphate than
is really present in the dry products before analysis.
Sublimed white lead as a marine or ship paint is of
much value, owing to its harcfiiess of drying and imper-
viousness of film.
Standard Zinc Lead White
The ores utilized in the manufacture of this material
are what are known in mining parlance as "Low Grade
Complex Ore," originating in and about Leadville, Colo-
rado; Low Grade, inasmuch as the gold, silver, and cop-
per are present in quantities too small to warrant the
excessive cost of refining. Naturally this ore contains
varying percentages of zinc blende or sphalerite and
Galena or native lead sulphide, and in order to furnish
the product with the proper proportions of lead and zinc
the ores are first analyzed, then mixed in their proper
proportions, and volatilized at a heat of from 2200 to
2500° F. In the volatile state it is carried to the com-
bustion chamber, where the chemical transformation of
38 CHEMISTRY AND TECHNOLOGY OF PAINTS
the product, due to oxidation, completes itself. The
white fume is collected in woolen bags, further oxidized
on open-hearth furnaces, whitened, and then bolted.
The pigment carries approximately 50 per cent pure
zinc oxid and 50 per cent lead sulphate, which have
combined at an intense heat in vapor form, the union
being far more intimate than anything that could be
obtained by mechanical means.
This pigment was first
.:.*J^^^^i^,it.s. P"*- "P**" ^^^ market
]|:'^^'~i>^-^^/^V twenty-four years ago, and
"•* '-r %i..
, Sta,\dard ZfN'c Lead Win
rhotomicrograph X150.
[ period not exceeding ten
I years, and within the last
' eight or ten years it had
become more uniform and
was regarded as a valu-
able paint material by a
great many mixed paint
manufacturers. However,
this material is at pres-
ent not manufactured, but has been largely superseded
by a white known as Ozark White, which will be de-
scribed under that heading.
The color, while it is not as white as zinc oxid, is
about the same shade as the average corroded white
lead. The pigment can be used to great advantage
in combination leads, graded leads, primers, floor paints,
and ready mLxed paints. Its specific gravity is approxi-
mately 5.5, and its composition theoretically 50 per
cent pure zinc oxid and 50 per cent lead sulphate.
The pigment generally contains a trace of silica, iron, and
alumina. A very small portion of the lead is in the
WHITE PIGMENTS 39
form of a basic lead sulphate, and the pigment un-
doubtedly takes up a little moisture on standing. Its
average analysis shows the following composition:
PbS04 50.00 per cent
ZnO 49-55 per cent
ZnS04 0.40 per cent
The percentage of zinc sulphate will vary slightly,
but under normal conditions it will seldom average higher
than ^ of I per cent, and where it does average more than
this it is frequently due to long-continued boiling in the
flask, which causes a reaction between lead sulphate and
zinc oxid.
Analyses of Standard Zinc Lead White
PbSOi 48.90 50.00 49.22 49.80 50.15 48.87
ZnO 50.50 49.55 50.41 49.90 49.25 50.82
ZnS04 0.25 0.40 Trace 0.20 0.12 Trace
Photomicrographs of zinc lead show a uniformity of
grain, and microscopic investigations fail to show anything
but a homogeneous product. It is very stable. When
exposed to the air in a thin film, mixed- with a proper
proportion of linseed oil and drier, it retains its gloss
longer and chalks less than a similar film containing a
mixture of 50 per cent corroded white lead and 50 per
cent zinc oxid. Like white lead, it whitens on exposure,
but holds up in suspension better, as indicated by its
low specific gravity. When a paint is made on a zinc
lead base ground in pure linseed oil it will not separate,
form a cake, or yield a sediment; neither will it peel,
chalk oflF, or turn yellow.
Ozark White
Ozark WTiite is a very desirable pigment and has all
of the good qualities of Standard Zinc Lead White and
40 CHEMISTRY AND TECHNOLOGY OF PAINTS
Sublimed White Lead. It is very largely used .in the
manufacture of mixed paint. In many respects it is
superior to the old Standard Zinc Lead White, because
its approximate composition is 60 per cent of zinc oxid
and ,40 per cent of lead sulphate.
The process is so highly perfected that the manu-
facturers can control the composition so as to insure a
variation of not over 2 per cent, and with rare exceptions
_ the material does not
vary i per cent from the
composition given. To
attain this degree of uni-
formity, a complete anal-
->'.i'j y^s '^^ every car of ore
*-■'-■ -^ is made as soon as it is
received before passing it
to the mechanical mixers.
«..^. At the mixers another
"^ analysis is made, and an
ore higher in zinc or lead
No. 6. Ozark White— Phoiomiciogniph ,, , >
j(3oo. added, as the case may
require, in order to have
the proper metal constituents. The ore, after being
mixed with the proper proportion of coal and antiflux-
ing material {crushed silicious rock or mine screen-
ings), is charged into furnaces which have pre\iously
been bedded with a sufficient amount of coal to start
combustion. The furnaces are then sealed, allowng the
temperature to rise to about 2300° F., at which point
it is held until the zinc and lead pass off together in the
form of fume, which is conducted by means of suction
fans through pipe-lines for a distance of about 500 feet,
where it enters large brick bag houses. The fumes
have by this time lost considerable of the heat, so that
WHITE PIGMENTS 41
they may be gathered into fabric bags, where the gases
pass out and the pigment is collected. From the bag
house the pigment is conveyed to an automatic packer
and placed in barrels of suitable weight, and is then
ready for the consumer.
An actual chemical analysis of an average type cf
Ozark White shows the following:
ZnO 59-32 per cent
PbS04 39.05 " "
ZnS04 0.78 " "
SO2 0.05 " "
H2O... 0.66 " ''
AS2Q8 0.12 " ''
Total 99.98 per cent
Zinc Oxid
Formula, ZnO; Specific Gravity, 5.2
Zinc oxid as a paint pigment is only sixty years old,
and when it is taken into consideration that in that short
space of time its use has grown until in 1905 nearly
seventy thousand tons were used in the paint industry
in the United States, it speaks for itself that the material
must be of exceptional merit to have advanced so rapidly.
At the same time, although it is impossible to obtain
any exact figures on the subject, it is probable that
more than one half of these seventy thousand tons was
used in connection with other materials.
The discovery of zinc oxid by Le Clair in France and
Samuel T. Jones in America is sufficiently well knownti,
and has been quite thoroughly written up in other books.
The former made zinc oxid by subliming the metal; the
latter made it by subliming Zincite and Franklinite ores.
The specific gravity of zinc oxid wall average 5.2, and
fifty pounds will take fifty pounds of linseed oil; in other
42 CHEMISTRY AND TECHNOLOGY OF PAINTS
words, to produce the proper mixed paint it will require
a far greater proportion of linseed oil than white lead will
take. It is generally stated in text-books that zinc
oxid is not affected by sulphur gases and therefore
will not turn color. This statement is not exactly
correct; the author always contended that zinc oxid is
not visibly affected by sulphur gases, but there is no
doubt, as any chemist will admit, that zinc oxid is
affected by sulphur gases, although not to the same
extent as white lead. As zinc sulphide, zinc sulphite,
and zinc sulphate are white products, the absorption is
not evident to the eye, and hence the erroneous state-
ment has cjept into use that zinc oxid is not affected
by sulphur gases.
When mixed with linseed oil and the proper amount
of drier, it sets and dries much more slowly than white
lead. Nevertheless this drying continues in the form of
progressive oxidation until the surface becomes very hard.
A comparison between zinc-oxid and white-lead paints
will show that the progressive oxidation which takes
place when white lead dries produces a chalky mixture,
while the reverse is true of zinc oxid, which will produce
a hard and brittle vitreous surface which is somewhat
affected by temperature changes. Owing, therefore, to
the diverse effects of the two pigments, a combination
of lead and zinc is often well recommended. The hard
drying zinc has not, however, been very well understood.
Fifteen years ago the author undertook a series of exp)eri-
ments and found that the drier was very largely respon-
sible for the hardening action of zinc. If the linseed
oil be prepared with litharge (PbO), the resulting zinc
paint will last far longer and be much more flexible and
consequently not readily cracked when exposed to a
variation of temperature of even 130° F., such as we have
f-
WHITE PIGMENTS 43
in this climate. If, however, a drier is used in which
manganese (MnOi) and red lead (PbiO«) have been cooked
with the oil, the action of the manganese continues until
a \itreous surface is the result. It is owing to the result
of these investigations that the use of American zinc
oxid'made from Franklinite ore has become so general
for the manufacture of white table oilcloths. (See
Journal of Society of Chemical Industry, No. 2, Vol.
XXI, Jan. 31, 1902.)
UTien enamel paints
are made of an oil var-
nish and zinc oxid, and
the drier in the varnish
is composed of manga-
nese and lead, the enamels
eventually become hard,
exidently through the cata-
lytic action of the man-
ganese. It is desirable to
omit the manganese ^ in
high grade enamels, or,
where manganese must be
used in order to obtain
a rapid setting, the borate of manganese should be
employed, but only in very small quantities.
The American zincs are:
First. The Florence Red and Green Seal zincs, which
are made by the sublimation of the metal and are prac-
tically pure and equal in all respects to those made in
France and Belgium.
Second. The New Jersey zinc oxids, which are made
from Franklinite ore and are free from lead and fre-
quently run over 99 per cent ZnO.
Third. Mineral Point zinc, which is made at Mineral
No. 7. Americ.v-v Zi.vc Oxid — Photo-
micrograph xjoo, very pure and very
uniform in gi^in; this oxid is made
direct from the ore.
44
CHEMISTRY AND TECHNOLOGY OF PAINTS
Point, Wisconsin, and contains from 2 to 4 per cent of
lead sulphate.
Fourth. The leaded zincs made in Missouri, which
contain from 4 to 10 per cent of sulphate of lead.
Zinc oxid chalks to some extent in the same manner
as white lead, but only if the atmosphere is charged with
carbon dioxid or salt. The same experiment which was
carried out with white
lead in order to show its
solubility in a solution of
carbon dioxid was carried
I out with zinc oxid and
1 the same result obtained.
I Much weight cannot be
given to these experi-
ments, because these chemi=.
cals are not always present
in the atmosphere. They
are merely chemical results
which demonstrate both
the cause and effect, but
it is of some interest to
know why the paint films perish. The zinc oxids made
from western ores are slightly more permanent than
those made from the New Jersey ores, and as paint
materials they possess the advantage of containing a
larger quantity of lead sulphate.
Nearly all zincs contain a small percentage of zinc
sulphate. Much unnecessary trouble has been caused
by the criticism against zinc sulphate. Where a paint
contains moisture or where water is added in a very
small amount to a heavy paint in order to prevent it
from settling, and not more than one per cent of actual
water is contained in the paint, zinc sulphate forms an
No. 8. French Gaeen Seal Oxid —
Photomicrograph xjoo, much whiter
than the American zinc made from the
metal, but coarser in grain.
WHITE PIGMENTS 45
excellent drier, particularly where it is desirable to make
shades which contain lampblack. The outcry against
zinc sulphate is unwarranted, because as much as 5 per
cent is used in making a patent drier. The amount of
zinc sulphate, however, in most of the dry zinc pigments
probably decreases with age. Zinc oxid or other zinc
paint which will assay i per cent of zinc sulphate will,
when kept in storage for six months, show a decrease in
the zinc sulphate to one half of i per cent.
In the enamel paints the presence of zinc sulphate is
not a detriment, and in floor paints it might be con-
sidered as a slight advantage, for it aids in the drying
and hardening. However, too much of the soluble salt
is never to be recommended.'
ZiNOX
This is a hydrated oxid of zinc not manufactured in
this country, but made and used almost entirely in
France. It is not yet sold dry, but generally sold either
in the form of a ready mixed enamel or in a semi-paste
form, and is presumed to possess advantages over zinc
oxid. From experiments which the author made it has
been found that the hiding power and working quality
are practically the same as that of zinc oxid. It pos-
sesses, therefore, no marked advantage over a zinc oxid
enamel, although it is stated that it remains in sus-
pension longer than any other pigment. The zinc oxid
enamels all remain in suspension a very long time, and
even though they settle they do not settle very hard and
can be very easily stirred. In thinner media, such as
are used for the manufacture of flat wall paints, the
hydroxid of zinc has some advantage over the oxid, as it
produces a paint that remains in suspension longer and
is more ready for use than that made from the oxid.
46 CHEMISTRY AND TECHNOLOGY OF PAINTS
LlTHOPONE
Synon\Tii : Oleum White, Beckton White, Charlton White, Pono-
lith, Jersey Lily White, Orr's WTiite
Chemical Formula, ZnS + BaS04; Specific Gravity, 4.2
When solutions of zinc sulphate and barium sulphide
are mixed together in molecular proportions a heavy
flocculent precipitate is formed according to the following
reaction : ZnS04 + Aq + BaS + Aq = ZnS + BaSO* + H2O.
The theoretical percentage mil be about 29^ per cent
zinc sulphide and 70^ per cent barium sulphate. This
precipitate as such has no body or covermg power, and
when washed and dried is totally unfit for paint pur-
poses; but John B. Orr, of England, in 1880 discovered
that when it is heated to dull redness, suddenly plimged
into water, ground in its pulp state, thoroughly washed
and dried, its characteristics are totally changed, and it
makes a very eiTcctive and durable pigment for paint
purposes. In the first place, it is then a brilliant white;
in the second place, it is extremely fine in texture; and
in the third place, it has more hiding power than pure
zinc oxid. Owing to its chemical composition it is
stable in every medium kno^\^l for paint purposes, except-
ing those which are highly acid. It took several years
to perfect the manufacture of lithopone, but it may be
easily said that at the present time lithopone is made
with great uniformity and has valuable properties, as
will hereinafter be shown.
The method of manufacture is quite simple, success
depending very largely on the purity of certain materials.
It is worthy of mention, however, that the average chem-
ist unfamiliar with both the theory and practice of its
manufacture cannot make it successfullv. In the first
place, solutions of barium sulphide and zinc sulphate of
WHITE PIGMENTS 47
known composition must be made. The fact that they
are impure has no effect on the ultimate product, provided
the chemist knows the impurities he has to deal with
and the simple methods for their elimmation. For
instance, the zinc sulphate must be free from iron or a
yellowish product is the result. The solutions must be
standardized for each batch. The impurities can be
eliminated during the process of manufacture, or, more
properly speaking, before they are pumped into the pre-
cipitation tub.
The barium sulphide, however, is quite pure, for the
reason that metals like copper, iron, and manganese
which are likely to be
present, form insoluble £
phides. Barium i
made by heating 1
(BaSO*) to dull redness .-^^
with coal, petroleum re- •^■. »^;^S''' ■^i^---rC^'H^^>^
siduum, pitch, sawdust, or ;y^^"^-i-^A-l:^^^\'4v^
other materials having a vE'^^iS^^S^'^^L'?^'^'?
high percentage of carbon. ^^^^Jj|^?;>i*i!*^^l^'
The resulting reaction may
be represented by the
following equation: BaSOi no. g. Lithopose (dry) — Phoiomi-
+ 4C = BaS + 4CO, al- crogiaph X2SO, exceedingly fine and
., , , . uniform in grain.
though under many cir-
cumstances the reaction is more slightly complicated.
After the reaction is completed and before the air can
have any influence on the sulphide, the mass is digested
in vats and filtered; when the solution reaches a density
of 17°, Baum€ long, yellowish, needle-shaped crj'stals
separate from the mother liquor. These crj'stals are
almost chemically pure barium sulphide.
With the proper concentration of the solutions, proper
48 CEEUISTRY AND TECBNOWGV OF PAINTS
temperature and speed at which the two solutions are
poured together, the resulting precipitate will be of such
ph>sical characteristics that it can be most easily filtered
and dried. It is then placed in muffles and heated above
920° Fahrenheit, suddenly plunged into water, again
ground, washed, and dried. It is then ready for the mar-
ket. The overheating of the precipitate decomposes some
of the zinc sidphide and converts it into zinc oxid. All
of the earlier manufacturers overheated their product, and
that is the reason why litho-
pone formerly contained
from 5 to 10 per cent zinc
oxid, whereas theoretically
1 it should have contained
none. The manufacturers
I of the present day, however,
have overcome all these dif-
ficulties, so that a remark-
ably uniform product is
obtained, the percentage of
No. 10. LiTHOPovK (ground in oil) — zinc oxid being small indeed.
[■ii.>i.mii.Togni|>h xijo, cMccdingiy \\rg jj^ve here an excel-
lent example, as has been
staled under another chapter, of a pigment containing 70
per cent barium sulphate, which may be regarded as
pLTfc'cUy pure and normal, and yet twenty-five years
agi) any ])ignu'nt containing far less barium sulphate
Ihaii lithopone would have been regarded as adulterated.
\ii man ran reasonably state that barium sulphate is an
adullcrant to lithopone, for the obvious reason that it is
a constilucnt jKirt of the pigment.
Lithopone has gone through many vicissitudes; no
pigment has been blackguarded quite as much as this,
and yet no pigment has survived its condemnation as
WHITE PIGMENTS 49
well as this. Almost every paint manufacturer in the
United States finds some excellent use for it. Within
the last seven or eight years lithopone has come into its
own, and today there is no paint manufacturer in the
United States, to the best of the author's knowledge,
who does not use this material. Ten years ago very
few paint manufacturers used it at all.
Since 1906 riiany chemists, including such capable
men as Professor Ostwald, have attempted to find the
cause of the darkening of lithopone in sunlight. WTien
night comes a change takes place, and the foUowdng
morning lithopone is as white as it ever was. This
proj>erty is called the "photogenic'' quality. This photo-
genic action goes on continually, and there have been
a large number of investigators who have attempted to
overcome this, and a review of the literature shows that
most of the methods, with two or three exceptions, have
been empirical. It has remained, however, for Professor
W. D. Bancroft of Cornell University to delegate one
of his students, W. J. O'Brien, to make these investiga-
tions, and the full account is recorded in Volume XIX
of the Journal of Physical Chemistry, 113-44 (1915);
an extract is herewith given of the phenomenon.
That the darkening in sunlight is due to the formation
of zinc from zinc sulphide was shownn by the fact that
the dark product reduced ferric alum, as showTi by the
api>earance of a blue color with potassium ferricyanide,
and that it is readily soluble in acetic acid, in alka-
lies, and in solutions of sodium chloride and sodium sul-
phate. The zinc is a direct product of the action of light on
zinc sulphide. The results of the investigation are sum-
marized as follows: Quenching in water prevents further
oxidation of the red-hot zinc sulphide. It also disinte-
grates the semi-fused mass and dissolves out most of the
50 CHEMISTRY AND TECHNOLOGY OP PAINTS
soluble salts. Heating the barium sulphate-zinc sulphide
precipitate is necessary to dehydrate the zinc sulphide
and to change its physical condition, so that it forms a
dense mass wdth good body which can be ground more
readily. The yellow color produced on overheating is
due to an oxid film, as was shown by Famau. The
darkening of lithopone is not due to impurities such as
iron, lead, cadmium, etc. The presence of salts which
form soluble zinc salts, such as sodium chloride, sodium
sulphate, etc., accelerates the darkening of the lithopone.
These salts dissolve away the zinc oxid film. This is simi-
lar to the behavior of magnesium in water. Magnesium
does not decompose water very readily at ordinary
temperatures. In the presence of magnesium chloride,
however, the action takes place vigorously. The pres-
ence of salts which form insoluble zinc salts, such as the
alkaline phosphates, bicarbonates, ferrocyanides, and bo-
rates, retards or prevents the darkening of lithopone. The
action of light on the zinc sulphide is a reducing one,
hydrogen sulphide and metallic zinc being formed. The
reaction is not a reversible one; the metallic zinc formed
is oxidized to zinc oxid; barium sulphate is not neces-
sary for the darkening of the zinp sulphide. Heating the
zinc sulphide is not necessary to get it to darken, al-
though heating makes the zinc sulphide more sensitive
to light, probably because the reducing atmosphere and
the sodium chloride used remove the zinc film more
readily. The zinc oxid film can be removed by boiling
in a concentrated solution of zinc chloride. The zinc
suli)hide so treated will darken in the presence of a
reducing agent. When barium sulphate is precipitated
with the zinc sulphide, it aids the darkening, due to the
fact that it adsorbs the zinc sulphide, thereby giving
increased surface exposure of the zinc sulphide. It
WHITE PIGMENTS $1
probably also 'adsorbs the metallic zinc. The zinc sul-
phide will darken without the presence of a reducing
agent if it is precipitated with barium sulphide and
boiled in a concentrated solution of zinc chloride. The
barium sulphate probably adsorbs metallic zinc as well
as zinc sulphide, thus making the latter sensitive to
light. The patented processes for the prevention of the
darkening of lithopone depend upon the formation of an
insoluble film around the zinc sulphide. It is impossible
to make a lithopone that will not darken unless there is a
film protection of some kind over the zinc sulphide. A
lithopone of good quality that would not darken was
made by producing an oxid film on the zinc sulphide and
keeping the oxid content above 3 per cent and below 5
per cent. Aluminium oxid can be substituted for the
zinc oxid. A film of sulphur protects to some extent;
no experiments were made to determine the maximum
efficiency possible.
From the above we can readily see that the theor>' is
a tenable one, and that the action of light on zinc sul-
phide is a reducing one, sulphuretted hydrogen and
metallic zinc being formed. Metallic zinc is again con-
verted into zinc oxid, and the color of the metallic zinc
mixed with the other bases gives the gray shade that is
apparent. The manufacture of a lithopone, therefore,
that would not darken, by producing an oxid film and
keeping the oxid content above 3 and below 5 per
cent, would have its disadvantages, for in a rosin var-
nish or an acid resin varnish livering would eventually
take place, and one of the principal features of lithopone
has been that an acid resin or rosin varnish could be
used and no chemical reaction would take place.
The large use of lithopone today is for flat wall paints,
for it can be mixed with the China wood oil-rosin var-
52 CHEMISTRY AND TECHNOLOGY OF PAINTS
nishes without the danger of livering or hardening, and
it has every advantage as far as hiding power and freedom
from mechanical defects that white lead and zinc oxid
have, with the added advantage of being non-poisonous
(although the danger of using a poisonous material on a
wall is largely overestimated). Lithopone is likewise
very largely used in the cheaper grades of enamel paints.
As an interior white, a first coat white, or as a pigment
in the lighter shades for floor paints, lithopone cannot be
excelled for its body, durability, hardness, fineness of
grain, and ease of application. It does not oxidize
progressively, and this single feature has made it inval-
uable to the table oilcloth and floor oilcloth industry
throughout the world. Its indiscriminate use, however,
is not to be recommended, and the paint chemist should
be permitted to decide when its value is the greatest.
As a marine interior paint, either as a first coat or for
making neutral paints where other whites would be nec-
essary, it is found to outlast both zinc oxid and lead
carbonate.
CHAPTER III
The Oxids of Lead
«
The oxids of lead used in making mixed paints are
principally litharge, which is PbO, and red lead or orange
mineral, Pb304.
Litharge
Chemical Formula, PbO; Specific Gravity, 9.2 to 9.5
Litharge is the first oxid of lead; that is to say, when
lead is melted and heated in a current of air the first oxid
produced is the PbO, yellow in color, and known as
litharge. Verj"^ pure litharge has the color of pale ochre.
Litharge in the manufacture of preservative paints
has excellent protective qualities, because it is basic and
resists corrosion. Furthermore, litharge and linseed oil
make a very hard cementitious film which withstands
abrasion, but unfortunately litharge combines wdth lin-
seed oil so rapidly that when used in mixed paints to
any great extent it tends to "liver'' and saponify. On
the other hand, a number of black paints which are
composed of lampblack, carbon black, charcoal, or a mix-
ture of these, are held together by the use of litharge, and
where these paints are used within a month or two after
they are made they serve their purpose perfectly.
Litharge is soluble in acetic acid, and the other
impurities in it are generally insoluble, so that a very
rapid test can be made from the paint manufacturer's
point of view by simply boiling in acetic acid. Litharge
varies in texture under the microscope, as is shown in
the accompanying photomicrographs.
53
•*
\
54 CHEMISTRY AND TBCHSOLOGY OF PAINTS
Flake litharge is generally used by varnish makers or
oil boilers for making drying oil, but the more finely
powdered forms of litharge have a peculiar construction,
and when the litharge is impure and contains metallic
lead and red lead it is distinctly noticeable under the
microscope.
Red Lead
Chemical Formula, PbjOi; Specific Gravity, q.o
Red lead is a very heavy orange-red pigment, more or
less crystalline in structure. It is prej)ared by heating
litharge lo a temperature of 600° to 700° F.
^. ^^,. ^ Owing to the conditions
^:'y'-^^''''^^.''^- ,. under which it is made it
'v ;' * V-' , contains from a trace to
'^^ ■ ,'., ' *\^ an appreciable percentage
' ' ■ *^kk '^^ litharge (PbO), and
_■-'•'' '"^h when used for pdnt pur-
,r ; . -...^^.t^ poses it cannot be said
■ '" .' Vi' ^^^^ ^ small content of
■ ^ _ , ,,' - t ■ :, -'J' litharge does any harm.
'V^''*--y.»V*''^'*&'V':' When prepared in linseed
"^■**SvV^*' ' °^' '' '""^'^ ^^ freshly used,
otherwise it forms a dis-
Nm. I ] . !.iTiiAKi;i. - I'liiitomicniirraiih xioo. . ... - i i.
tinct combmation with hn-
scf'l oil and bt'comos hard and unfit for use. In its
pli\si(al charaiifristicrt it can be compared Mith plaster
nf pjuis. Il ails \cry much like jjlaster of paris when
m'wvA with walcr. Once set, il may be reground and will
iic\»T j^el anii'ii- T^ use as a priming coat for structural
sitcl li;is been ennrmous, but engineers who have studied
llu' subjcrl liavc fume to the conclusion that there are
olliiT nuilcrials just as good, or better, which are easier
to upply and <tn not possess the characteristic difficulties
TEE OXIDS OF LEAD 55
of application. The author has made many investigations
on this subject, and for further detail would refer the reader
to the Journal of the Society of Chemical Industry,
Vol. XXI, January, 1902, and Vol. XXIV, May, 1905.
There are some manufacturers in the United States
who make red lead from litharge and use nitrite of soda
as an oxidizing material, and in the manufacture of this
tj-pe of red lead carelessness in manufacture will result
in a fairly large percentage of caustic soda remaining in
the red lead. Caustic soda finds its way frequently into
Utharge when it is made
by what is known as the c ' t.j^J^'i
nitrate process, in which
nitrate of soda and me
tallic lead are fused to '*alI^*Vi?J^^'5?i
gether, jielding an oxid of *^^,J^^^''
lead, PbO, and nitrite of ^^ tf^ "^^ -j
soda, NaNOj.' Red lead '5i'.Jlv
manufactured by this pro- ^Ipj
cess will usually contain a
small amount of caustic ^^w*,/
soda and nitrite of soda .^ , ''^*~
No 13 Litharge — Photom crograph X300
and such red lead, al
though otherwise pure, makes a very poor paint, because
the caustic soda saponifies the linseed oil, and exposure
to weather of a few months will turn the red lead white
or pinkish white and make it very soluble in rain water.
Rust is also rapidly produced under such red lead, and
therefore in specifying red lead it is well for the engi-
neer to insert a clause that an aqueous mixture of red
lead shall show no reaction with phenolphthalein.
Within the last five years a great improvement has
been made in the manufacture of red lead, and this
' See Holly's "Analyas of Paint and Varnish," p. 221.
56 CHEMISTRY AND TECHNOLOGY OF PAINTS
improved form has been known as Dutch Boy Red Lead,
which is practically a chemically pure Pb804. Pure red
lead was the one material which had never been sold either
ground in oil or ready for use, owing to the fact that the
large content of litharge combined with the fatty acid
of the oil and the glycerine and formed a lead soap. It'
is well known that litharge cement, used for many pur-
poses around a factory, is litharge and glycerine, which
sets up hard wdthin an hour and forms a vitreous product.
It is also well known that when linseed oil is neutralized
with caustic soda, and the resulting linoleate of soda
soap filtered out, a ready mixed or semi-paste red lead
can l:)c made which will remain soft for many months,
l)Ul the proprietary' brand of red lead just referred to
nitinufactured by the National Lead Company, is a pure
red lead similar in composition to orange mineral, which
remains soft and produces a paint that has many advan-
tages over the old-fashioned red lead.
Many engineers and shipbuilders prefer to use dry
red lead, and a proper specification for dry red lead
should be one that will contain the minimum amount
of litharge.
It cannot be denied that red lead is one of the best
priniing materials that we have, but under no circum-
'.L'liKcs sliould less than 28 lbs. of dry red lead be mixed
vvilh one ^mIIoh of linseed oil. Many of the bad efifects
;mr| faihires of red lead are not due to the lead itself,
hill lo 1)11(1 a])i)licati()n and insufficient dry materials.
A. ;i mailer of fad, the best results with red lead are
oLi.iinrrI (iu tlie author's experience) by using 33 lbs.
.11 'I our ;«;allon of linseed oil. To this oil may be added
ni,i hall |)inl of any good Japan drier.
A . a iifiniin^ coat red lead possesses excellent pre-
.1 i ;iiiv<' ^jualilies, providing it be properly applied wdthin
THE OX IDS OF LEAD
57
a reasonable time. If red lead be used in the proportion
of 17 lbs. to one gallon of linseed oil it forms a ver>' poor
coating on account of the separation of the pigment
from the oil, particularly on a vertical surface. In a
pamphlet published by a manufacturer a large number of
precautions were given to the consumer for the prepara-
tion of red lead as a priming coat, the neglect of any
one of which might produce failure for the paint. As a
prominent engineer remarked, he did not care to specify
a paint in which there
were seventeen chances
of its failure due to a
possible faUibility of hu-
man nature. The use of
a drj' pigment mixed with
oil and applied within one
hour of its mixture is con-
trary to the progress of
the present day, when
paints finely ground by
machinery are taking the
place of all others. A dry
pigment stirred by hand
in a pail of oU carries with it a large number of air
bubbles which become encysted and carry oxj-gen
and other gases to the surface to be protected. The
engineer should, therefore, not specify that a paint be
made entirely of red lead and linseed oil and sent ready
for use to the place of application when such specifica-
tions cannot be reasonably executed. On the other
hand, where red lead is specified the engineer or paint
manufacturer who can supply a material containing
between 40 and 50 per cent red lead and 50 and 60
per cent inert base is deUvering a far better article,
No. 13. French Oraxce Mi.vehal
Photomicrograph xijo, not vcr>' »
form in grain.
5$ CHEMISTRY AND TECHNOLOGY OP PAINTS
which can be more easily applied than the undiluted red-
lead alone.
The author made a large number of experiments on
red lead mixed with linseed oil containing a small per-
centage of drier, applying these mixtures to steel. The
mixture was first appUed the moment it was thinned, and
then at short intervals, up to the moment the red lead
began to combine with linseed oil so as to make it
impossible to handle the brush. The results of the experi-
ment showed that freshly
applied red lead was not
as good as it was if applied
one hour after it was mixed.
The paint with which these
experiments were made con-
tained 24 lbs. red lead to
one gallon of paint, which is
approximately equal to 33
lbs. dry red lead to one
gallon of oil. The difficulty
No. 14. Red l>u> - Ph.>.™i<ro«r.ph >" handling pamt of this
xjoo of paint iiim frcsUy applied, kind Is vcry gieat, owing
sliowing separation of . the pigment j^ jhg gxcessivc Weight of
from the oil. , . . , , ,
the pamt as earned by the
brush. Structural iron painters aU complain that muscular
fatigue ensues where undiluted red lead is used, and when
the inspector is not watching they will surreptitiously
add an excessive quantity of oil, or volatile thinner,
in order to lighten their labor, and for this reason red
lead has frequently failed, when as a matter of fact it
would have proved a perfect success had the original
siK'cifications been adhered to. On the other hand, there
should be no need of using a protective paint involving
such great difficulties when there are dozens of others
THE OX IDS OF LEAD 59
that are as good, not only from the standpoint of pro-
tective influence but also on account of the ease of
mechanical application.
It has been mentioned by many writers that one of the
serious defects of red lead is the ease with which it is
attacked by sulphur gases, but this objection does not
hold good where it is properly and quickly coated over
with a protective coat of the bituminous class. That
red lead in its pure or concentrated state is not as good
as a paint containing a solid
diluent has been shown time
and again where silica,
lampblack, graphite, silicate
of alumina, and such lighter
pigments were mixed with
it. Its extraordinarily high
specific gravity is very much
against its use as a paint,
but if a mixture of one
pound red lead and one
pound wood black is taken ,, -c , ...
' No. 15, Ked Lead — I iiotomicrograph
the average specific gravity xiso, applied one hour after miMng,
of the two is equal to that ^''"*"*"e separation and air bcUa en-
, . . 1 T 1. cysted in film.
of zmc oxid. Its spreadmg
and lasting power is increased, so that a mixture of
this Idnd is equal to a mixture of any of the good pre-
pared paints for structural steel. Two large exposure
tests made by the author in 1899 and examined in 1905
showed that a mixture of 50 per cent red lead and
50 per cent graphite ground fine and mixed in a pure
linseed oil containing 5 per cent of lead drier wore almost
as well as a mixture of 75 per cent Fe^Oj (ferric oxid),
20 p>er cent silica, and 5 per cent calcium carbonate.
The former paint, when the hand was rubbed over it,
6o CHEMISTRY AND. TECHNOLOGY OF PAINTS
showed slightly more destruction of the oil, the graphite
giving a stove polish eflfect on the hand. The latter
paint also showed a very slight stain on the hand, but not
quite as marked as the former. The metal underneath
both was in a good state of preservation, three coats of
paint having been applied. The exposure was made
on a slanting roof in New York City.
Red lead has had the great advantage of having been
the first protective paint ever used, for years no better
paint being known. In this respect it is analogous to
white lead. Much of the good reputation of white lead
is due to the fact that for centuries there was no other
white paint, consequently no comparison could be made.
It must be borne in mind that all these experimental
researches concerning red lead are based on very fine red
lead, and no consideration is given to the detrimental
reports concerning red lead due to the fact that it was
improperly made and coarse.
A laboratory test of red lead always shows up remark-
ably well. A steel saucer painted with red lead in the
laboratory will demonstrate that this pigment is superior
to many others, but a field test of material made accord-
ing to a laboratory" formula and applied on several tons
of steel will generally show the opposite, for the obvious
reason that in the laboratory a small test is usually
carefully applied and little exertion is necessary, either
with the mixing of material or for its application. The
temperature conditions of the laboratory being normal,
the person who mixes the paint usually scrutinizes the
result carefully. On the other hand, in the field or at
the shop a brush is used which will do the greatest
amount of covering \\ith the least amount of exertion.
The mixture may not be made by the best possible for-
mula, and, if it is, more thinning material is generally
THE OX IDS OF LEAD 6 1
added until it works freely. The vertical part of the
surface ^\dll, on account of its position, be more difficult
to cover, and the paint will sag or run from it; whereas,
the flat plate or saucer-shaped cup used in the laboratory
holds the material in place by virtue of its position.
Blue Lead
In the sublimation of Galena a peculiar sulphide of
lead is produced, which has been known commercially
as blue lead, on account of its blue-gray appearance.
This product has been on the market for several years.
The contention is that sulphur fumes do not affect it as
they affect red lead. As a priming coat it has been well
spoken of. Its composition is as follows:
Carbon 2.25 1.73
Lead Sulphate 52.92 49-79
Lead Sulphite 36 1.44
Lead Sulphide 4.55 4.93
Lead Oxid 37-48 4i-34
Zinc Oxid 2.45 i.oo
100.01 ICX).23
No truly representative analysis of this material can
be given, owing to the variation in the amount of sul-
phate, sulphite, and sulphide. The material is not very
fine; in fact, it contains an appreciable amount of grit,
which, however, is removed in the second grinding.
The pigment is not permanent to light, but in all
probability this change in its tone is due to a chemical
rather than to a physical decomposition.
CHAPTER IV
The Red Pigments
The red pigments used in the manufacture of mixed
paints are principally the oxids of iron, the red oxids
of lead, and the permanent vermilions. No space will
be devoted to the sulphide of mercury (quicksilver ver-
milions), as the use of these materials has been super-
seded entirely by aniline or para-nitraniline vermilion.
Likewise no attention will be paid to the sulphide of an-
timony reds, as they are obsolete in paint manufacturing.
iVmong all the red pigments in the paint industry
the oxids of iron take the lead as by far the most useful.
Several years ago the author called attention to the fact
that various forms of ferric oxid having the formula
Fe203 could be used as rubber pigments. The sulphur
used in the vulcanizing of rubber had no eflfect on the
ferric oxid, no sulphide of iron being formed in the com-
bination. On investigation it was found that some forms
of ferric oxid are remarkably stable in composition, acting
in many regards like a spinel. Exhaustive tests made
with some of the ferric oxids used as paints for the pro-
tection of steel and iron show that they are far superior
to red lead and to graphite as paint protectives, being
midway between the two in specific gravity. A mixture
of graphite and ferric oxid (containing 75 per cent Fe208
and 25 per cent silica) outlasted graphite by two years
and red lead by three years. These tests were made on
horizontal roofs, and eliminating the question of the cost
62
THE RED PIGMENTS 63
of the paints, the ferric oxid stood the test and was the
cheapest in the end. No argument can be adduced that
ferric oxid is a carrier of oxygen, for it is a complete
chemical compound, is not readily acted upon by dilute
acids, not affected by alkalis nor by sulphur gases, and
as a paint the author has not been able to demonstrate
that it reacts on linseed oil.
All of these arguments refer, of course, to a ferric
oxid of known purity and definite composition either as
pure Fe203 or as Fe203 containing 25 per cent of silica.
In the course of its manufacture from the waste products
of wire mills, for instance, or direct from ferrous sulphate,
the processes being analogous, there is a likelihood that
a small percentage of free sulphuric acid may cling
mechanically to the substance. A good sample boiled
with water and tested wdth methyl orange wall demon-
strate this defect. It is wise, therefore, under all cir-
cumstances to add up to 5 per cent calcium carbonate
in any or all of these ferric oxid paints. There is, how-
ever, another ferric oxid made from Persian ore. Over
one hundred analyses of this ore in the laboratory of the
author have shown that its composition will not vary
more than 2 per cent either way, it being 75 per cent
FciOi and 25 per cent Si02.
Venetian Reds
Venetian reds have sometimes been described as burnt
ochres, but this definition of the Venetian reds is incor-
rect. The generally accepted composition of the Venetian
red is a combination of ferric oxid and calcium sulphate,
in which the ferric oxid wiU run from 20 to 40 per cent,
and the caldimi sulphate from 60 to 80 per cent. When
ferrous sulphate is heated with lime an interchange or
64 CHEMISTRY AND TECHNOLOGY OF PAINTS
reaction takes place, the sulphuric acid of the copperas
going to the lime while an oxidation of the iron takes
place. Another method known as the wet method is
the direct reaction between ferrous sulphate and wet
slacked lime.
\^enetian red has been known as a paint pigment for
upwards of a centur>', and while theory would indicate
that it is by no means as desirable a pigment to use as
other mixtures of ferric oxid, it must be apparent that
-— j*^.^^^^ in view of the fact that it
^^•; ^m^ • ^^\ ^^^ given general satisfac-
s* ^^H^S^^^ A. ^^^^ ^' ^^ ^^ ^^ means as
/ . ^^ ' j%- - f ^P^ undesirable a pigment as
' ■ i/h ■• •■-"* K' \ chemists indicate. Theten-
-^ ' ^;- » ;' ^ 'I dency, however, at the
%* -> ^ ** • ^ ^f present time is for manu-
^ , > / facturers to buy strong
pure oxids and reduce
them with other inert
fillers, for the principal
No. i6. En(;lisii \'i:netian- Red — reason that a Venetian red
Photomicrograph X250, showing cai- carrying a high percentage
cium suli)hate crystals. r 1 • 1 i_ x j
of calcmm sulphate and an
unknown quantity of water or moisture tends to become
hard in the package, whereas the mixtures of known
composition remain soft for many years. Venetian reds
arc all of the familiar brick color shade, the color of
bricks being caused by the same pigment as the one that
gives the color to Venetian red.
Indian Red
This is supposed to have been named by Benjamin
West, a celebrated American artist who lived more than
a century ago, and who as a boy used a few primary
THE RED PIGMENTS 65
earth colors as pigments for paint. One of these was a
natural hematite, and he observed that the Indians used
this for painting their faces. The name is also supposed
to have had its origin in the fact that "Persian Gulf
Ore," which was found in the Orient, was exported to
England under the name of "East Indian Red." This
Persian Gulf Ore is likewise a hematite, and later on a
similar ore was found in parts of England which, when
mined, looked very much like coal, but when crushed and
ground in water turned
a deep blood-red. The
old name for this mineral
is still "blood-stone," and
some very fine specimens
of this mineral are still
mined in England in con-
junction with beautiful
quartz crystals, so that
we find in England a care-
ful selection.
The native Indian red no. 17. auemcw Venetian red-
Will run 90 per cent FCjOj, Photomicrograi)h x»5o. showing fine
, , grains of calcium sulphate.
the American 88 per cent,
and the Persian 75 per cent, the balance in every case
being silica. The Indian red of commerce, however, is
an artificial product made like the base of the Venetian
red by calcining copperas and selecting the product as
to shade. There is no pigment, with possibly the excep-
tion of lithopone and artificial barium sulphate, which will
approach Indian red in fineness of grain. The prices
which a fine, pure Indian red or ferric oxid of any shade
will command are most remarkable, many tons being sold
e\-ery year in large quantities at as high a price as fifty
cents per pound and used entirely for polishing gold,
66 CHEMISTRY AXD TECllXOLOCY OF P.ilXTS
sil\er, and other metals. The well-known "watch-case
rouge" is nothing but pure Indian red which has been
ground, washed, and treated mechanically with so much
care that three-cjuarters of its selling price is repre-
i| . ^ sented in the labor of manip-
V^-fc, ■ -^ \' : - ulation. If, therefore, fine
/ > ." " . ♦»/ »*' *V ferric oxid be mixed with
i^V '~,.j'*'\. ' .*V'-' linseed oil it can be easily
■ ' U ^■'".i-'^'t'f:- ' ^*^" iiom the nature of the
''^' ..,' , m'"--* .• *^^'' physical characteristics of
* •^,^*'v;, ^-^ "^ 1 the pigment that a remark-
. ji'- .^ ■■_.*'• ably good result is obtained.
< ■', . ,'f Permanent Vermilion
■^■".'ji'"- It may be of interest
\... iX. A-ji.cii \\ iii.vATiTi; — i'ii..[<.- to the chemist unacquainted
tiij. j.-t-m-li yiv. ^-iKoviNj! ;i fciv large- ^^-jth the manufacture of
'■''""' dry colors to know that
rji^lish vfrmilinn (sulphide of mercur>'), of which the proto-
l\|)cs Jirc ChinL'sc vcrmil-
\iiiiTiiiin quicksilver /^ % V*-'^^***^
■riiiMiun, etc., was for-
M'd whcrev
f-%.;'.-*^A
irii-rlv iiM'd wherever a iicr- /"S.^* • i* * '^■■^ N^
iiuiji.-jil n-d was desired; /'-l^^Va- '^''/.^.^ ::^ '-'A
;iij«l piirticularly for mil- jL** "/i'.,.^ j -'41. ,'t''r^ ^*i
..,;,<l vv..rk was this ver- ^A''V■rf,>'*^i^ '*"''"■ >\,
i.iilir.n 111.- niily n-<l that ■,;'>'• -V"* '"' /*)^^.^*->
if mLTCury is a forced
■, whidi has the com-
THE RED PIGMENTS 67
position just described, is also red, but not very
bright, and that found and made in Austria, known
as Trieste vermilion, has always been regarded as the
most permanent of these sulphide of mercury reds.
Mixed paint manufacturers do not use it, and in fact
paint manufacturers generally have discarded it, for the
reason that the so-called para-nitraniline reds are better,
cheaper, and more permanent.
In order that the chemist may understand the com-
position of the para-vermilions, a complete formula is
given for their manufacture.
Reactions involved in Making Para-red
Part I, (Solution of Para-nitraniline and Diazolizing.)
NO2 NO2
C6H4 +2HCI = C6H4 .2HCI
NH2 NHo
(para-nitraniline) (para-nitraniline hydrochloride)
NO2 NO2
CeH4 .2HCI -h NaNOa = C6H4 -h NaCl -h 2H0O
NH2 N : NCI
(benzene nitro-azochloride)
Part 2, (Beta-naphthol Solution.)
C10H7OH + NaOH = CioHTONa -h 2H2O
(beta-naphthol) (sodium beta-naphtholate)
Part J. (Mixing of No. i and No. 2 to Produce Color.)
NO2
C6H4 -h CioHyONa
N: NCI
(benzene nitro-azochloride) (sodium beta-naphtholate)
NO,
= C6H4 + NaCl
N: NCioHeOH
(Para Red)
68 chemistry and technology of paints
Para-nitraniline Lake
Naphthol Solution
15 grams beta-naphthol or beta-naphthol R.; 30 grams caustic
soda lye 22° Be.; 10-20 grams para-soap P. N. (In sufficient
boiling water to dissolve thoroughly).
Di/vzo Solution
14 grams para-nitraniline. dissolved in boiling water; 25 grams
hydrochloric acid 20° Be. ; 200 grams ice.
WTien the solution is cooled to 32° to 35° F., add very slowly,
while stirring constantly, 34 grams nitrite of soda solution (29 gms.
nitrite in 100 gms. cold water).
Allow to stand 15 to 20 minutes. Then add slowly 35 grams
acetate of soda previously dissolved in cold water.
To the naphthol solution add the base you intend to use. 250
grams of blanc fixe give good results. For bluer shades use beta-
naphthol R. For yellower shades use beta-naphthol.
WTien these colors have been precipitated on an
orange mineral base they have been known to catch fire
spontaneously in the drying room, and therefore great
care should be exercised in their manipulation vrfth lead
bases.
There appears to be a difference of opinion among
consumers as to whether these reds are really permanent
or not. Careful investigation reveals the following:
The i)ara-vermilions are soluble in linseed oil, and there-
fore even when a pigment contains only 5 per cent
tinctorial matter it is useful and effective as a red paint.
White lead in any form mixed with a para-red destroys
its color and turns it brown. A few years ago when this
color first appeared on the market it frequently hap-
pened that it turned i)erfectly white when exposed to the
air, but when it was rubbed with raw linseed oil it turned
a brilliant red again, and a microscopic examination
THE RED PIGMENTS 69
showed that the fihn had been entirely incrusted with
very fine crystals of sodium nitrite and other salts that
had not been completely washed out of the lake pigment,
and so para-red obtained a bad reputation, not due to
the color, but due to the ignorance of the manufacturer.
Para-red has penetrative powers in both directions;
when painted, for instance, on a sheet of cloth for sign
work it will penetrate through and stain the under side
yellow. If white lead paint be lettered over it, it acts
the same and turns white lead yellow or a yellowish
brown.
Enormous quantities of this vermilion are made every
year, and so strong is this color that average analyses
of the paint used for agricultural implement purposes
wdll show the pigment to be composed of 90 per cent
barytes, 5 per cent para-red, and 5 per cent zinc oxid or
zinc sulphide. Its presence in mixed paints is very easily
detected by boiling with varnish solvents and noting the
peculiar orange color of the filtrate.
Helio Fast Red
This is also known as Harrison Red, and is perhaps
one of the most permanent pigments that we have of
the vermilion type. It is made from nitro-paratoluidine,
and in tinctorial strength is practically ten times stronger
than a quicksilver vermilion. It dries, however, very
badly, and when a sufficient percentage of strong drier
such as a resinate of lead and manganese is added, the
color tends to darken slightly on exposure. This color
does not bleed, and it is apparently insoluble in drying
oil; nor does it turn a white pigment into a brown, as
is the case with the para-reds. When this pigment is
mixed or reduced with a large quantity of whiting,
barytes, or other white base, and exposed to the air it
70 CHEMISTRY AND TECHNOLOGY OF PAINTS
apparently fades, and on close examination this fading
is found to be washing out of the pigment itself and the
exposure of the base upon which it is made, so that the
conclusion we must arrive at as regards the permanency
of this remarkable color is that when used in sufficient
strength it is permanent, but when diluted, reduced, or
adulterated to too great an extent the base upon which
it is made overpowers or masks the permanent pigment
itself.
LiTHOL Red
This is 2 -naphthy lamine- 1 -sulphonic-acid-diazo-be ta
naphthol, and is sold to color manufacturers in paste
form as a semi-finished color.
In the manufacture of permanent vermilion the fol-
lowing is the method of procedure:
The paste color is mixed with the desired amount of
base (blanc fixe, clay, barytes, whiting, etc.) and water
until a thin, uniform suspension is obtained. Barium
chloride to the extent of io% of the paste color is then
added and the whole steamed for about \ hour until
the shade is fully developed. The color is then washed
once or twice, pressed, and dried.
Lithol red has the advantage over para-nitranilines
in that it does not bleed, and that it does not turn dark
upon exposure. It is very largely used in the manu-
facture of permanent railway signal reds, and when not
reduced or diluted with too much clay and barytes is
permanent, but when it contains an excess of the so-
called recnforcing pigments it washes out and fades.
CHAPTER V
The Brown Pigments
The principal brown pigments used in the manu-
facture of paint, excepting the aniline lakes, are the burnt
siennas, the burnt umbers, burnt ochres, Prince's Metallic
or Princess Mineral brown and Vandyke brown.
The burnt siennas, whether they are American or
Italian, are a translucent form of ferric oxid and clay.
In other words, when the hydrated oxid of iron and clay
mineral are burnt ferric oxid is the result, and the clay
remains unaltered, any water in combination, of course,
being driven off. If the resulting color is translucent
and is of the nature of a stain we call it a sienna, but if
the resulting color is opaque and of the nature of a paint
we call it an oxid.
The umbers are similar in composition to the siennas,
with the exception that they all contain manganese and
are of a much deeper brown and do not approach the red.
The Princess Mineral browTi or Prince's Metallic
oxids are calcined carbonates, silicates, and oxids only
found in America, and are very largely used, particularly
for the painting of wood.
Vandyke brown is a very deep brown, and is trans-
lucent when finely ground, containing more than 50 per
cent of organic matter.
American Burnt Sienna
This is a permanent reddish brown pigment made by
calcining raw sienna, raw sienna being a hydrated oxid
of iron containing clay. When burnt the percentage of
71
72 CHEillSTRV ASD TECBSOLOGV OF PALWTS
FcjOj, or ferric oxid, ranges from 25 to 60 per cent,
depending upon the original ore. There is one grade
found in the Penns\'I\-ania section which assays as high
as 80 per cent ferric oxid, and is know-n as double strength
sienna. This is richer and deeper than the Italian sienna,
and when reduced with ordinary- clay and ground in oil
makes a staining pigment equal to the Italian. From a
raw-material standpoint the Italian siennas when tinted
with 20 iwr cent of white show a bluish tint, whereas the
. , American siennas show a
bro^^Tiish or yellowish tint,
and only one who has had
a great deal of experience
in tinting out these siennas
can tell empirically the dif-
ference between an Amer-
ican and a burnt sienna.
The Italian and the Ameri-
can siennas normally con-
tain some calcium salts,
Amkhiian Hi-KKT Sienna— but occasionally Some ores
i'i..4iHiii.r..Ktui.h x2;o, csceUeni quai- ^jg found which are free
i>, mil .imi gruin. j^^^ j.^^ compounds. For
paint puriK)ses, however, these are no better than these
lliat lonlain lime, for many grinders add from 5 to 10
)Mr iiriit (»f whiting to umbers and siennas to prevent
llii-ni from running or disintegrating when used as stain-
Italian Bx-rnt Sienna
(liiliiin Imrnt sienna is made from raw sienna, the
(iiw sienna ttt-ing a hydrated oxid of iron containing clay,
III y-liiili I III' iron predominates, the burnt sienna being
<(| lilt' same composition minus combined water. The
THE BROWN PIGMENTS 73
hydrated oxid of iron is normally yellow, and when
this is burnt the ferric oxid which is produced is red-
dish or reddish brown.
Italian burnt sienna differs from most American
burnt siennas in that its ferric oxid content is generally
greater. The Italian burnt siennas average from 60
per cent FcjOs to as high as 75 per cent. The American
burnt sienna, known as double strength sienna, which is
equal in iron content to the Italian, differs totally in
shade, the American being of the order of an Havana
brown, the Italian being of a maroon type.
Siennas in mixed paints are largely used for their
tinting quality, the resulting shade being a yellowish
maroon or salmon color of extreme permanence. After
several years' exposure a mixture of white and burnt
sienna will darken slightly, but will never fade.
Under the microscope a finely ground sienna shows
little or no grain.
Burnt Umber
Burnt mnber is a very useful pigment, and is found
in the United States and also imported from Italy,
Cyprus, and Turkey-in-Europe. All umbers normally
contain over 5 per cent of manganese dioxid, while
some of them contain as high as 20^ per cent manganese.
The Turkey umbers are generally richer in manganese
than the American umbers.
A typical analysis of burnt Turkey umber would be
as follows:
Calcium Carbonate 7 %
Silica 34%
Manganese Dioxid 14 %
erf
/o
Ferric Oxid 42
Alumina 3 %
100%
74 CHEMISTRY AND TECHNOLOGY OF PAINTS
A typical analysis of an American burnt umber
would be:
Silica and Alumina (clay) 60 %
Ferric Oxid 25 %
Manganese Dioxid 8 %
Calcium Carbonate 5%
Carbon and Carbonaceous matter 2 %
100%
These types would indicate that an American umber
is^ not as strong and does not contain as much ferric oxid
and manganese dioxid as a Turkey umber.
BLTusrx Ochre
Burnt ochre is distinctively an American color, and
differs in physical quality from burnt sienna in so far as
the burnt ochre has hiding power and the sienna has trans-
lucent or staining power. Burnt ochre is more like a brown
paint, and burnt sienna like a mahogany stain. Burnt
ochre covers solidly; burnt sienna covers translucently.
Some of the American siennas which are not good
enough for staining purposes are burnt and find their
way to the market as structural steel paints and railroad
paints of the browTiish red order; as such they are remark-
ably good in their protective quality against corrosion.
No standard of composition can be given, as burnt
ochre varies very much in the percentage of iron, some
of the burnt ochres ranging as low as 30 per cent iron
oxid and others as high as 70 per cent, the balance in
both cases being clay.
Prince's Metallic or Princess Mineral Brown
This is one of the best known paints, and has had a
successful career for more than fifty years. It is a very
THE BROWN PIGMENTS
pleasing brown pigment, which has an enormous use all
over the United States for painting wooden freight cars
and tor painting tin roofs. Where it is apphed to a flat
surface like a tin roof it has been used for many years
in its dr}' state, and mixed with half raw and half boiled
linseed oil in the field. It is at times fairly fine, and
while it is an excellent preservative for steel it may be
regarded as a better preservative coating for wood, as
many of the wooden bams in the country in the States
have lasted ten years when coated with two coats of this
pigment. The analysis of the material varies very much.
Geologically, the ore is
a carbonate, and Hes be-
tween the upper sihirian
and lower devonian, h {••
a massive material of blui^ll
gray color when mined, ['
and resembles limestone, v
although it contains a very \
low percentage of lime.
' The process of mining is
bj- shaft-work. The ore
itself lies between two hard
rocks and rarely ever ex-.'"" "' ''-.','., ,'.*"" '""^
I ceeds three feet in width,
[ and as a consequence the mining is an expensive operation.
[The ore is hauled to the kilns, where it is roasted,
I Tv'hich drives off the carbon dioxid and converts it into
I a sesqui-oxid. The milling is the ordinarj' process used
y in grinding any of the iron oxids.
The material was originally manufactured by Robert
I Prince of New York, who became interested in a slate
[ quarrj' located in Carbon County, Pennsylvania, from
twhich locality the original material came.
. «■ '■^■■
;*'^
I
76 CHEMISTRY AND TECHNOLOGY OF PAINTS
A fair analysis of this material is as follows
Oxid of Iron (Fej O3) 48.68%
Silica 33.37%
Alumina 12.08 %
Lime 2.02 %
Magnesia 1.25 %
Loss on Ignition 2.34 %
Undetermined 0.26 %
c
100.00%
As the material is not alkaline, the lime and magnesia
are undoubtedly combined with the silica, so that the
material other than oxid of iron is silicate of alumina,
lime, and magnesia. Sometimes, the percentage of Fe203
will run below 40 and sometimes it will go as high as 50,
but this really makes no difference in the paint, and in
view of the fact that it is a natural product and may
from time to time contain a little gang rock some leeway
must be given as regards its composition.
Vandyke Brown
Vandyke brown is a native earth, and is identical
with cassel brown. It is popularly supposed that
Vandyke first used this pigment as a glazing color in
place of bitumen, and as it is composed of clay, iron oxid,
decomposed wood, and some bituminous products, it is
fairly translucent and adapts itself for glazing purposes.
Because of the bitumen which it contains, it dries very
badly and very slowly, and has a tendency to crack or
wrinkle if the under-coat is either too hard or too soft.
Concerning its permanence, there can be no doubt that
it darkens considerably on exposure, like all the bitumi-
nous compounds, and many painters use a permanent
glaze composed of a mixture of ochre and black tinted
THE BROWN PIGMENTS 77
with umber. Where the effect of age is to be simulated,
there is no objection to its use.^
This pigment is used in mixed paints, principally on
account of its deep shade and translucent appearance.
It contains upwards of 60 per cent of organic matter.
A t^-pical analysis would be as follows:
Organic Matter 65 <^,c
Ferric Oxid 3 ^e
Calcium Carbonate 5 ^'l
Potash and Ammonia Salts 2
.■V
Moisture 25 ' c
* ** Materials for Permanent Painting" by Maximilian Toch.
CHAPTER VI
The Yellow Pigments
^ The yellow pigments are the ochres, the raw siennas,
chrome yellow, and the chromates.
The ochres are all rust-stained clay, and both, the
French and the American contain approximately 20 per
cent of rust or ferric hydroxid and the balance clay.
The raw siennas differ from the ochres in that the
amount of hydrated oxid of iron is often in excess of
that of clay, and the nature of the pigment is such that
when finely ground it is a stain and not a paint.
The chrome yellows are all lead chromate variously
precipitated and of varjdng composition, depending upon
the shade.
The other chromates, such as zinc chromate and
barium chromate, have come into use in paints within
the last ten years, owing to their alleged property of
preventing rusting.
American Yellow Ochre
There are large quantities of ochre found in the
United States, but principally in Pennsylvania and in
Cieorgia. There are, of course, a great many other
deposits, but for the paint industry these are the prin-
cipal sources. American ochre ranges in composition
from 10 to 30 per cent of ferric hydroxid, the balance in
either case being clay, and on this point it is well to note
that ochre and sienna have the same composition, except-
ing that there is generally a reversal in the percentages
^o
THE YELLOW PIGMENTS
79
of clay and oxid of iron. Some ochres found in America
are finer than those imported from France, although
French ochres as a general rule are decidedly more
brilliant in color.
■ In the trade there are many other ochres, which are
sold under the name of cream ochre, gray ochre, white
ochre, and golden ochre, all of which are clays containing
either carbonaceous matter
or iron rust, for, after all,
oqhre is simply clay stained
with rust.
Cream ochre contains
as low as 5 per cent of
iron rust or ferric hydroxid,
the balance being silica
and clay. It has very little
hiding power, and is con-
sidered of very little value
as a primer on wood, for
which it is used to quite
a large extent.
Gray ochre is silica,
clay, and carbonaceous coloring matter, or is colored
with a trace of ferrous hydroxid or greenish rust. It is
used as a filler, or for a cheap paint.
White ochre is nothing more or less than clay, and
has no value whatever as a paint material.
Golden ochre is either French ochre or American
ochre which is brightened ^vith some chrome yellow.
There are various shades of golden ochre sold, depending
upon the shade of chrome yellow with which it is mixed.
Some of them are perfectly orange colored, and contain
as high as 12 to 15 per cent of chemically pure orange
.ehrome yellow.
O. 12. OrDIN'ARV AUERlfAS" W ASHED
OcElRB — Photomitrograph X250, pow-
dered and Ixilted; lower in iron than
the French, but of uniform grain.
8o CHEMISTRY AND TECHNOLOGY OF FAINTS
Green ochre is similar in composition to gray ochre,
excepting that it contains a larger percentage of ferrous
hydroxid. It is principally found in Bohemia xmder
the name of terre verte. It has little or no hiding power
of itself, but is very largely used as a base for cheap
lakes on account of its
adsorbent quality for cer-
tain aniline colors.
Yellow oxid is a syn-
onym for raw sienna, and
is practically the same
thing. A typical analysis
of j'cllow oxid will show
hydrated oxid of iron 70
■ - -•^w^-krfVM^ P^"^ *^^^^ ^^ clay 30 per
■^WchtC^ cent.
No. jj. AuERicAs Waskkd (Xiire— For the benefit of the
PhotomicroRraph X250, of the same chemist it mUSt be Stated
comixisitiim as Trenrh <xhre. . , , ,
that when analyses are ■
not gi\'en and small percentages of lime and magnesia
are found, it is understood that these are natural con-
comitants of ochrey earths.
French Yellow Ochre
French yellow ochre has been used in America for
many years, and is analogous in composition to American
ochre; but as a general rule the French ochres are more
brilliant in shade. Nearly all of the French ochres which
are imported into the United States have a composition
of about 20 per cent of hydrated oxid of iron and So per
cent of clay, and one of the most popular brands has
for \cars been knowTi as J. F. L. S. These letters stand
for "Jaunc, Fence, Lave, Surfin," which mean, "Yellow,
Dark, Washed, Superfine." These letters are varied
TBE YELLOW PIGhfENTS 8i
according to the treatment that the ochre gets, but the
J. F. L. S. is the most popular.
In color, the French ochres are more brilliant, as has
been stated, but the American ochres are invariably
finer; but this, of course, refers only to the American
grades of equal price.
Chrome Yellow
Chrome yellow is a lead chromate of medium shade,
as precipitated from a solution of nitrate of lead and
potassium bichromate. The
lemon or lighter shades are
made from solutions acidi-
fied with organic or inor-
ganic acids. An organic
acid such as citric acid,
which forms a lead citrate,
changes the shade, pro-
•ducing a greenish lemon,
which may vary from a
greenish lemon to a bril-
liant canary, particularly No. 14. j. f. L. s. OcuttE — Photo-
if sulphuric be added. If micmgraph xjso. showing crystalline
an alkaline solution of po-
tassium bichromate be used an orange precipitate is
produced, so that a great variety of shades of this pigment
can be obtained.
All of the chrome yellows are perfectly permanent,
provided they are thoroughly washed to free them from
residual salts. Manufacturers are now abandoning the
old mechanical method of stirring chrome yellow after
it is precipitated, and are substituting air stirring, which
avoids any possible tendency to produce lead sulphide,
the air converting the sulphide into sulphite and sulphate.
82 CHEMISTRY AND TECHNOLOGY OF PAINTS
Chrome yellows when thoroughly washed are permanent
to light, but they cannot be recommended where sulphur
vapor is generated, owing to the formation of lead sul-
phide, traces of which detract from the brilliancy of the
color of the pigment.
The composition of chrome yellow is as follows:
Light Chrome Yellow
PbS04 -h PbCr04
or,
2PbC03 • Pb(0H)2-h PbCr04
or,
PbCr04 + Citrate
Tartrate ► of Lead
or Sulphate ^
Medium Chrome Yellow
PbCr04
Orange Chrome Yellow
PbO • PbCr04 = PbjCrOfi
Chromate of Zinc
Chromate of zinc has only come into general use
within the last ten years in mixed paints and paints
generally, on account of its alleged rust preventing prop-
erties when used as a priming paint on steel.
Chromate of zinc is made as follows: Zinc oxid is
boiled in a solution of potassium bichromate for several
hours and filtered and dried with sKght washing; or a
hot neutral solution of zinc sulphate is precipitated with
potassium chromate.
Chromate of zinc is soluble to a considerable extent
in water, and therefore should not be used as a finishing
coat, as rain will streak the surface. For example, a
green paint made of chromate of zinc and blue shows
yellow streaks when exposed to the weather.
THE YELLOW PIGMENTS S^
This material is used to some extent by artistic
painters, and as oil paintings are never subjected to the
elements it is under those circumstances a perfectly per-
manent color.
For interior painting and flat wall paints, chromate of
zinc, therefore, has an advantage, as much more brilliant
tones are obtained and much more delicate shades are
obtained than with the chromate of lead. It has very
little hiding power or opacity, and in tinctorial strength
is much weaker than the chromate of lead.
If contained in a mixed paint, when the pigment is
thoroughly washed with benzine and freed from oil or
medium, chromate of zinc can easily be recognized, be-
cause the pigment when shaken with hot water in a test
tube is invariably colored yellow. This, however, must
be further verified, as barium chromate reacts the same
way.
CHAPTER VII
The Blue Pigments
The blue pigments usually used in the paint industry
are artificial ultramarine blue, artificial cobalt blue, and
Prussian blue. The types of Prussian blue vary very
greatly \nth their manufacture, and are known imder
the names of Milori blue. Bronze blue, Chinese blue,
Antwerp blue, Paris blue, etc.
Ultramarine and cobalt blues are permanent to light
and alkali-proof. The Prussian blues are permanent to
light, but not alkali-proof.
Ultramareste Blue^
Ultramarine blue, whether it is artificial or genuine, is
chemically the same, with the one difference that the
genuine ultramarine blue is the powdered mineral known
as lapis lazuli, and ordinarily is the blue known under
that name. Furthermore, the mineral itself is foimd at
times in an impure state either admixed with slate or
gang rock, or contaminated slightly with other minerals,
and the genuine ultramarine blue may run, therefore,
from a very deep blue to a very pale ashen blue; in fact,
the lapis lazuli which lies adjacent to the gang rock is
ground up and sold under the name of ultramarine
ashes, which is nothing more nor less than a very weak
variety of genuine ultramarine blue.
PYom the standpoint of exposure to light or dr>dng
quality, the artificial ultramarine blue is just as good
1 ''Materials for Permanent Painting/' by Maximilian Toch.
84
THE BLUE PIGMENTS 85
as the genuine, and the only advantage that the genuine
has over the artificial is that the genuine is not so quickly
affected by acids as the artificial is.
It may be of interest to know that in 1814 Tessaert
observed the accidental fcj,'**ic'«*j
production in a soda oven
at St. Gobain (France) of /^^.^ ^i^^^'^
made by Huhlmann (at
St. Gobain in a sulphate
o\'en) and by Hermann
in the soda works at No. 25. Ultrvmahike Bmk — photo-
Schoenebeck (Prussia). microgm,.h xjoo.
In 1824 La Soci^t^ d 'Encouragement pour Industrie
offered a prize of 6000 francs for the production of artificial
ultramarine blue, which,
in 1828, was awarded to
J. B. Guinet, a pharmacist
of Toulouse, later of Lyons,
who asserted that he first
produced ultramarine in
1826. Vanquelin was one
of the three " trustees,"
holding the secret contrary
to the rule of the Soci^t^.
In -December, 1828,
Gmelin of Goettingen ex-
plained his process of mak-
ing artificial ultramarine
before the Acadamie des Sciences of Paris. He used as
No. 16. Ultkauarine Blue, ground in
oil, very uniform and fine — Photo-
micrograph XI 50.
86 CHEMISTRY AND TECHNOLOGY OF PAINTS
the basis a mixture of precipitated hydrate of alumina
and silex, which was later on superseded by China day
(kaolin).
In 1829 Koettig produced ultramarine at the Royal
Saxon porcelain factory at Meissen.
In 1834 Leverkus, at Wermelskirchen, and later at
Leverkusen, on the Rhine, produced the pigment.
In 1837 Leykauf & Zeltner, at Nueremberg, introduced
the manufacture of ultramarine into Germany.
Prices of ultramarine in 1830:
Natural $50.25 per pound
Artificial 4,05 per pound
Ultramarine is composed of alumina, silica, soda, and
sulphur, as follows:
Ultramarine (pure blue) containing a miTiiTniiTn of
silica seems to be a more or less well-defined chemical
body, i.e., a double silicate of sodium and alimunium
with sulphur as a poly-sulphide of sodium, or as a thio-
sulphate.
Ultramarines Poor Rich
in Silica in Silica
Alumina 29,00 23.70
Silica 38.50 40.80
Soda 22.50 19.30
Sulphur 8.20 13.60
Undecomposed 1.80 2.60
100.00 100.00
R. Hoffman gives the following proportions:
Alumina Silica
Poor in silica 100 128
Rich in silica 100 170
THE BLUE PIGMENTS 87
In resistance to alum the different products rank as
follows :
Lapis Lazuli First
Artif . Ultramarine (rich in silica) .... Second
Artif . Ultramarine (poor in silica) . . . Third
In 1859 Leykauf discovered the purple and red varie-
ties of ultramarine, which were produced by the action
of hydrochloric and nitric acids, and by heating ultra-
marine with calcium chloride, magnesium chloride, and
various other chemicals. In this way there were pro-
duced a variety of shades, and by the addition of such
substances as silver, selenium, and tellurium, even yellow,
brown, purple, and green shades were produced.
All of these colored ultramarines are exceedingly
permanent to light, but have little or no hiding power,
and when used alone are perfectly permanent.
The ultramarine blue which is made by means of a
potash salt instead of a soda salt has every analogy of
color and shade to genuine cobalt blue, excepting that
the genuine cobalt blue is not affected by acids as
rapidly as the artificial.
Artificial Cobalt Elite
The cobalt blue of commerce is the same as ultra-
marine blue, the difference being in the shade. Ultra-
marine, when mixed with thirty parts of a white pigment,
such as zinc oxid, produces a violet shade, whereas the
cobalt blues when mixed in the same proportion produce
a turquoise or sky-blue shade. Chemically, the com-
position of these ultramarines and cobalts will average
about 50 per cent silica, 22 per cent alumina, 15 per cent
sodium sulphide, in combination wath 3 per cent water
and 10 per cent sulphur. The addition of the slightest
88 CHEMISTRY AND TECHNOLOGY OP PAINTS
trace of acid to a paint containing ultramarine blue
liberates HiS, which always indicates the presence of
ultramarine in a blue or , bluish pigment. Under the
microscope ultramarine ,blue has a distinct crystal-
line appearance. When these crystals are badly de-
stroyed bj' fine grinding the color suffers very much, the
characteristic brilliant blue of ultramarine becoming an
exceedingly muddy shade. Its tinctorial power is very
weak, but it is exceptionally permanent to light, ii
.-■f'i..-. blue shades of mixed paints
■r^-iT- ^. J|j3^k ^^^ percentage of ultra-
^ -\^"|"f' *^-*^7^?^bik marine blue can be deter-
^^^'' t!^^- -^ ■i-Jc'^^M. mined either by difference
^■r-^' X--"''- •^- ?'«'^^^3P ^^ ^^ ^^^ percentage of
.•■C-».V"*^^^^''*i'\S2 sulphur present. If lo
^^ti'-'^^^^'.^.Ji^'j^jl per cent is accepted as
Vf^.'Ji ,. Y'L\'^<Ijm the amount of sulphur in
C'*'^V'" *■'"■((.'::. ./-^jJO^F ultramarine blue, a fairly
^ .. ■.' >'*^.^:c.«^ accurate quantitative de-
termination can be arrived
No. 27. ARTinciAL Cobalt Bute (same at. Where ultramarine blue
as uii;^- Wwc) — Phoiomicrograph jg mixed with lithoponc the
X2$o, crystalline grain. . 1 1 -j t ^.i i*.i
zmc sulphide oi the Iitho-
pone as well as the ultramarine evolve HjS, When deter-
mining the ultramarine, the total HiS evolved must be
calculated as sulphur. The zinc must be precipitated as
carbonate and weighed as oxid and calculated to sulphide.
The sulphur in the ZnS must then be deducted from
the total sulphur. From the difference the percentage
of ultramarine blue in the original pigment may be cal-
culated. As acetic acid liberates the H^S from the
ultramarine but docs not attack the S in lithopone, this
add may be used and the percentage of sulphur in the
ultramarine determined directly.
THE BLUE PIGMENTS 89
Ultramarine blue reacts wdth corroded white lead
but not with zinc oxid. It does not react very quickly
with sublimed lead or zinc lead, but for the making of
pale blue shades, which should remain permanent in the
package, zinc oxid is to be recommended in preference
to any other white pigment. Ultramarine blue should
not be mixed with any of the chrome yellows or chrome
greens, because a darkening effect is sure to take place.
Ultramarine blue behaves very badly with linseed oil
containing an excessive amount of lead drier. For mixed
paints of pale tints a resinate of manganese or oleate of
manganese drier is to be recommended. Most of the
Japan driers contain large quantities of lead, and a white
Japan composed of rosin, manganese and linseed oil wall
make the most permanent mixture.
Prussian Blue
Synonym : Milori Blue, Bronze Blue, Antwerp Blue, Chinese Blue,
Paris Blue, etc.
Almost every text-book on elementary chemistry
gives a description of Prussian blue, which is a ferri-ferro- /
c>'anide of iron, and in a general way it can be produced
for laboratory purposes by the simple mixture of ferro-
cyanide of potassium and a ferric salt of iron. Com-
mercially, the well-known ferric iron reaction of analytical
chemistry is reproduced on a large scale. Prussian blue,
however, is made from a ferrous salt and is obtained by
the mixture of ferrous sulphate (copperas) and ferro-
cyanide of soda or potash (yellow prussiate). This mixture
produces a pale bluish white flocculent precipitate, and the
chemist will easily understand how, with the addition of
any oxidizing agent, such as bleaching powder, potassium
chlorate, etc., the precipitate is converted from a bluish
white into a dark-blue pigment.
90 CHEMISTRY AND TECHNOLOGY OF PAINTS
There are a number of varieties of Prussian blue, all
approximating this composition but made differently,
being sold under the names of Steel blue, Milori blue,
Bronze blue, Antwerp blue, Chinese blue, and Paris blue.
Although each of these blues is chemically the same as
Prussian blue, they have different physical character-
istics. Prussian blue, for instance, is like a mixture of
indigo and black in its dry state, and when tinted with
one himdred times its own weight of zinc oxid the shade
produced is a muddy violet. Chinese blue, when treated
in the same manner, gives a purer blue which has no
trace of violet in the shade. The Steel blue, when diluted
one hundred times, gives a turquoise shade. And so for
the manufacturer of pale blue shades the tones of these
blues must be taken into consideration.
There is much discussion among paint manufacturers
as to whether Prussian blue is a permanent pigment or
not, and the author is frank to say that this matter can
be decided as follows : Prussian blue, or any of its varieties
may be considered permanent or fugitive, according to the
manner in which it is made and according to the base
with which it is mixed. If Prussian blue contains more
than a trace of soluble salt (sodium sulphate), it has a
decidedly yellowing action on the oil, and a light blue
or light green made of such Prussian blue is supposed to
be fugitive. On the other hand, a number of experi-
ments made with thoroughly washed Prussian blue have
demonstrated that it is a perfectly stable color and does
not change its shade. As a tinting color for making pale
blues in mixed paints Prussian blue has caused an enor-
mous amount of trouble. A pale blue mixed paint that
contains white lead in any proportion changes color in
the package, a reduction process taking place which
converts it from a ferric into a ferrous state, so that
THE BLUE PIGMENTS 91
when a can of light blue mixed paint made with Prussian
blue and white lead is opened it is a sickly green instead
of a blue. If such a paint be applied to an exterior
surface it is completely converted into its original blue
shade as soon as it is dry. The zinc oxid paints have the
same action, but to a very small degree, and a paint
manufacturer who desires to make a pale. blue by the use
of Prussian or Chinese blue must avoid the use of white
lead in his paint. The artificial cobalt blue mixed with
zinc oxid is, however, more desirable.
Prussian blue is also used in srriall quantities for mix-
ing with bone black to produce intensely black shades.
It is a simple matter to determine the presence of
Prussian blue in any pigment by the addition of caustic
soda to the dry extracted pigment, warming, filtering,
and testing the filtrate with a drop of ferric chloride after
acidifying. The Prussian blue made in laboratories
will contain approximately 30 per cent of iron, so that if
an analysis is made of a mixed paint tinted with Prussian
blue and the percentage of iron is multiplied by three, a
fairly correct estimate of the percentage of Prussian blue
is obtained; and while the factor given cannot be abso-
lutely correct, owing to the difference in the various
blues made, it is so nearly correct that a synthesis made
from such an analysis has invariably given the same
shade.
CHAPTER VIII
The Green Pigments
The greens used in the manufacture of paints are
the so-called chrome greens, which are mixtures of chrome
yellow and Prussian blue, the genuine chrome greens or
chromium oxid, the aniline lakes, zinc green, and the
verte antique or copper green.
Chrome Green
Chrome green is sold under various proprietary names,
and must not be confounded with the oxid of chromium.
Chrome green is essentially a mixture of Prussian blue
with chrome yellow, but the chrome greens, imless chemi-
cally pure, are always mixtures of blue and yellow on a
barytes or mixed base.
A green paint made entirely of Prussian blue, .chrome
yellow, and an inert base, such as silica or barytes, is
very easily analyzed by ignoring the pigment and weigh-
ing the base, calculating the pigment by difference. This
is, however, not a desirable method to reconunend except
in the hands of an expert who knows that the pigment or
])iiint is made on an inert base. Inasmuch as there is a
great \'aricty of shades of chrome green, ranging from a
yellowish green to a vcr}^ dark olive, and as the dark
slKides may he composed of either a mixture of orange,
elirome yellow, and Prussian blue, or a Ught chrome
yellow and Prussian blue and black, it is not safe to
nuillii)ly the percentage of iron by a factor to obtain the
l)er(entage of Prussian blue, because many shades of
THE GREEN PIGMENTS 93
green are produced with the use of ochre. The iron
factor would therefore be misleading. The lead chro-
mate can be washed out with hot hydrochloric acid and
will precipitate on cooling. The Prussian blue may be
washed out writh a caustjc alkali solution, the iron being
left behind, but it can be reprecipitated as Prussian blue
with a ferric salt, the necessary amount of chrome yellow
and Prussian blue originally used being thus recovered.
This method is uncertain only when an olive-yellow is
being analyzed.
Chrome green should never be mLxcd with white lead
for the pale shades, as it changes color in the can in
proportion to its content of Prussian blue. Zinc lead,
zinc oxid, sublimed lead, or lithopone should therefore
be used. If chrome green is not well washed the soluble
salts are likely to affect the linseed oil. At the seashore
the salt atmosphere invariably attacks chrome green and
bleaches it, and where an absolutely permanent green is
required chromium oxid should be used.
Chrgmiitii Oxid
Chemical Formula : Cr203
This green is one of the oldest greens in existence,
having been used for very many years, but never having
been used for mixed paints or by the paint manufacturer,
excepting for artists' use, until within the past six years.
WTiile it is expensive compared to the chrome green as
prexiously described, and while it is weaker in tinting
p>ower and lacks in brilliancy, it nevertheless is the only
perfectly permanent green made. It mixes with every
other pigment without decomposition and stands the
light without fading or darkening. No alkali discolors
it, and therefore in the modem flat wall paints where
delicate greens are desired chromium oxid has come to
04 CBEJiiSTRY AND TECHNOLOGY OF PAINTS
pby 4L \x^n* significant role. Many manufacturers get
KXK^ tW their fancy colors, such as greens, blues, and ver-
m3iv>tt:s iind any man who makes a perfectly alkali-proof
xi;j^tl jxAint is entitled to a higher price if the goods are
IvUcr than those of his competitor.
i^hr\>mium oxid frequently possesses coarse qualities.
It 15^ made as follows i^
Kight i>iirts potassium dichromate and 3 parts of pure
tKuie iiciil are ground with water to a stiff paste. The
uuxlviu* is then heated to dull redness for about 4 hours
\\\ u rexerberatory furnace. The melt is thrown into
wuler and boiled, to decompose borates of chromium and
lK>lassium into boric acid and chromium oxid (hydrated).
V\w latter is then washed, dried, and ground.
After it comes out of the dry room it has to be ground
in a burr stone mill with water exactly like an oil color.
This develops whatever brilliancy there is in the color
and increases its hiding power, but unfortunately it also
develops a ** float'' of a very much more brilliant green
than the natural chromium oxid. This float is similar
\\\ color to the well-known Veronese green or hydrated
oxid of chromium, but is not apparent in the quicker
drying types of paints.
Chromium oxid is now largely used as a basic color
\\\ automobile painting, particularly in the painting of
llu' hoods, and also for the manufacture of the best
Ispr of chirk green engine enamels, because excessive
luuilinKi ^^^ alternate heating and cooling, does not affect
i( ill rtluide as it does the chrome green made from yellow
•mmI hiiir.
riuii' is every reason to believe that this pigment
^vlll hi' um'tl in greater quantities than it has been because
(i| ih) hUMling (|ualities.
* Chem. Ztg. 9, 851.
the green figments 95
Green Aniline Lakes
Flat wall paints, which are very largely used in
America, are the cause of the manufacture of certain
green aniline lakes which are not permanent to strong
light but are permanent to alkali, and are therefore used
to some extent for making very brilliant green house
paints for interior decoration.
These lakes can be readily tested by mixing them
with soapy water and lime, and if they remain un-
changed for five minutes they may be regarded as
permanent, because the majority of the aniline lakes
which are not alkali-proof are immediately converted
into a yellow or yellowish brown color when mixed
wath this reagent.
The aniline lakes have no hiding power, but have
tinting strength, and are only used as tints. For making
ver>^ brilliant greens that have hiding power the chromium
oxid is used as a base and the aniline colors to obtain
brilliancy.
Zinc Green
Zinc greens are generally mixtures of chromate of zinc
and Prussian blue, and are extremely brilliant, perma-
nent to light, but not permanent to alkali or to water,
as the chromate of zinc remains slightly soluble imder
many conditions.
This particular type of green is also largely used for
interior decorative purposes and for the manufacture of
flat wall paints. It is much more expensive than the
chromate of lead green. It is also used to some extent
as a coach color. Where it is varnished over this color
is not soluble.
96 chemistry and technology of paints
Verte Antique (Copper Green)
The pigment for making verte antique or antique
green for copper imitation is generally the bicarbonate of
copper. It has little or no hiding power, but the corroded
copper effect cannot be very well imitated with any other
pigment. It is manufactured as follows:
A solution of blue vitriol is precipitated with sodium
carbonate, yielding a basic copper carbonate, carbon
dioxid being evolved in the course of the reaction.
2CUSO4 -f 2Na2C03 + H2O = CuCOa- Cu(0H)2 -f 2Na2S04 + COj
There are a number of other methods in use for
making copper green which are more lengthy and trouble-
some to carry out.
The lack of hiding power of this color is one of its
good qualities, because the under coat usually is a copper
color, made by so mixing a para toner and Princess Metal-
lic brown that the translucency of the bicarbonate of
copper gives the effect of actually corroded copper.
Frequently this color is stippled on, and sometimes it it
flowed on. Where opacity or hiding power is wanted
chromium oxid and bicarbonate of copper are mixed.
This pigment is permanent to light, and is at present
practically the only pigment made or used which con-
tains copper.
CHAPTER IX
The Black Pigments
The principal dry pigments used in making black
paint are as follows:
Lampblack Vine Black Black Toner
Carbon Black Coal Benzol Black
Graphite Ivory Black Acetylene Black
Charcoal Drop Black Mineral Black
There are quite a large variety of bone blacks, begin-
ning vdih ivory black and going down to the by-product
of the sugar mills known as "Sugar House black." In
composition all of the animal blacks are alike, in so far
as they always contain carbon and calcium phosphate.
The carbon varies between 15 and 23 per cent, the
rest being phosphate of hme and moisture. Some of
the best blacks used for mixed paints are made from
the shin-bone and skull of. the sheep, it ha\dng been
found that these blacks are of the most intense color.
Occasionally variable amounts of calcium carbonate are
found in these blacks, depending largely upon the length
of time the bone was burned. For making a verj'^ intense
and good quality black which w^ill not settle when mixed
with varnish, carefully selected bones or burnt ivory
chips are taken, and digested in hydrochloric acid, w^hich
removes all the lime salts and leaves the carbon as a
flocculent residue. This carbon is probably the highest
priced and most intense black used by paint makers,
97
98 CHEMISTRY AND TECHNOLOGY OF PAINTS
and is frequently sold under the name of black toner,
because it sometimes is used for giving an intense tone
to an otherwise pure black. In the material known as
Black Color in Varnish, it is found that black tone
serves its purpose best, and a black paint which is con-
posed of black toner groimd in linseed oil and redticed
with a very high grade of coach varnish is worth from
$4 to $6 per gallon.
Lampblack
Lampblack is the condensed smoke of a carbonaceous
flame, and at present is made from a hydrocarbon oil
of the type of dead oil, or it may be made from a number
of distillates which on burning give a condensed black
soot. Lampblack is still made from resinous woods,
tar and pitch where the dead oil is not obtainable, and
while many people are inclined to regard lampblack and
carbon black as the same, they are not by any means the
same from the paint manufacturer's standpoint, for lamp-
black is distinctly gray when compared with ivory black,
bone black, or carbon black, and as a general rule lamp-
black makes a bluish gray when tinted out with white,
one hundred parts to one, whereas bone black and ivory
black as a rule make a brownish tint. This is an empiri-
cal method for differentiating them.
The specific gravity of lampblack is generally less than
two, and one pound of a very pure lampblack without
undue pressure will fill a package which is over 200
cubic inches in size, and very often over 230 cubic
inches or one American gallon.
Lampblack is distinctly an American product, as is
e\adenced by the enormous amount of blacks of this t3Tpe
which are exported; a careful search of the imports fails
THE BLACK PIGMENTS 99
to show any appreciable amount which comes into this
country.'
Lampblack as it is made now is exceptionally pure,
and contains more than 99 per cent of carbon. Occasion-
ally, however, samples are found which contain a small
percentage of unbumed or condensed oil, which will
retard the drying of lampblack to such an extent as to
make it at times unfit for use. Prior to 1906 there were
many cases where lampblack contained unsaponifiable
grease, and the author de-
vised a method for remov-
ing this with 62° naphtha,
changing the slow drying
lampblack into one which ,
dried definitely; but since 1
that time, due to improve- '
ments in the selection of
lampblack and the greater
care taken in its manu-
facture, it is very difficult
to find a lampblack which
contains less than 99.5 per ^°- '^ L«a.«"CK-rhotomicn>gmph
'^ -J t^ X300, very uniform,
cent carbon and which
does not dry within a reasonable time. It must be taken
into account that lampblack is always a slow drier.
Whether this is due to the fact that it prevents the blue
rays of light from entering the oil, or whether it is an
inherent paralysis, has not been definitely decided, but one
thing is positive, that where lampblack contains unbumed
or condensed oil the drying is in a large measure paralyzed.
' A most escellent historical treatise on lamp and carbon blacks
will be found in the original communications of the Eighth Inter-
national Congress of Applied Chemistry, Volume 12, page 13, by
Godfrey L. Cabcrt.
^«a55.^
CHEMISTRY AND TECHNOLOGY OF PAINTS
Carbon Black
Carbon black is in ail respects similar to lampblack,
except that it is intensely black in color, and while it
shows no crystalline structure under the microscope it
condenses itself so hard on the places from which it is
scraped that it is largely interspersed with flakes of black
which to all appearance are crystalline and are verj-
refractory in the mill. Its tinctorial power is very great,
one pound being sufficient
to tint one hundred pounds
of white lead to a dark
gray. Paint manufacturers
have, however, abandoned
[ its use as a tinctorial ma-
terial for several reasons,
the principal ones being
that it is likely to produce
a streaky color when used
as a tint, owing to the pres-
ence of very small nodules
that do not show up untU
it is applied as a paint
(and these streaks cannot be brushed out). In the
second place it shows a peculiar tendency to attach
itself to minute air bubbles, so that when made into a
mixed paint of a lighter tint and allowed to stand in the
package for a considerable time, fairly large amounts of
black rise to the top of the liquid. Only with the great-
est difficulty can these be remixed mth the rest of the
pigment to produce a uniform tint.
No. ag. Carbon Black — Photomicro-
graph xjoo, very uniform.
THE BLACK PICMEXTS
Graphite
Synonym : Black Lead, Stove Polish. Specific Gra\-ity : 1.19 to 2.5,
depending upon the impurities contained in it ■
Graphite is found as a mineral almost all over the
world. It is ver>' largely used as a paint pigment, and
it is remarkable that in its natural state it has all the
defects of bulkiness which red lead has for weight. The
purer a paint jiigment is as to its content of carbon the
piKircr is the paint pro-
duced. If graphite be taken
with a content of 80 or 90
per cent carbon and mixed
with linseed oil, it forms a ii
porous, flufly film, and the
). jo. Xatlrai. Gh,\pjiiie — I'holo-
inicrograph X150, containing about
40 per cent of silica, showing crystals
of silica and graphite.
particles of graphite coagu-
late in the linseed oil and
produce a very unsatisfac-
torj- covering. If graphite
be diluted with a heavier
base its weakness then be-
comes its strength and a
verj- good paint is formed.
Many of the characteristic
chemical and physical defects of red lead are largely
reduced and frequently eliminated when it is mixed in
proper proportion with graphite, a high grade of graphite
when finely ground with linseed oil acting as a lubricant
and sliding under the brush.
Pure graphite, as is well known, will co\-er from 1000
to 1600 square feet to the gallon. Such a paint film is
so exceedingly thin that, while it looks good to the eye,
in a short period decomposition more easily takes place
beneath it than beneath many poorer paints. It is there-
I02 CHEMISTRY AND TECHNOLOGY OF PAINTS
fore essential to reduce graphite with a hea\aer base, and
to this end it has been found that a mixture of silica
and graphite produces very good results; but even this
paint has the objection of ha\Tng too much spreading
power.
^lisnomers have crept into the paint trade in regard
to graphite paints, such names as green graphite, red
graphite, browTi graphite, etc., being in use, when in
reality such graphites do not exist, excepting as far as
graphite has been mixed with pigments of these colors.
A six-year test of a
linseed oil paint made with
^ ^^^ ^ ' %m\^ ^ neutral ferric oxid, con-
M j^ ^ it g'^. taining in its composition
^ *W S ^5 P^^ ^^^^ ferric oxid and
w • «^ \^ <iii» tgr ^^ P^^ ^^^^ silica mixed
JC. • «y ^ ■ with graphite containing 85
■ffigf^ ^^4^ ' * '*•' P^r cent graphitic carbon,
gi^ 3a%J^ ^^ ^^^ proved itself to be as
V* ^V good a paint as can be
^^|N^ ,P^ desired for ordinary'- pur-
poses. The pigment in a
No. 31. Natural Graphite — 90 per . . . i • j -ii
ccnl carbon, very finely i)o\vdcre<l. pamt Ot thlS kmd Will
withstand the chemical ac-
tion of gases and fumes, but the oil vehicle is its weakest
part.
Since the electro-chemical industry has been developed
at Niagara Falls graphite has been made artificially and
is sold under the name of *^\cheson Graphite." This
graphite is to be commended as a paint material on
account of its uniformity and fineness of grain, but it
should not be used alone as a pigment, for as such it
possesses the physical defect of lightness just described.
A graphite paint containing more than 60 per cent graph-
s.
THE BLACK PIGMENTS 103
ite does not serve its purpose very well unless 40 per
cent of heavy pigment is added, such as a lead or a zinc
compound. A rather unfortunate defect in the graphite
paints containing a large amount of graphite is the
smooth and satin-like condition of the paint film, which
is poorly adapted for repainting. It has often been
noted that a good slow-drying Imseed oil paint will curl
up when applied over certain graphite paints, because
it does not adhere to the graphite film. On the other
hand, if particular forms of
calcium carbonate, silica,
or ferric oxid are added
to graphite a surface is
presented which has a
"tooth," to which succeed-
ing films adhere very well.
The question of the co-
efficient of expansion in
paints has not been thor-
oughly considered, and
many a good paint will No. 32. ARnnciAL Graphite (Acheson)
fail because it is too elastic. -" Photomicrograph XJjo, conuin-
, . ing go per cent uf carbon.
Engineers sometmies pre-
fer a paint which when scraped with a knife blade
will curl up like ribbon. Priming coats suffer very
much when they are as elastic as this, but the paint
chemist can overcome these defects by the proper ad-
mixture of inert fillers and hard drying oils.
Graphite is known as a very slow drier, but this is
true only when too much graphite is used in the paint.
There is no reason why a graphite paint should not be
made to dry sufficiently hard for repainting within
twenty-four hours.
CHEMISTRY AND TECHNOLOGY OF PAINTS
It is not generally known that charcoal from the
willow, maple, and bass trees is largely used as a pigment
for black paints. There are a number of black paints
on the market which are composed of charcoal, lampblack,
litharge, and linseed oil in varjing proportions, and in
the early history of these paints it was difficult to make
them so thin that they would not turn semi-solid in the
.Mu «^ package. It was found that
«i*i^Ait^'-* f^ as a preservative coating
•\^^ *T ,-,*'>* on steel they did remark-
jf^SC^'^i^t^ ^^'^' ^^■^'*' Investigations
^^^^^3^^eiS ^^ ^^^ author have shown
** Sj^ %i^*'3^ jiXf"^ ^^^^ ''^'^ preservative ac-
^ ( »1?-J*V**>S' •'5*i' tion is incidental and is
f due entirely to the alkali
contained in the charcoal.
Some of the charcoal used
'■'O uJC*>^" "^ ^^ ^ b\-prcduct from paper
No. 33- Artifici.u. tiH,\Pi!iTE (Ache- mills and contains as high
son) — Photomicrograph xis°, "»'- as 2 per cent of potassium
carbonate. In fact, the
carbonate is produced by the burning or calcining of wood,
most charcoal being more or less alkaline. In the exami-
nation of paints of this character it was noticed that the
spectroscope showed the potash lines, and thus it became a
very simple matter to determine by means of the spectro-
scope whether a paint was a charcoal paint or not. The
author has demonstrated on pre\'ious occasions that the
oxidation of metal cannot take place in the presence of
certain alkalies, and therefore these charcoal paints when
freshl)' made are excellent preservati\'es for the metal. But,
inasmuch as moisture is always present in these paints,
THE BLACK PIGMENTS 103
ha\Tng been added in the form of water or contained in
the raw materials, saponification takes place more or less
rapidly, so that the paints
are sometimes unfit for
use two months after they
are made.
The charcoal above re-
ferred to, which is the
b>-product from the paper
mills, while not so suitable
for the manufacture of " j . j^
mixed paints, has, however, ■ ^ ' ^. ' ■ V
been verj- largely used in ^ v
the manufacture of oilcloth -. . ~ '^p,
and coated leather. graiili x6oo.
VixE Black
In all essentials this pigment is the same as the pow-
dered charcoals for paint
purposes, excepting that
A^ , the grain is smaller and the
tij^ J| ► black denser. It is made
^v • ^ *" , • \ in German}' bj- charring
- ^fe - ^^^^j^iTl the grajjeNine. If o\er-
m
j charred it is likely to
become too alkaline. The
same tests may be applied
to this black which were
--^^ ^ .*'.^ -'"^' used for all the charcoal
No. 35- Charcoal Black - Phoiomi- and WOod pulp blacks, the
crograph x6oo, showing hexagonal simplest and most effec-
stmcturc ol the wood. ^j^.^ j^g^ ^^^^ ^^ j^^jj ^^^
black in water, filter, and add a few drops of phenol-
phthalein.
CHEMISTRY AND TECHNOLOGY OF PAINTS
Coal
Powdered anthracite and bituminous coal are likewise
used in black paints, but the origin of their use is due to
some extent to poorly written paint specifications. An
engineer will at times prescribe a paint containing a cer-
tain percentage of ash, and in order to meet this require-
ment a paint manufacturer will have to add coal in order
to conform with the requirements, but as sulphur com-
pounds such as SOj and S0»
always exist in coal a paint
is produced which is ex-
ceedingly harmful to metal.
Ivory Black
Ivory black is still used
to some extent for very
intense coach colors, and
there is also a very fine
species of carbon black on
■ the market known as the
"Extract of Ivory Black,"
which is made by digesting
charred ivory chips in hydrochloric acid until nearly all
of the calcium phosphate is dissolved. Such a black has
intense staining power, and is b}- far the blackest material
made. It is very expensi\'e, colloidal in its nature, and
used therefore for ready prepared color-in-varmsh or high
grade black enamels.
^
No. 36. \1NE IfLACK (
(icrman make) -
Photomicrograph x.
Rrain.
2SO, two sizes 1
Drop Black
Drop black is generally made by calcining sheep bones,
which are then impalpably ground in water, and when in
THE BLACK PIGMENTS 107
paste form cast into small drops; hence its name, "Drop
Black." These cone-shaped drops were largely used
twenty-five years ago, and then were an indication of a
good black, but at present the name "Drop Black"
still clings to finely powdered bone black. So-called
drop black is generally composed of from lo to 20 per
cent of carbon and from 80 to 90 per cent of cal-
cium phosphate, and is sold entirely for its intensity of
blackness.
Black Toner
Black toners may be either the extract of ivory
black, the extract of bone black, or certain forms of
carbon black, or carbon
black upon which nigro-
sine has been precipitated.
Another method for mak-
ing black toner is to
precipitate red, yellow, and
blue aniline upon the ex-
tract of ivory black, which
produces an intensely
black pigment that is
flocculent and remains
in suspension a long time.
The principal difficulties
with these coal tar blacks, ^™"''
however, are : first, they are not really black in the
sunlight; and second, they paralyze the drjing quality
of any varnish with which they may be mixed. There
are a number of specially fine blacks that can be used for
black toners, such as condensed carbon from benzol or
acetylene. Benzol black is remarkably fine and intensely
No. 37. WiM)D Pule
micrograph X500,
II LACK — J'hoto-
k-ery tine uniform
lo8
CHEMISTRY AND TECBNOWGY OF PAINTS
5->v
^
black, and inasmuch as there may be an overproduction
of benzol in the United States within the next few
years it is very likely that benzol black will become a
reasonable article of commerce.
Benzol Black
Benzol black is a carbon
black which, however, is
much better than the car-
bon black produced from
natural gas. It is soft,
contains no granular par-
ticles, and remains in sus-
pension for many weeks
in both oil and varnish.
It is, however, a very poor
drier, like most of these
blacks, and therefore a
mixture of litharge and red lead oil is recommended
when they are to be used.
Acetylene Bl.\ck
This black is not quite
as common as it was some
years ago. It has very
desirable properties and
can be used for tinting
])ur])oscs without showing
granules or streaks, as is
often the case with car-
bon black made from
gas. It is flocculent and somewhat colloidal in
No. jS. Dh(.p
graph X300. Ti'
i — Photomkro-
;ly powdered.
the black pigments 109
Mineral Black
Mineral black is usually composed of hea\'y black
slate, more or less finely ground, and as a paint pigment is
inert. It is often toned with lighter (in specific gravity)
carbons and lampblacks, but is not largely used on
account of its destructive action on paint mills. Where
iron paint mills are used these mineral blacks are found
to be very expensive, because they wU dull the sharpest
mill in a few hours' run. As they possess very little
tinctorial power it is more advantageous to use a 200-
mesh silica, tinted with lampblack.
CHAPTER X
The Inert Fillers and Extenders
These materials, which at times have been called the
"reenforcing pigments/' have their value when used in
moderate proportions, and yet it is not within the
province of any paint chemist to say to what extent
these materials can be classed as adulterants and to
what extent they can be classed as inert fillers or reen-
forcing pigments. In every case where this question
comes up common sense, judgment, and best practice
provide the answer.
In the manufacture of mixed paints, with one excep-
tion which \vill be described later, every mixed paint
must contain an inert filler or extender, or else the paint
will not remain in a ready-to-use form, but will set hard
and lose much of its value. In white paints 45 per cent
of zinc, 45 per cent of lead, and 10 per cent of asbestine
are regarded as a standard formula, and 60 per cent of
these pigments are usually mixed with 40 per cent of oil
to produce the proper kind of paint. There are many
instances where the inert fillers may reach as high as 20
per cent, that is, to 40 per cent of zinc apd 40 per cent
of lead or other white pigments, 10 per cent of gypsum
and 10 per cent of white mineral primer, are added in
order to give certain physical results; and yet there are
any number of instances where more than half of the
paint in question is composed of an inert filler, and the
inert fillers under those circumstances cannot be regarded
THE INERT FILLERS AND EXTENDERS III
as adulterants. If we make a ready mixed paint of
ochre we are taking a natural pigment which contains
So per cent of clay, and no man can say that the clay
naturally contained in ochre is an adulterant. In the
manufacture of a flat wall paint in which lithopone is
the principal pigment we have a pigment which contains
70 per cent of artificial barium sulphate, and yet no man
can say that this artificial barium sulphate is an adul-
terant. In the Battleship Gray paint which the author
de\ased for the United States Navy, it was found that
the 45 per cent of zinc and 45 per cent of lead, with the
addition of 10 per cent of black coloring matter, which
was formerly used, gave very poor results, for such a
paint was not salt-water-proof nor resistant to abrasion;
but since the United States Navy has adopted the for-
mula made by the author of 45 per cent of zinc oxid, 45
per cent of blanc fixe, and 10 per cent of graphite and
lampblack, a far better paint is produced which costs
the Navy very much less money than the old type of
paint. It is therefore not within the province of any man
to say that the addition of this 45 per cent of blanc fixe
constitutes an adulterant. Judgment, common sense, and
the particular case involved must therefore decide the
difference between pigment and adulterant. A large
number of other cases can be cited, but these are suf-
ficient to illustrate the point.
The principal paint made which contains no extender
and which remains in suspension is the well-known white
enamel paint composed entirely of zinc, in which the
medium is either a heavy bodied oil or a damar varnish.
This paint needs no extender to keep it in suspension,
on account of the very slight chemical action that takes
• place between the acids in the oil or varnish and the zinc
! itself.
112 CHEMISTRY AND TECHNOLOGY OF PAINTS
In spite of all the good qualities of white lead it has
been impossible up to now to manufacture a ready mixed
paint composed entirely of white lead without the help
of an extender like asbestine or a slight saponification
or emulsification by the addition of about i per cent of
water.
It is not so difficult to decide what constitutes an
adulteration if we take the simple case of ready mixed
white paint intended as a priming coat, which should
have the maximum hiding power and physical qualities.
If a paint like that were composed of 50 per cent white
pigment and 50 per cent of barytes or whiting, it would
not possess the physical qualities necessary for a good
priming paint, and therefore the addition of this quantity
of barytes would be strictly regarded as an adulterant.
The principal fillers used in the manufacture of paints
are as follows:
Barytes Calcium Sulphate
Barium Sulphate^ {Artificial) Clay
Barium Carbonate Kaolin
Silica Asbestine
Infusorial Earth White Mineral Primer
Calcium Carbonate Whiting
G>'psum
Barytes (Barium Sulphate, Natural)
Formula, BaS04; Specific Gravity, 4.5
Barytes is a white mineral having the same chemical
composition as precipitated barium sulphate. In the
United States Geological Survey Reports for 1904, the
following statement occurs: *^The value of barytes as a
white pigment is being recognized more and more each
year, and although very little, if any, is used alone for
this purpose, it is used in large quantities in combination
THE INERT FILLERS AND EXTENDERS 113
with white lead, zinc white, or a combination of both of
these white pigments. This addition is not considered
an adulteration, as was the case a few years ago, for it
is now appreciated that the addition of barytes makes a
white pigment more permanent, less likely to be attacked
by acids, and freer from discoloration than when white
lead is used alone. It is also believed that barytes
gives greater body to the paint and makes it more
resistant to the influences of the weather. As is well
known, pure white lead
when remaining in the
shade or in a dark place
becomes discolored, turn- /^•a'^*S ••.'i? *» W\
ing yellowish, while mix- //^ •• v '.* j,v ^ * * »!
tures of white lead and
zinc white, or white lead '•-T"'^(ft«#
and barytes, or white lead,
zinc white, and barytes T* •.».?- ^,
retain their- color perma- ^^'^^^t' VVa^*
nentlyeven in dark places," ^<t '. *. ' . •
The amount of barytes
^, ^ 1 -J .., No. 40. BAkYTES, irragular, broken crys-
that can be mixed with uu-Ph^tomic^ph xjoo.
colored pigments without
injuring them is remarkably large. There are hundreds
of brands of para-red paints made and consumed every
year by the agricultural implement trade which contain
as high as 90 per cent of natural barytes. When it is
taken into consideration that these extremely diluted
para-reds cover well and serve their purpose most admir-
ably, the expert should be very careful not to condemn
bar>'tes when used in large quantities, for this remarkable
behavior is repeated with a large number of other pigments.
No paint chemist will dispute the fact that barytes
adds wearing quaUty to paint, but inasmuch as white
114 CHEMISTRY AND TECHNOLOGY OF PAINTS
lead has set the. standard for ease of working it is ad-
mitted that all the other pigments and fillers are not as
unctuous as white lead. Therefore the house painter
will notice that the so-called lead combination^ which
contains large quantities of barjrtes^ does not work is
freely under the brush as white lead; nevertheless^ this f
objection does not hold good when the barytes is used
in moderate quantities, that is, not in excess of one third '.
of the total pigment of a paint. An experiment was
made with a mixture of one third carbonate of lead, one
third zinc oxid, and one third barytes on an exposed wall
of a high building in New York City, in 1885.^ Up to
1905 this surface was still in a moderately good state of
preservation, and as a comparison a wall painted in 1900
with a -pure Dutch process white lead showed that the
Dutch process white lead had not stood as well in five
years as the combination mixture had stood for twenty
years. It is conceded that no paint is supposed to last
twenty years, but as a matter of record it is interesting
to note that the inert filler added so much to the life of
the paint which contained it. In view of this fact, the
paint manufacturer is justified in recommending to his
customers the use of inert fillers in his paint on the
ground of increased longevity.
One hundred pounds of barj^s will yield two and
three-quarters gallons of paint. Owing to its crystalline
structure and specific gravity it is a more expensive pig-
ment to use than many others when sold by volume, and
a paint manufacturer who uses barytes in a mixed p>aint
and thinks he is the financial gainer thereby is very much
mistaken, owing to the small volume which barytes . occu-
pies in a mixed paint. It is also interesting to note from
an experimental standpoint that if barytes be mixed with
^ This building was demolished in 1908.
THE INERT FILLERS AND EXTENDERS 115
linseed oil and turpentine in the proportion of two pounds
to a gallon it will be found that, on allowing these two
pounds to settle in a glass jar where it can be observed,
it occupies only 4 per cent of the bulk. In spite of
much that may be said in favor of barytes, it is not
better than some of the forms of calcium carbonate and
some of the forms of silica. As an inert extender silica
has advantages over barytes; namely, that while it
produces the same physical effects with equal wearing
quality, its cost is lower
and it produces a surface ^ J!t^ J^^
for repainting, having what
is' technically known as
"tooth."
Barytes is made from
the mineral barite, and
the principal deposits in
the United States which
are worked at present are \**^s ^'-"^l^*^*^^^
in Missouri, Tennessee, and '^(f%^ % •• •
Kentucky. There are also *~
deposits in Virginia and ^^- ^'' ^^^^^""-^^ American- Photo-
*^ ^ ® micrograph X300.
in Georgia, and large
amounts are also found west of the Mississippi, but
freight plays a very important role in the shipping
of barytes, and furthermore, only those mines nearest
the surface can be worked at a profit. Barytes is not
foimd in ledges or solid masses, but rather in isolated
nodules. The pieces vary in size from an onion to a
man's head, and vary in weight from one ounce to
twenty or twenty-five poimds. There are, of course,
larger isolated lumps foimd, but generally speaking this
is the manner in which the material is mined. The
mining of barite, as a general rule, is simply done in an
Il6 CHEMISTRY AND TECHNOLOGY OF PAINTS
open cut, and much of the barytes found in the United
States is associated with a material called "chirt," which
looks like barytes but can be very easily distinguished
on account of its difference in weight. Chirt is a silicate
of magnesia and alumina, and workmen very soon be-
come adept in separating chirt from barite. Barite is
usually contaminated with iron or with a sticky ferru-
ginous clay, which can be separated by weathering or
by washing. Some of the deposits in Virginia and
Kentucky contain more than i per cent of lime and
fluorine, which makes the ore undesirable for manu-
facturing purposes but is not supposed to render it value-
less as a paint base. To free it from iron it is bleached
by what is known as the sulphuric acid process, but as
it is generally washed, lixiviated, and floated after this
treatment it is very seldom contaminated with any
degree of acid.
Barium Sulphate (Artificial)
Synonym: Blanc Fixe, Lake Base, Permanent White;
Specific Gravity, 4.1-4.2
When a solution of chloride of barium is mixed wath a
solution of sulphate of soda a heavy white precipitate is
formed w^hich is known as artificial barium sulphate.
In all of its chemical qualities it is identical with the
barytes of nature, but in its physical qualities it is
totally different. Depending somewhat on the method
of its manufacture, the grain is exceedingly fine.
Blanc Fixe has for years been used for the surface
coating of paper, because when properly calendered it
gives a very high polish and a permanent white surface.
Originally it was a French product, the words "Blanc
Fixe" meaning ^^ permanent white.'' In the early days
of the paper industry various compounds of bismuth were
THE INERT FILLERS AXD EXTE.WDERS
117
iised for coating the paper. There are still visiting cards
in existence which were surface-coated by means of bis-
muth carbonate and bismuth subnitrate. These cards
were readily affected by sulphur gases, and when it
was found that precipitated barium sulphate produced
an equally high glaze and the surface retained its pris-
tine whiteness the name "Blanc Fixe" was universally
adopted for the new product.
In the paint industry it was recognized that pre-
cipitated barium sulphate
was a valuable adjunct in
the manufacture of paint,
owing to the fineness of
the grain and other physi-
cal characteristics of the
material. It was found,
however, that when it was
dried and powdered it had
lost its extreme fineness
and did not mix readily • I'v^^S" ;
with oil paints. In 1895 N0.42. Blanc Fixe — Photomicrograph
Henry M. Toch succeeded X3™- PtecipiUled from cold, dilute
, . —., ■_. barium chloride.
m making Blanc Fixe,
which, when dry, was a soft, impalpable powder of
great value as a base upon which to precipitate lakes,
and, likewise, when used in mixed paints and enamels
imparted to them, under proper conditions, a vitreous
surface which improved their wearing quality. To this
product the name of Lake Base was given. A great
many paint and chemical concerns have succeeded since
then in producing Lake Base of a soft fine texture, and
it has become one of the established bases of the paint
trade. Its intrinsic value, when properly made, is about
half that of American zinc oxid, but a number of writers
Ii8 CHEMISTRY AND TECHNOWGY OF PAINTS
have erroneously stated that its body and covering
capacity were equal to. zinc oxid. Lake Base is success-
fully used up to 70 per cent in white pigments, and in
colored pigments up to 95 per cent. It is amorphous
under the microscope, and is used to a great extent to
increase the spreading of weaker or coarser colors.
Since 1906 artificial bariimi sulphate or Blanc Fixe
has been used by nearly every paint manufacturer in the
United States, for its excellent quahties have been proved
beyond a doubt. The value of this material as a reen-
forcing pigment or filler in the manufacture of paints has
been thoroughly demonstrated by the elaborate experi-
ments made by the United States Navy, another indica-
tion of how futile it is for any man to say without careful
consideration what shall be regarded as an adulterant
and what shall be regarded as a piure material. In 1910
the Bureau of Construction and Repair of the United
States Navy had come to the conclusion that the Bat-
tleship Gray, which had been in use since the termina-
tion of the Spanish- American war — a period of about
ten years — did not give good results. The formula for
the Battleship Gray as it then existed was practically
45 per cent of white lead, 45 per cent of zinc oxid, and
10 per cent of lampblack. From the standpoint of purity
this should be regarded as a very pure paint, and frora
all precedent it should be inferred that a paint of this
tyxxt would be the best that could be made; but two
things demonstrated themselves beyond peradyenture.
One was that such a paint was not hard enough to resist
abrasion; furthermore, salt water in the form of spray
or the water itself had a decidedly bad effect. When a
paint of this tj^^e became wet it absorbed water, changed
its color, and became very soft and spongy. The Navy
officials most interested in this consulted the author, who
THE INERT FILLERS AND EXTENDERS 119
devised a paint which then would probably have been
condemned by painters in general. Previous experience,
however, had taught that the addition of large quantities
of artificial barium sulphate or Lake Base to a proper
pigment improved the entire value of the paint, to say
nothing of reducing its cost over 20 per cent. As a result
the formula decided upon by the author was: 45 per
cent of zinc oxid, 45 per cent of Blanc Fixe or Lake Base,
and 10 per cent of graphite and lampblack. The proper
oils and driers were then added. A three months' test
was made on the machine repair ship "Panther," and
when this ship came back from a cruise it was found that
the paint was sufficiently hard so that the anchor chains
rubbing against the paint did not abrade it, and that
the salt water, wherever it had wet the paint, did not
produce any effect whatever. For upward of a year
the Navy experimented in a small way painting other
ships, imtil in 191 5 as much as several hundred thousand
pounds of Blanc Fixe had been bought by the Navy for
the manufacture of Battleship Gray. There may come
a time when a new paint superior to the present one
wall be devised, but this much has been absolutely proved
— that a mixture of 45 per cent of zinc and 45 per cent
of Blanc Fixe for sea water purposes is far better than a
similar mixture made of zinc and lead only.
At the time the Navy formula was originated Blanc Fixe
was worth about 2 cents per pound, which made a con-
siderable saving to the Navy. At the present writing,
owing to the European war and the fact that only one
concern is at present manufacturing Blanc Fixe in the
United States from American materials, and that the de-
mand is great and the supply small, the price has risen
to over $85 per ton. If the price should rise as high
as zinc oxid or lead itself, it is quite obvdous that in view
^ decompi
^^i^'J^/ ■***•/»;.•.•. stood thi
*^^?-- .' ' A. t? * ♦ , ,■». •■ condemni
•'iT • - .. •-* i'"^ '^'^^Sar written t<
IZO CHEMISTRY AND TECHNOLOGY OF PAINTS
of the purity of a paint made of Blanc Fixe the ques-
tion of adulteration could not enter. It will therefore
be seen that this question of adulterated pigments is all
relative, depending entirely upon the results obtained and
upon the cost of the material.
As far as the influence of salt water on a paint made
of Blanc Fixe is concerned, the writer had determined
long ago that the action of sodium chloride (salt)' in the
air or in water is one of the causes of the chalking or
decomposition of white
t must not be under-
that the author is
condemning white lead as
i pigment. This is simply
"irtpf* , written to show that there
i-'*'.*.' **■"<■*' "".".■.•■ V ." ^^^ instances when other
*. V, *'*•■'■■■* * •'ii.'v V I materials are better for a
. '^■*y /^ .' ' '' .tf^y given purpose.
•** ■' ^ k- > V'^- • Dry Blanc Fixe is des-
* '**^ i"**'- ' tined to become a very
,, „ ^ ' Du . ■ u useful paint material. In
No. 43. Blanc Fixe— Photomjcrograph '^
X300. Prccipitaied from hot, con- 1905 there were probably
centratcd acid solution of barium n^^ 0^^^ j^jq ^Q^g ^^
chloride. , ,
year used. In 1915 the
use had risen to over 3000 tons per year, because the
textile manufacturers had also found that its use in
materials like linoleum and table oilcloth not only saved
in cost of manufacture over the higher priced pigments,
but produced more flexible and lasting materials. The
same can be said of the printing ink manufacturers, who
today are as large consumers of dry Blanc Fixe as the
paint manufacturers.
As regards the manufacture of Blanc Fixe, this has
also changed within the last ten years. Formerly it was
THE INERT FILLERS AND EXTENDERS 121
known that only a solution of barium chloride and a
soluble sulphate or sulphuric acid were the raw materials
used for making this product, but today there are other
methods which produce equally good materials, and in
some instances better results than the chloride method.
For instance, bariiun sulphide solution is precipitated
with sodium sulphate, yielding a by-product, sodium
sulphide, which can be sold at a considerable profit.
The Blanc Fixe so made is denser than that made from
the chloride. Blanc Fixe is also made from the peroxid
of barium and sulphuric acid, but must be neutralized
and freed from peroxid of barium before it is suitable for
paint purposes. For certain color purposes the material
is made from concentrated hot solutions, which produces a
crystalline Blanc Fixe valuable for very brilliant colors,
particularly greens and reds. Another method used is
dissolving barium carbonate in nitric acid and precipi-
tating with sulphate of soda, which then produces a Blanc
Fixe equal to the chloride product.
Barium Carbonate
Foraiula, BaCOs; Specific Gravity, 4.2; Synonym, Durex White
This material is practically new as a paint material,
and has only come into use since flat wall paints have
had such a tremendous success in the United States;
and even at that, not very many manufacturers in the
United States use it, although it probably is destined to
become as useful an article as Blanc Fixe.
Bariimi carbonate, under the microscope, has a very
peculiar structure. It is not made by mixing a solution
of barium chloride and sodium carbonate, although that
would be the normal way of making it, but it is made
from bariimi sulphide and sodium carbonate in fairly
133 CHEMISTRY AND TECHNOLOGY OF PAINTS
concentrated solutions, so that the sodium sulphide be-
comes a valuable by-product, and therefore the barium
carbonate can be successfully marketed at a reasonable
price.
In hiding power it is between Blanc Fixe and zinc
oxid, but when used in the proportion of 45 per cent
barium carbonate and 45 per cent of zinc oxid or litho-
pone in a flat wall paint its physical quality makes it
particularly valuable, because the resulting paint with
the proper thinners pro-
j K^ * -• j-^V . duces a velvet finish imap-
^-j 1^^-\ •?'" ' *y* *- preached by anything else.
'""""' ' * Barium carbonate such
; sold for paint manu-
f^''^''!^ \i'y^!'K\*'''^Ki' ^^"^turs must not be con-
founded with Witherite,
the natural form of ba-
% *W>jf"-'''' ji^T* '/y rium carbonate. This is
*"'*^*,fj "I.'.*^.*-; '.^-^^ not found in the United
*, *^*^**i*' States, but is largely
** ' mined in England, Austria
.,^'rv:>-V^4'-^.'^t^ -is
r-^rvV'-'^^^^J^^ ^-tu
ii^.ff :,:>'^yt Vv^T* 'o™<
""'■'^ and Germany. Witherite
has absolutely no paint
qualifications, and is not even as good as barytes.
In composition Witherite is identical with the artificial
barium carbonate, but under the microscope powdered
Witherite is a transparent crystalline material similar in
appearance to table salt.
Silica
Formula, SiOj; Synonym, Infusorial Earth, Silex
The introduction of silex in paint is due to the
researches and investigations made by David E. Breninig,
M.I)., who in the early fifties had noted that when white
THE INERT FILLERS AND EXTENDERS
123
lead was mixed with barytas it stood exposure better
than pure white lead. Late in the fifties he came across
some rock crystal quartz,
and, on grinding and mix-
ing it with white lead,
found that it improved
the paint. The prepara-
tion of silica, especially for
the paint trade, became
an established industry
between 1865 and 1870.
The earher process for
powdering quartz was the
simple and economical
method of dry grinding
by the tumbling process.
The quartz was simply crushed to a granulated state and
then put into a tumbling barrel with pebbles, which was
^ . revolved until the. silica
•^ ''^N^^ was reduced to a compara-
X *». tively impalpable powder.
,^ J- «► ^^ It was found, however,
B v5 '.- \ that this method was not
M ,^' f* * satisfactory', because it did
, f) ' ^ ^ ^ot produce uniform re-
No, 45- Silica, or Silkk — Photomicro-
graph X2SO, ver>- fine grain.
- «» *'
'\^..
V ■ <^■T/^^ ^ ' suits, and the Silex Lead
\^ ii' ff^ "^ Company, which had been
^, ^ , . '^ V J ■ formed for the manufac-
" ' ture of silica or silex for
the paint trade prior to
1870, adopted the process
of heating the quartz to a
visible red heat, plunging it into water, and crushing it after
the sudden change of temperature had split the silica into
No. 46. Silica — Photomicrograph x 2 50,
finely powdered and air floated, uniform
angular giain.
124
CHEMISTRY AND TECHNOLOGY OF PAINTS
a finer state of division. The silica was ground in
tubs under water with stone bottoms and drag stones,
and after it had been thoroughly comminuted it was
washed, floated, dried, and then bolted to a given degree
of fineness. There can be no question that the prepara-
tion of silica in this manner produced a material al great
uniformity, the value of which in paint is unquestioned.
In the early part of the seventies the first practical tests
were made on the coast of Maine. It was found that
pure white lead would not
stand exposure at the sea-
shore for more than a year.
At the end of this time it
resembled whitewash and
presented a poor surface
for repainting. A mixture
was made at that time of
one third silica, prepared by
heating and washing, one
_ third zinc oxid, and one
N0.47. Silica — PhotomicrotcraphXJSO, third whltC lead. ThcSC
verj' fine grain; this material has been materials WerC grOUnd to-
Cround in water. .-i • i- j -i
gether m pure Imseed ou
and Sufficient drier added. At the end of seven years
this paint was still in good condition and presented an
excellent surface for repainting.
Silica, like many of the inert materials, has the added
physical advantage of presenting what is known as a
"tooth," which fits it exceedingly well for repainting.
Silica is inert as an extender or filler in paint, and does
not combine with any other pigment or vehicle. The
detection of silica in mixed paints is very easily accom-
plished by means of the microscope and Nicoll Prism, as
the metallic pigments do not polarize. In chemical
THE INERT FILLERS AND EXTENDERS 125
analysis we often find i per cent of silica in an otherwise
pure paint. This i per cent of silica generally shows
up in large arrow-head crystals scattered throughout
the field of the microscopic vision, and is due to
very small particles of silica which have been worn oflF
from the grinding stones of the mill. The amount of
silica which may be safely added to many colored mixed
paints without detracting from their covering properties,
and which will increase their wearing qualities, is less
than one third of the total pigments used.
The composition of the various silicas on the market
is quite uniform, and those that are made from clear
colorless quartz, or faintly colored quartz, are practically
free from iron. Silica made from rock quartz will assay
99.7 Si02.
Infusorial earth is almost pure silica and is largely
composed of the skeletons of diatoms. It is exceed-
ingly bulky, and is used by some paint manufacturers
to prevent the settling or hardening of paint in cans, and
owing to its light specific gravity it accomplishes this very
well when added in even as small a quantity as lo per
cent.
The question comes up occasionally as to whether
silica will hydrate when heated and thrown into water.
This question must forever be settled by the fact that
analyses of silica treated in such a manner show it to
contain 99 per cent Si02. If any hydration took place
it would be evident in the quantitative analysis. There
can be no doubt that the silicas obtained on the market
which are washed and treated are therefore pure SiOo.
The silicas made from infusorial earth contain a varying
percentage of moisture, but the balance is almost pure
silica.
CHEMISTRY AND TECHNOLOGY OF PAINTS
Infusorial Earth; Kieselguhr; Fut-ler's Earth
Infusorial Earth, Kieselguhr, and Fuller's Earth are
forms of silica which are diatomaceous in nature. Di-
atoms are the - remains of plant life — the silicious
skeletons — the organic matter having been entirely de-
composed, leaving these skeletons. The forms of these
skeletons are wonderful, and a number of Illustrations
will show what they are like. Some are like beautiful
chased jewels or fihgree
work; others are like the
covers of boxes made of
lace work; and still others
are spear-shaped, but all
_^^ of them have the quality
^ti/'Xx ^^"^'^' jfe^SH more or less of absorbing
^^ . ^-^ '-^ ^»aj^^y dyes. They are not pure
^» , «»_ ^ ^gk^r silica, for some of them
^F _-/'*. k. ^ji^ are largely composed of
silica and silicate of alu-
mina or sihcate of mag-
nesia.
These materials are
used both as bases for the lake colors used in making
pigments, and for the purpose of preventing the settling
of certain classes of mixed paint, particularly the first
coats which are not so finely ground. In this respect
these materials are frequently substituted for asbestine,
because they are more or less free from moisture or
water in combination. They can be readily identified
under the microscope on account of their very peculiar
and beautiful forms.
. Infusorial Karth — Photomi-
crogroi>h X150.
TBE INERT FILLERS AND EXTENDERS
137
Clay
Composition, Silicate of Alumina; Synonym, Kaolin, Fuller's Earth
Clay in small quantities is very largely used by paint
manufacturers, first, to prevent settling or hardening
of mixed paints, and sec-
ondly, to produce unctu-
ousness or good brushing
qualit>'. Clay occurs natu-
rally in many paints up to
as high as 80 per cent, as
for instance, ochre, which
is 80 per cent of clay and
20 per cent of coloring
matter. The siennas a!!
contain clay up to as high
as 60 per cent, and as
clay is found naturally in
the pigments referred to
they cannot, of course, be regarded as adulterated, but
when large quantities of
clay are added to other-
wise good paints the wear-
ing quality is reduced, and
therefore more than 10 or
15 per cent is not advis-
able. Clay always contains
a large percentage of water,
and the emulsification that
ensues probably aids in the
non-hardening qualities of
No. so. uiATOMs — Photomicrograph paint. In paste paints of
x6oo, frequently found in whiling. ., ,
the cheaper vanety, par-
ticularly barrel paints, clay becomes a necessity, for these
So. 49. Diatoms — Pholomicrograph
X300, found in whiting, clay, and
infusorial earth.
\
■'■*i,
128 CHEMISTRY ASD TECHKOWGV OF PAINTS
paints are sold at a very low price, and must remain
soft indefinitely and easy to mix.
Kaolin is a type of clay which is used by the pottery
trade; a typical analysis is as follows;'
SiO- 46-27%
AijOj 38.57%
■ Feja.--.- 1.36%
CaO 0.34%
MgO 0.25% .
Na-0 0.37%
HjO 1 3.61 %
It has practically the same physical value as the
ordinary clay, excepting that the pottery clay is usually
whiter in color. Clay has
y^jNf*"^'\^ no hiding power or opacity.
Kaolinite, 2SiOi ■ AliO, ■
2H2O, is the principal con-
stituent of kaolin.
AsiiESTINE AND ASBESTOS
.\sbestine and eisbestos
arc silicates of magnesia,
ihc asbestine having a
short fibre and the asbes-
tos having a long fibre.
Asbestos fibre is used
to a small extent in paint, but it is not as good as
asbestine, because the fibre of asbestos is too long.
However, considerable quantities of asbestos are used
for the making of so-called "fire-proof" paints, and on
this subject it is proper to say that there is no such
' Bull. :,$' (l-''^- Gcol. Sur\'.), Cluys of .Arkansas, p. 21.
i|jh X300.
THE INERT FILLERS AND EXTENDERS i2g
thing at the present time as "fire-proof" paint. It
is perfectly possible to make a fire-resisting paint, but
these paints usually are
of the casein-whiting type. j^ "^"^ . ^W 4
Casein, lime, phosphate of z_.*— *.•. 'J**' »* <«
soda, and whiting, which
when mixed with water
produce fairly good
mine, resist fire for i
while. A typical experiment
has always been to i
small shingle, paint 1
it with a so-called "fire-
proof" paint, and ignite ., ^ ^ „^ .
*^ r J D jjq jj^ Chin-a Clay — rhotomicrograph
the uncoated part; the fire xjoo.
dies out when it reaches the painted part. This can
be done with a piece of wood from ^V to j inch in
thickness, but no timber or board of any size can pos-
sibly be rendered fire-proof
_-^g ;V/^1| [ by paint application, for
%^^*'^t *i.*'.V'-''»*>s when such a piece of wood
M^' • '-** * '-liw^ I J t> ^ or timber is subjected to
*^..i/ * ■ li^^^ ''^E^^ ■ ^"ffi'^i^"* heat, distillation
i'j'TzM^'.'^-i'f^^Sk*^ £« **^ ^^^ uncoated wood on
5-1* u'?'M'''^«3^-5'Jb'i'i^ the inside takes place, gas
^>J^^ ' * ' *!• ^i- « C'-- - '^ generated, and the wood
<il^''.^,fi^v"L/3f*— .■? ' ' bursts into flame. Theonly
'•"'^■itl«,^'.*W'^^' successful method of treat-
■ \ *'^p '*■■ •• * ing wood to prevent it from
* ■ burning is by impregnat-
N-o. 53- CoLL«iD«. Claj— Pholomicrc^ ■ ^^^^^ ^^^ ^^^^ ,
graph xjoo. ° ■'
means of a vacuum pro-
cess; but this is not painting, because the crystallizing
eflfects of the fire-proofing material destroy or peel
4^^
I30 CHEMISTRY AND TECHNOLOGY OF PAINTS
any subsequent paint or varnish, so that up to now
there has been no fire-praof paint made which ren-
ders wood structures fire-
^fj|'#"^. proof.
/ i. ^ , " ,. f^ ■■■ For the painting of
^ iTi r ^#Hw«h '■ ■ 'V shingles where sparks may
' ■■is.' .. ^' ■■" " ' «0 ^\ ' possibly ignite them, oil
f ■Jr^6J-'. ■ /'y, ■ ■■■^Jj>u; « paints containing boracic
-,.■■" , , , v -.d acid and powdered asbes-
gjiv^i/", !JI\ "^ >..' ■i'.*j» tos are used, as a paint
^^ ' y, - . J'''t ->, >/ of this type resists sparks.
^\^' i^fc^^ate^.^. Asbestos can be very
'^^^^_j^5''^ '^ readily identified under the
No. 54. AufcSTist — PhotomicroRraph microscope on account of
^^°°- its long fibre.
The average analysis of asbestine is:
SiOa 62%
MgO 31%
CaO 3%
Water of Crystallization 4%
100%
Calcium Carbonate
Formula, CaCOj
Synonyms: Whiting, Paris While, Chalk, Marble Dust, Artificial
Calcium Carbonate, Spanish While, and White Mineral Primer
Whiting and natural calcium carbonate are prepared
from the natural chalk deposits of the cliffs in the south
of England, and Paris White, Extra Gilder's White, and
Spanish W'hite are all different qualities of whiting, de-
pending on the amount of levigation and fineness of grain.
The mode of preparation is very simple. It consists in
grinding the cliffstone in water, washing it, and allowing
tHE INERT FILLERS AND EXTENDERS 131
it to settle in large vats. The cream, or that which is
nearest the surface, is dried over steam-pipes, bolted, and
sold as Paris White. The
next layers are sold under
the name of Extra Gilder's
White, and the bottom
layer as Commercial White,
of which putty is made. ''V^'*^i^!i:-J?^ v;-^^
Whiting is a neutral calcium jt-*^^* i,»X^« '^••^?^?-''r'•^3ff
carbonate, and with the *iJ*,|\VV^>'a*';"^''i;'^.-r^rt*
exception of the small per- ^V;A^'l*-2;;^'-^iwt%^
■ Photomicrograph
X300. very uniform grain.
centage of water, which is
very variable and depends
upon how thoroughly it has ^°- ss- \\
been dried, it is remark-
ably pure and fine. The material at the bottom of the
tubs known as Commercial Whiting is ne\'er used in
the manufacture of mixed paint, because it is coarse,
contains silica and iron,
and in attempting to grind
this grade the mills are
ruined.
' '» w b ' There is a great difter-
p-T »'*dM&*A** ^"<^^ of opinion as to the
' i^^Jf]li»i^ merits of whiting in paint,
"^^" jlv^? ^"^ '^ ^'^ ^^ conceded
.'.I-*' by every manufacturer
and paint chemist that
the addition of calcium
carbonate in some form
r other is of great benefit
o mixed paint. Some
manufacturers put 5 per cent in all the paint they make,
excepting that which is made according to specification.
No. 56. Gilder's Whttiko — Photomi-
crogi^fh X300.
133 CHEMISTRY AND TECHNOLOGY OF PAINTS
for the excellent reason that any acid which may either
develop in the paint or be a part of the chemioil com-
position of the paint is
slowly neutralized. For
5Jt'5?y4>tfNl^. paints intended for the
-a^'?>"-»?^*'^^>»5^ protection of metal this
n jr. ^^;4"..TV*^iYf**» T^ practice is to be highly
j^;V / * ^i^'^.^L^^** J'ecommended. On the
I other hand, some writers,
who, however, have had
little or no practical ex-
perience, condemn calcium
carbonate in any fonn be-
cause it lacks covering
"'■ "-PL'S™ SZr.^'""'*" -P-i'y o^ Wdtag power.
If a paint were made of
ICO per cent calcium carbonate this statement would
hold true, but where other solid pigments are added
the argument against whiting fails. No particular evi-
dence need be brought to
bear to prove the durability
of whiting, for the reason
that all putty is made of
whiting and oil, and there
are buildings and farm-
houses in any number still
existing where the putty,
after being exposed to the
elements an\nvhere from
twenty-five to sc\'enty-five
years, is, if anything, better N«- sS- Talc (Soapstooe) — Phow-
at the end of that period
than one month after it was applied. Whiting has the
added advantage of being bulky, and priming coats in
THE INERT FILLERS AND EXTENDERS 133
which it is used present a good surface for repainting.
The amount that can be used as an assistant to mixed
paint is very variable, de-
pending largely on the pig-
ments used or shade which
is made. Where a paint
is to be made for the in-
terior of a building in
which acid fumes are gen-
erated whiting should, of
course, be omitted. But
there are so many excel-
lent fillers that the use of
jle one is not always no. 59- rasic jiagnesiuu carbonate
necessary. Whiting as it ^ l'hot<,mict<.Braph xjoo. lixlremely
,^ , . light and fluffy.
IS made today is never
alkaline, for in the drying process it is placed on steam-
pipes and the temperature is so low that decomposition
cannot take place.
r*.^^*mhi^.>^■'■ -. The other forms of cal-
^\i-.\-'/*>^^J^''*^'^ cium carbonate which are
,^ -"*o^*-J*. V* -.V^' '•^"'' - ^^ "^^ ^""^ produced by
y ;J'i '^1 •* •'.'■V '^'^•''"l grinding white marble very
"-^"t/ "..'*" f'\Vt':.N*V?'.,''\(%' fine, and, generally speak-
>vCjt>;_»:^'-t"t.j,*.--V(.'^' V^-i ing, these varieties are
'^\'^i^;u->'; X*.\v-,tLf. '*j better for mixed paint pur-
* •» V. ^i^'^^X.* > ff JV'^' poses than the whiting
^•^''i-i'^^^^'^V^* made from chalk. In the
^y^t*^^\ /-- ' first place, the ground
X(i. 60. Aluuisa Hydr.\te, used as a marble or Hmestone con-
base for printing ink colors— Photo- tains Httle or no moisture;
micrograph xjoo. • ^l j i .l
m the second place, they
are ground exceedingly fine, and being angular or crys-
talline in shape they form a better surface, if anything.
134 CHEMISTRY AND TECHNOLOGY OF PAINTS
for repainting than whiting; and third, where an absolute
chemical composition is wanted they produce more uni-
form chemical compounds. Whiting and white filler
compounds bulk between 3f and 4I gallons per hundred
pounds of dry unit.
There is another grade of calcium carbonate which
occasionally appears on the market and is a by-product,
principally from soap works. It has all the physical
characteristics of a good article, but its chemical char-
acteristics condemn it at once as a paint material on
account of the free lime which it contains. It is worth-
less for the purpose of making putty and useless as a
paint filler. When putty is made of it, it forms a lime
soap and gelatinizes the contents of the packages.
White Mineral Primer
This is a white crystalUne limestone which is found
chiefly west of the Mississippi, and more largely used by
western paint manufacturers than by eastern, for the
freight is against its shipment to eastern points.
In physical structure it is similar to barytes, but of
much lighter gravity and greater bulk. For instance,
100 pounds of white mineral primer will yield 4.6 gallons,
while 100 pounds of barytes will yield 2I gallons. White
mineral primer has very little opacity or hiding power,
but it has the physical quality of "tooth," and when
mixed with zinc or sublimed lead it is superior to any
other form of whiting, wdth perhaps the exception of the
artificial calcium carbonate. In many respects it is similar
to finely powdered marble dust.
Marble Dust
Considerable marble dust is used in certain forms of
paint, marble dust being chiefly composed of calcium
THE INERT FILLERS AND EXTENDERS 135
and magnesium carbonate with i or 2 per cent of
ferric oxid. It is a brilliant white, and when passed
through a screen of 200 mesh is similar to white mineral
primer. Its chief use is for carriage and coach paints
and also as a primer for wood generally, because it pre-
vents peeling on account of its structure, having the
same properties of "tooth" which are ascribed to silica
and white mineral primer.
Spanish White
Spanish White is similar in all respects to powdered
chalk, Paris White, or whiting, and at the present time
is a name only, for there is little or no whiting for paint
purposes that is now imported from Spain, all of it being
of the cliffstone variety from England.
Artificial Calcium Carbonate
This material has already been referred to. It has
very excellent properties, but usually has the one great
defect, viz. the small percentage of free alkali both
of lime and soda which it contains, and this produces
"livering" of paints. Wherever it can be obtained in
neutral form it is excellent when added in small quan-
tities to many priming paints.
Gypsum
Formula, CaS04+ 2H2O
As an inert pigment or filler gypsum is very largely
used in the United States. It is found in twelve states
and in very large quantities in Canada. Its specific
gra\'ity is 2.5 and its formula as cited above is CaS04
plus 2H2O. This formula represents the gypsum of
commerce, as sold to the paint trade, so closely that the
136 CHEMISTRY AND TECHNOLOGY Of PAINTS
percentage of water in several samples averaged over 19,
whereas the theoretical is 2Q.2.
No. 61. AUERICAN Gvpsuu — Photo- No. 6», AuEKiCAN GvpsuH — Photo-
micrograph X150, fairly uniform nucragraph X300, tian^uicnt flat
and flat crystals. crystals.
There is a great difference of opinion as to the merits
of gypsum as a paint filler, for it must be borne in mind
No. 6j. .VuERiCAN Terra .'Vlba — Pho- No. 64. Calciuu Sulphate (Gypsum)
lomicrograph 150, very finely pow- — Photomicrograph X«50 {.\meri-
<i.Tcd. can).
that if it contains any free lime, or if it is not fully
hydrated, the lime will act injuriously on the paint and
THE INERT FILLERS AND EXTENDERS 137
thicken it unduly. The defect produced by its incom-
plete hydration will be to take up moisture from other
•JL^.
<4..
i^
No. 65. Frexch Terra Alba.— Pho- No. 66. TtRBA Alba (French Gypsum) —
tomicroKraph xaso, composition Photomicrograph x6oo, showing co'S-
CaSOt + a HjO, same as g>psiiin. talllne structure of calcium sulphate.
materials in the paint so that a hardening or setting
process goes slowly on.
No. 67. Calcium Sulphate — Photo- No. 68. Precipitated Calciuu Sul-
micrograph X300. Ppted, from cold, pbate — Photomicrograph y.joo. Note
moderately concentrated solutions. the long- fibred crystalline structure.
Some of the gypsum sold in the east is made from
alabaster, this being a native, translucent calcium sul-
138 CHEMISTRY AND TECHNOLOGY OF PAINTS
phate. The Pennsylvania Railroad in its freight car
color permits the use of 70 per cent of gypsum, and as
good results have been obtained by this company in the
use of calcium sulphate as a filler the condemnation of
this material is without much foundation. Due con-
sideration must be given to the fact that thousands of
tons of Venetian red are consumed by the paint industry
every year, and that the composition of Venetian red
wall average from 15 to 40 per cent ferric oxid, the
balance being entirely gypsum. It is nevertheless true
that as one part of gypsum is soluble in five hundred
parts of water, excessive rainfall will erode it in a paint,
particularly where the binder is easily attacked.
Where calcium chloride is a by-product large quan-
tities of calcium sulphate are artificially made, and many
paint manufacturers prefer the artificial calcium sul-
phate to the natural. The photomicrograph shows this
to have a long^fibred crystalline structure, and while
it has no chemical properties which are different from
the natural gypsum, its purity and physical structure
make it valuable for many mixed paint purposes.
THE INERT FILLERS AND EXTENDERS
139
Composition of Various Samples of Gypsum
CALCIUM
SUXPHATE
WATER
7745
20.14
77.79
21.39
78.44
20.76
77.46
20.46
79.30
48.84
64.63
18.75
67.91
17.72
71.70
18.68
59.46
16.59
69.92
18.85
69.26
21.50
64.22
14.00
76.02
19.00
77.76
20.28
76.44
20.02
78.60
20.31
PERCENTAGE
OF GYPSUM
94.09
97.59
99.18
99.20
97.92
98.14
85.63
90.38
76.05
88.77
90.76
78.22
88.80
72.60
95.02
98.04
94.84
96.46
98.91
AUTHORITY
Conn. Exper. Station
Orton, Ohio Survey
David T. Day
G. E. Patrick
E. H. S. Bailey
E. H. S. Bailey
E. H. S. Bailev
E. H. S. Bailey
Okarche Cement Co.
E. H. S. Bailey
Paul Wilkinson
U. S. Geo. Sun'ey
Wilbur G. Knight
Calif. Exper. Station
Calif. Exper. Station
G. P. Grimslev
G. P. Grimslev
Conn. Exper. Station
Conn. Exper. Station
G. P. Grimsley
CHAPTER XI
Mixed Paints
We have seen from the foregoing chapters the ma-
chinery necessary for the manufacture of mixed paints
and the raw materials most generally used.
Of all the shades of mixed paints made, the white
paints are the weakest and perish the most quickly, and
the black paints, particularly those high in carbon and
the ferric oxids, are those which last the longest. It is,
for instance, impossible to state which of the white paints
is the best, and individual opinions or single instances
are not permissible for comparison. A test of white
lead at the seashore will show that white lead is not
as good as other white pigments, and at the same time,
in a test in the interior of the country, or where climatic
changes are not generally marked, white lead will show
up wonderfully well. As an instance of this, it may be
cited that the United States Light House Department
ordered their white mixed paint to be composed of 75
per cent zinc oxid and 25 per cent white lead, for at the
seashore this mixture is better than either pigment alone.
A series of experiments conducted by the author
showed that white lead perishes through the action of
carbon dioxid in rain water. As soon as a film of oil
becomes vulnerable the white lead becomes soluble in
the rain water, the so-called chalking being traceable
to this cause. Zinc oxid is also attacked by carbon
dioxid, but not nearly as quickly as white lead. Sub-
limed white lead is attacked still less than zinc oxid and
140
MIXED PAINTS
141
zinc lead. The western zincs and leaded zincs, which
vary in their proportion of lead sulphate, are slightly
more permanent than zinc oxid, but the moment an inert
filler such as barium sulphate, either precipitated or
natural, silica or magnesium silicate, are added to the
white lead and zinc oxid paints, their resistance to atmos-
pheric influence is largely increased. Therefore these inert
materials are an improvement to paint, and where no
specification is to be followed they cannot be regarded
as adulterants. The principal reason why these inert
fillers are not added in greater quantities to white paints
is due to the fact that the consuming public is not yet
sufficiently educated to the use of such materials.
Lithopone has proved itself an extremely valuable pig-
ment, particularly for floor paints and for marine
paints where shades other than white are demanded.
In no sense can the 70 per cent of barium sulphate
which is contained in lithopone be regarded as an adul-
terant, because it is a constituent of the paint itself.
The carbon and graphite paints have wonderful
powers of resistance, provided they are properly diluted
with a heavier pigment so that the film is thicker.
The average graphite paint will cover one thousand square
feet to the gallon, but the film produced is so thin that
when it once starts to go, either through the abrasive
influence of the solid contents of the atmosphere or the
decomposing action of water, the surface is soon exposed;
but when many successive coats are applied to produce a
sufficient thickness far better results are obtained.
The ferric oxid paints strike a happy medium, for
they cover from four to six hundred square feet to the
gallon ; but their color is limited to three shades — red,
brown, and black. As priming and second coats they
are, however, ideal, and as finishing coats where
142 CHEMISTRY AND TECHNOLOGY OF PAINTS
these shades are admissible they serve their purpose
exceedingly well.
No single pigment is as good as a mixture of pigments,
and the intelligent combination of the raw materials
always produces the best results.
There is continued rivalry between the manufacturers
of the lead pigments and the manufacturers of the zinc
pigments, both of whom claim superiority for - their
particular pigments. If you read the advertisements in
any of the weekly journals or in the paint magazines
you will see after reading one advertisement that only
white lead is the best pigment, and after reading another
advertisement that only zinc oxid is the best pigment;
but competent investigators who are more or less honest
hesitate to say that zinc oxid is better than lead, or
that white lead is better than any other pigment. As a
matter of fact, it is a very difficult thing to decide;
a just decision would be that they are all excellent.
White lead, of course, stands supreme for hiding power.
There is no pigment with the exception of lithopone that
will show as much opacity as a single coat of white lead.
On the other hand, there is no material that has such
wonderful qualifications for enamel-making as zinc oxid,
and, as a matter of fact, the only single pigment that can
be used and is used for certain purposes is zinc oxid, all
the others being unsuited for the manufacture of prepared
paints on account of their gravity. It has been con-
tended that white lead alone mixed with the proper oil
and driers has stood for many years, and this is quite
true; but zinc oxid alone, as a pigment at the seashore,
does not give as good results as white lead, because zinc
oxid dries too hard; and yet, from the large experiments
made by the author, a mixture of the two is unques-
tionably better than, any single pigment, although
MIXED PAINTS
143
failures of mixtures are perhaps as frequent as failures of
single pigments.
That mixed paints have become a necessity is evi-
denced by the fact that considerably more than one
hundred million gallons have been made in the United
States since 1907. The exact amount made at the pres-
ent time is very difficult to determine, but it has been
estimated as being over one hundred fifty million gallons.
At the same time, the production of lead has increased,
and the production of zinc pigments likewise. Likewise,
the production of both the sublimed white lead and of
the sublimed zinc and lead of the Ozark type are increas-
ing, and have come to stay, so that the criticisms of the
various pigments are more or less a question of com-
mercial rivalry rather than an inherent defect in any
of the pigments. They all serve an excellent purpose
and all are exceedingly useful.
Many manufacturers of mixed paints guarantee that
their paints will stand five years under ordinary con-
ditions in the United States. This guaranty is prob-
ably excessive, for there are many details which on>
their face appear insignificant and are not taken into
account by a manufacturer.
The priming of wood has much to do with the life
of paint, and a paint that contains much oil or vehicle
to which either pine oil or benzol has been added,
so that penetration into the wood can be effected, will
give much better results than very heavy paints con-
taining only 40 per cent of vehicle and 60 per cent of
solids. For the priming of wood this proportion should
be reversed and the paint should contain at least 60
per cent of liquids and 40 per cent of solids, to which for
raw new surfaces a penetrative solvent like benzol, toluol,
or pine oil should be added.
\
144 CHEMISTRY AND TECHNOLOGY OF PAINTS
On the other hand, the oxid of iron paints such as
Princess Mineral or Prince's Metallic have been known to
last twenty years on wooden barns in the country dis-
tricts; this is undoubtedly due to the fact that a reduced
oxid of iron of the Prince's Metallic type is not affected
by gases, nor does it react on linoxyn. As cottages,
villas, and private residences are never painted a dark
brown or a deep red like any one of the ferric oxic com-
binations, it is therefore proper that this discussion relate
entirely to the lead and zinc pigments which are most
largely used for the purposes mentioned.
Anti-fouling and Ship's Bottom Paints
Anti-fouling and ship's bottom paints are always
sold ready for use, and there are two distinct types, —
the copper paints and the mercury paints.
There is a continual difference of opinion among both
consumers and manufacturers as to whether the anti-
fouling type of paint should be one that does not dry and
be of the exfoliating tjpe, which means that it contains
lard or tallow and that when the barnacle or seaweed
attaches itself it drops off by its own weight, or whether
the paint should be of the poisonous type, so that when
the barnacle or submerged growth has absorbed a suf-
ficient quantity of the poison it dies and drops off.
This is a much mooted question, and there is much to
be said on both sides. Naval Constructor Henry Wil-
liams of the United States Navy has probably done more
work on this subject for the American Navy than anyone
else, and his tvqie of paint which contains the red oxid
of mercury has undoubtedly given far better results than
any other anti-fouling paint. The composition of the
paint used by the United States Na\y is as follows:
MIXED
) PAINTS
U. S. X.
Anti-Fouling Paint
6i gals. Shellac Varn.
15 lbs. Zinc Oxid
4 '' Den. Ale.
5 " Blanc Fixe
2\ " Pine Tar
25 " Indian Red
2\ " Turps.
10 " Red Oxid Mercury
Yield :
15 gals.
145
The copper paints which are found on the market con-
tain from 10 percent copper scale (copper oxid — CuaO)
to as high as 40 per cent. As a rule, this is added in a
ver>' fine powder to a mixture of linseed oil, pine tar,
benzol or gas house liquor, and oxid of iron in some form,
usually of the Prince's Metallic type, is added as a
pigment for hiding power. This is a so-called red or
brown copper paint. The green anti-fouling is generally
a copper soap manufactured by saponifying either linseed
oil, tallow or fish oil with caustic soda, and then adding
sulphate of copper to this soap, which produces an oleate
or linoleate of copper and sulphate of soda as a by-product.
The sulphate of soda is washed out, the remaining water
boiled off, and then pine tar and linseed oil added to the
mixture together with chrome yellow and Prussian blue
for hiding power. This yields a semi-drying or non-
drying type of green anti-fouling, which in many instances
has given excellent results, but which in some tropical
waters does not show up as well as the oxid of copper
paint. The copper paints do not show up as well as the
mercury paints.
There is a third ty^^e which is not a paint, but which
is really a soap that is applied hot. Oleate or linoleate
of copper mixed with China wood oil when melted and
applied to a thickness of about iV to \ of an inch has
given very good results, and it is stated that this tjpe
of copper paint is a happy medium and possesses both the
exfoliating and the poisonous qualities so much in demand.
146 chemistry and technology of paints
Concrete or Portland Cement Paints
Portland cement is an alkaline rock-like substance,
which after it has set liberates lime. The literature is
replete with statements that Portland cement floors
cannot be painted, and it was not until 1903 that the
first successful experiments were made for the painting
of Portland cement. Prior to that time all sorts of
things were recommended, such as strong acids like
sulphuric acid and acetic acid, but it was soon found
that the application of acids of this type to Portland
cement destroyed the Portland cement because it dis-
solved out the lime and left the sand and aggcegite
loosely bound.
Portland cement floors "dust" up under the abrasion
of the heel, and until a successful method for painting
them was found it was impossible to use them in an
unco\'ered condition. In power houses where delicate
electrical machinery was placed the contact points were
ground out by the siHcious matter floating in the air
through abrasion of concrete under the feet. The ac-
companying photomicrographs show the appearance of
a Portland cement floor highly magnified, and indicate
in a general way the necessity for painting Portland
cement. In warehouses, storerooms and office^ ^lerally,
concrete floors had to be covered with liiKiici
to prevent this continual dusting, which became 00
The paints made of drying oils were readily
and gave unsightly effects, and it was not until- J
l)u!)licali<)n of a patent on this subject (U. S. IicU
Patent \o. 813,841) that the trade in genera! began^
understand that a resin acid was necessary to combine »
the lime and not destroy It. Previous attempts ha* \
been made de])ending upon the destruction of the lime,
iflXED PAINTS 147
but in this patent it was first shown that a chemical
reaction took place and the lime instead of being de-
stroyed was made to serve a useful purpose. A resinate
of lime was formed when the coating applied had a
sufficient acid number.
The amount of free lime in concrete is not very
great, for in a i : 3 mixture, that is, a mixture containing
one part of cement and three parts of sand, the top sur-
face varies in composition from 0.87 to 1,6 per cent of
free lime. A large number
of analyses were made by
the author, and it became
obvious that an acid num-
ber of 5.0 is sufficient to
more than neutralize the
amoimt of lime present,
and once neutralized dust-
ing does not take place.
It is well known that con-
crete of any kind and of
any mixture is rapidly
disintegrated by paraffin
or machinery oils and re-
duced in time. If, how-
ever, the cement filler or
neutralizing liquid is composed of China wood oil and
a haM resin like copal, the resulting calcium resinate
becoims insoluble in oil, so that oil dripping on a
«r of this kind does not disintegrate the Portland
lent. Oil collecting on an unpainted concrete floor
cause the floor to become as soft as cheese in time,
I and then there ispo remedy for it excepting to take up the
floor aA put-AJKA a new one. 'Hhere is no record that
China vwd oil a^fcopal had ever been used on Portland
No. 69. Photomicrograph of Portland
cement floor composeti of 2 parts sand
and I part cement. This Hoor is po-
rous and will disintegrate rapidly unless
properly treated with a cement floor
148
CBEMISTRY AND TBCBN0U3GT OF PAINTS
cement floors prior to the apf^cation in question, and
that this patent was new and useful is demonstrated by
the fact that there are practically at this writing over
forty Portland cement paints on Uie market, all o£ them
based on the same theory.
In 1910 it was suggested that zinc sulphate be used to
overcome the pernicious action of the free lime in Port-
land cement, and for a time this material had quite a
vogue, but it has turned out that no man could tell how
much zinc sulphate to use, for no man knew definitely the
amount of free lime in any
large area of Portland ce-
ment, and therefore either
too much or too little was
used. If too little was used
there was still some free
lime left; if too much was
used sulphate of zinc crys-
tallized out, and when the
wall or floor became wet,
either through rain or
through washing, the film
of paint peeled off.
Practically all the paints
for Portland cement that
arc on the market contain either China wood oil or a
copal resin or both. Those composed of both of these
materials have given the best satisfaction. Where ten
years ago there was only one of these paints on the
market today there are a large number, and it is
estimated that more than a million gallons per year
at this writing are used for the surface protection of
Portland cement.
Ko. 70. Highly magnified view of a
fine crack in Portland cement con-
struction — an example of incipient
disintegration.
mixed paints 149
Paint Containing Portland Cement
There is only one paint in existence thus far that
contains a material equal to Portland cement, which
is a tricalcium silicate and dicalcium aluminate, and
which on setting liberates lime. This paint is known as
"Tockolith," and it has been and still is very largely
used among engineers for the protection of steel against
corrosion.
The author cannot go into this subject any more
deeply because this discovery is his and he is interested
in the manufacture of this material, and furthermore,
this book is not the place to exploit a proprietary article;
but inasmuch as this paint has been regarded by many
engineers as at least a step toward the solution of ,the
question of the protection of iron and steel, it is fitting
that this brief mention of the material should be made.
Damp-Resisting Paints
Paints of this character are comparatively new, the
first one having been manufactured by the author's firm
and put on the market in 1892. It was made for the
purpose of coating brine pipes and pieces of machinery
which were continually under water. The original paints
of this character were produced by melting a good grade
of asphaltum and adding a suflScient quantity of gutta-
percha together with a suitable solvent and a small per-
centage of pigment. These paints served their purpose
very well and were used very largely, but no matter how
carefully compounded the gutta-percha separated from
the asphalt base if the paints were allowed to stand for
any length of time.
I50 CHEMISTRY AND TECHNOLOGY OF PAINTS
Further experiments showed that cement mortar
would adhere most firmly to such a paint. The paint
could be applied even to a new brick wall, lathing
and furring being omitted. It took such a long time,
however, to introduce a paint of this character to the
building public that the author's firm never thought it
worth while to patent the application.
Damp-resisting waterproof paints are now an adopted
fixture in the paint industry, and while bitumen forms
the base of paints of this character, treated China wood
oil, and treated linseed oil in which glycerine is replaced
with a suitable metallic base, should be added when
making these paints. They are used widely and in
various ways, having served their purpose so weU that
engineers are beginning to adopt such paints as priming
coats for metallic structures wherever cement or cement
mortar is to be applied, so that oxidation by electrolytic
action may be prevented.
Enamel Paints
Enamel paints in former years were pigments ground
in varnish, which dried with a high gloss. Some people
objected to this high gloss, and where a good grade of
xarnish was used the film was rubbed with pumice stone
and water until it produced an egg-shell finish. This
then led to semi-gloss enamel paints, and finally we have
the misnomer of having perfectly flat enamel paints
today, for the very word ^* enamel" indicates gloss.
For decorati\'e use the j^rincipal enamel paints are
white, but it must l)e said at the outset of the chapter
that this subject cannot be thoroughly treated in this
book. It has become so vast that it would take a book
of this size alone to do the subject justice. There are
MIXED PAINTS 1 51
\^st quantities of enamel paints made which are colored,
but these are principally used for machinery of all kinds,
for automobiles and for the so-called enamelling of various
utensils, such as tool handles and the like. There are
also vast quantities of black enamels made for technical
purposes, and these are used for the manufacture of oil-
cloth, patent leather and mechanical appliances. Those
for oilcloth and patent leather are true oil enamels;
those for mechanical appliances are principally made on
an asphalt base. This chapter will treat of the subject
of enamel paints for decorative purposes, which are
principally white and mainly based on zinc oxid ground
in a varnish or varnish oil.
Prior to the mixed paint era white enamel was made
by taking zinc oxid ground in either poppy oil or a
bleached linseed oil, and thinning it with damar varnish
as it was needed, and the painter did this himself. But
as ready for use enamels were demanded improve-
ments were made on this type of material. Today
the three types of white enamels are:
First. The zinc oxid types ground in damar varnish.
Second. The lithopone types ground in China wood
oil and rosin varnishes.
Third. The zinc oxid types ground in stand oil only.^
The damar tj^je first mentioned is simple to make, but
produces an enamel which does not flow out, which sets
very quickly and which sometimes settles hard in the
package and sometimes does not, depending entirely upon
the gum damar used for the purpose. There are a great
many varieties of gum damar whose acid figure ranges
from 8. to 26., but the acid of gum damar is very weak
as compared to the acid of the majority of copals, and
* Stand oil has been described on page 176 in the chapter on
Linseed Oil.
152 CHEMISTRY AND TECHNOLOGY OF PAINTS
does not readily unite with a base like zinc; therefore
a damar type enamel remains in suspension for several
years. For enamel purposes damar varnish is usually cut
cold, that is to say, six pounds are dissolved in a gallon
of solvent in an ordinary vessel at room temperature;
the resulting varnish is always cloudy, due to occluded
water in the damar. To remove the latter the cold-cut
damar is placed in a steam-jacketed kettle and heated to
about 220° with steam under pressure. Steam at atmos-
pheric pressure has a temperature of 212*^ F., so that at
least ten pounds pressure is necessary in a steam-jacketed
kettle to drive oflF the moisture contained in damar; but
when this is done the damar darkens unless the operation
is carried out in an aluminum or silver-plated kettle.
Such solvents like cymene, toluol and xylol are added
up to 5 per cent to damar varnish to overcome the
cloudiness with fairly good results, but the action is not
immediate, and the damar must be tanked for a con-
siderable time.
The second type, or lithopone and China wood oil-
rosin varnishes, are very good for household use, but not
so good for painting furniture, unless the varnish is
made by an expert varnish maker with a minimum amount
of rosin and the maximum amount of China wood oil,
otherwise varnish of this type becomes hygroscopic in
damp weather or sticky in hot weather. White pigments
other than lithopone are not recommended for enamels
of this t}Tpe because of the high acid figure of the varnish.
The third type, in which stand oil or linseed oil and
zinc oxid are used alone, is the popular type of today,
but has the disadvantage of drying slowly, yet this type
of enamel will last for many years, and stands exposure
even in the American climate for about eighteen months.
It is made as follows:
MIXED PAINTS 153
Ten pounds of zinc oxid are ground in ordinary raw
linseed oil, and this paste after having been finely ground
two or three times is mixed with one gallon of stand oil,
and then a gallon or less of turpentine or a mixture of
turpentine and turpentine substitute is added. When
made in this manner it takes iio*^ F. of heat four or five
hours to dry it so that it is free from tack.
Another method is to grind ten pounds of zinc oxid in
japan drier, which may be a drier made of resinate of
manganese and lead, and then add ten pounds of this
paste to one gallon of stand oil. This will air-dry in five
hours, and while it gives good results for interior pur-
poses it is not recommended for exterior use.
A third method of making these enamels is to grind
the zinc oxid together with the stand oil in a roller mill,
and then reduce with the necessary quantity of diluent
and drier and strain very carefully.
All enamels made along these lines have a tendency
to turn yellow in the dark. Some, in fact, turn exceed-
ingly yellow — almost the color of beeswax — depending
upon the amount of chlorophyll or green coloring matter
in the original linseed oil, and no method has yet been
devised whereby this can be prevented. Many experi-
ments have been made by the author tending toward
improving this with partially good results, such as, for
instance, the addition of an oxidizing material like
hypochlorite of lime to the enamel.
From the foregoing it is clearly evident that enamel
paints may be nothing more or less than pigments ground
in boiled linseed oil without the addition of any resin or
gum, and the effect produced is that of high gloss and
flexibility.
i
CHEMtSTRV AXD TEC/INOLOCV OF PAINTS
Flat Wall Paints
Flat wall paints have come into existence ia.
United States, and it is estimated that hundreds of %
sands of gallons are now made yearly, and that
give excellent results. Most flat wall paints c(^
lithopone as a pigment, the photogenic quality of ij
does not play a great r61e in interior painting. H
of the flat wall paints contain as high as 20 per cdl
water in the form of an emulsion, as is the case when
water is admissible in mixed paints; for in England
flat wall paints which are sold under a different
either in paste form or ready for use, are all white
containing a small percentage of Unseed oil, and are
reverse practicaUy of the American tj^pe of paints. 1
are called washable in England when they are wsj
from the bottom up, for when they are washed froq
top down and the water streaks the wall there is dd
of dissolving some of the paint and producing a bad
whereas the American types of wall paints, even
that contain 20 per cent of water, withstand the
of washing either from the top down or from the
up. There are, of course, many types which
no water, the principal vehicle for this tj-pe of
being a semi-fossfl damar mixed with linseed oil or J
generally a rosin-China wood oil varnish containing^
50 per cent of solvent. *
Many of the failures of the flat wall pamts 4
peel and disintegrate are due to the sizing on which
are painted. Glue, shellac or cheap varnish sizing
generally worthless on plastered walls, while an oil)^
acid X-Ypc of filler gives results which are permanea
mixed paints 155
Floor Paints
Wooden floors are painted as a rule with a varnish
paint which dries hard over night and produces a wear-
resisting waterproof surface. In composition, paints for
wooden floors are analogous to paints for concrete floors,
and are composed of a minimum amount of oil which
dries by oxidation and a maximum amount of hard resin
varnish. The rosin varnishes, particularly those of the
China wood oil type, do not wear as well as the hard
resin varnishes.
The pigments used in floor paints do not play a great
role. Numerous experiments made show, for instance,
that zinc oxid is not a useful pigment for the reason that
the acid number of a floor paint varnish is sufficiently
high to combine with the zinc and form an unstable paint
— one which thickens up in the container and becomes
unfit for use in a few months. Therefore lithopone is
found very useful, and the inert pigments are preferred
also for this reason.
Shingle Stain and Shingle Paint
Shingle stain is not to be confounded with shingle
paint. A stain for shingles is translucent; a paint for
shingles is opaque, and the difference between the two
is quite marked. One shows the grain of the wood, and
the other gives a painted effect and does not show thfe
grain. There is hardly any difference between shingle
paint and the average ordinary mixed paint, with the
exception that some manufacturers add asbestine in
order to give it some fire-resisting quality. On this point
it is well to mention that shingles that are painted, par-
ticularly with a paint that has a fire-resisting quality,
156 CHEMISTRY AND TECHNOLOGY OF PAINTS
are superior to those coated with shingle stain, even
though they may not look as artistic, because sparks
flying from a chimney on a roof that has been stained
and has thoroughly dried out are very likely to ignite
the roof.
Shingle stain is generally made from the very brilliant
pigments and crude creosote. These pigments are as a
rule ground in linseed oil, and two pounds are generally
added to a gallon of creosote. Ordinary creosote oil is
used for this purpose, probably because it has some wood
preservative quality. Other manufacturers use ordinary
kerosene and take two pounds of the strongest colors in
oil that they can get. Still other manufacturers use
crude carbolic acid or crude cresol and kerosene, but
in spite of all these treatments shingles rot just the same.
It is the soft pastel effect which a shingle stain gives that
commends it so highly; but the same pastel effect is
produced with shingle paint after the lapse of a year
or two, provided a good paint is properly reduced with
about 50 per cent of volatile solvent.
On new work shingles are generally dipped. A bundle
is taken and dipped into a barrel and allowed to soak
so that the wood will absorb all that it can. On old
work, of course, it must be applied with a brush.
Asbestine is frequently added in the proportion of
one pound to the gallon of shingle stain containing heavy
colors to prevent them from settling. One of the most
difficult shingle stains or shingle paints to produce is a
permanent red. For this purpose the oxids of iron
(FcoOs) are used, but wherever oxid of iron is exposed to
the sunlight in the presence of linseed oil or other organic
oils it probably changes to a ferroso-ferric condition,
becomes considerably darker and is converted into a
brown. This is less noticeable in a shingle stain than it
MIXED PAINTS 157
is in a shingle paint, because the shingle stain is largely
composed of a volatile solvent, and the small amount of
binder has relatively a lesser action than the binder in
the shingle paint. It has been suggested, and there is
probably some value to the suggestion, that potassium
dichromate to the extent of one ounce to the gallon
should be ground in crystalline form with the paint
in order to prevent any reduction. Hypochlorite of
lime has also been suggested, and of the two the
hj-pochlorite would be the better as long as it would last,
because it would not wash out and be likely to stain the
building. Dichromate would be very likely if it ran over
the gutters or leaders to produce a bad stain.
CHAPTER XII
Linseed Oil
This oil is still the principal oil used in the manu-
facture of paints, and mthin the last ten years ver>^
extensive work has been done on the constants and
specifications for linseed oils generally, as will be noted
from the reports of the American Society for Testing
Materials and several other reports quoted by the author.
The raw linseed oil produced in the United States
comes principally from the northwest. The foreign oils
come from Calcutta, the Baltic, and the Argentine
regions. There is considerable difference between these
oils, the Baltic being perhaps the best and very highly
prized by varnish makers.
The constants of linseed oil show very wide variations;
for instance, its specific gravity will run from 0.931 to
0.935. Its iodine value will var>' from 160 to 195 or
more, while the saponification value will run between
190 and 196. The greatest differences are found in
North American linseed oil, the figures being sometimes
so perplexing that it is difficult to reconcile them wath
the standards of Baltic oil. These discrepancies are
easily traceable to the natural impurities found in Ameri-
can linseed oil, as, for instance, oils from weeds growing
in the flax fields. American linseed oil is likewise
inclined to show the presence of water to a greater
extent than fore'gn oils, but this, however, is a question
of age. If raw linseed oil is allowed to settle until it
becomes perfectly clear and shows no sediment or tur-
LINSEED OIL 159
bidity at 0° C, it cannot be said to contain water.
The question here naturally arises as to the use of the
term "pure." Calcutta and the Baltic seed are freer
from foreign seeds than the American product, and
although the amount of foreign seeds which appear as
weeds in the field is very small, their presence alters the
chemical and physical characteristics of the American
oil. Taking Baltic as a standard, it could be reasonably
argued that American linseed oil is adulterated, yet no
man would have a moral or legal right to condemn
American linseed oil because it differed from the Baltic.
On the other hand both climate and soil have a well-
knowTi influence on vegetation; even the percentage
of oil derived from a given seed cannot be said to be
constant. It is also stated that virgin soil produces
better seed than a replanted field and this statement
appears reasonable.
To how great an extent the natural or negligible
admixture of the oil from foreign seeds to linseed oil
affects the wearing quality of the oil, it is impossible to
say, but it must be admitted that an oil containing up
to 3 or 4 per cent of the oil of foreign seeds or weeds
will not act as well in the kettle for varnish or boiling
purposes as a purer oil. Taking these facts into con-
sideration, a chemist must beware of giving an opinion
as to the quality of linseed oil, and where there ;s no
evidence either chemical or otherwise that the oil has
been intentionally diluted with other materials no
adverse opinion should be forthcoming. If the exam-
ination of linseed oil shows an appreciable percentage
of paraflSn oil, it can be positively inferred that no
weed growth had anything to do with this adulterant
and the mixture must be regarded as intentional or
accidental.
i6o CHEMISTRY AND TECHNOLOGY OF PAINTS
Raw linseed oil is extracted from the seed by the
old-fashioned method of grinding the seed, heating it,
placing it between plates and then pressing it until the
remaining cake contains the least possible quantity of
oil. The newer method is a continuous process by which
the seed is ground and forced in screw fashion through a
tube, the oil oozing slowly through an opening in the
bottom of the tube and the cake falling out at the end
in flakes. When the seed is fed in this manner without
heating, a better quality of oil results. The third
method consists in crushing the seed and extracting the
oil by means of naphtha. The resulting liquid is evapo-
rated, the naphtha recovered and the oil sold for painting
purposes. It appeared, however, that this process, while
very profitable for the manufacturer, was not profit-
able for the consumer, and although it made a veiy
fair paint oil, it was found that for the purpose of coating
leather, oilcloth, and window shades, the oil had the
unfortunate faculty of soaking through the fabric, and
when a piece of goods was rolled up too soon and
allowed to stand for the greater part of the year it
was almost impossible at the end of that time to unroll
the goods, the whole having become a solid mass. Inves-
tigation showed that some of the proteids in soluble
form were extracted by the naphtha. This was called
''new process oil,'' and it was generally understood that
cake made from new process oil was not as good cattle
feed as cake made in the old-fashioned way, probably on
account of the removal of part of the proteids.
If linseed oil were uniform, both as to source and
nature of seed, a chemical formula could be established
for it, but because it is not uniform the acids cannot
be given in quantitative relation. Linseed oil should
give no test for nitrogen; if it does, the proteids in the
LINSEED OIL i6l
seeds have been attacked. Probably 95 per cent of all
the linseed oil made is sold in the raw state, and, strange
to say, probably 95 per cent or over of all the linseed
oil used is consumed in any other but the raw state. It
must not be inferred that all paint manufacturers
manipulate or treat their linseed oil by heat and other
methods of oxidation, for, while many of them claim to
do so, not one that the author is acquainted with could
afford to handle and manipulate linseed oil. At the same
time, raw linseed oil cannot be used for the purpose of
making paints unless a drier be added, and from the
very moment that the drier, either in the nature of a
siccative oil, resin, or Japan, is mixed with the oil, the
chemical constants of the oil are altered. The change is
an irreversible reaction. As an example, it may be cited
that if 90 per cent of linseed oil be mixed with 10 per
cent of volatile constituents and Japan driers, the chemist
cannot separate the three substances and produce three
vials containing raw linseed oil in the state in which it was
used, and the drier in an unaltered condition. The volatile
solvent, if it be benzine, is the only one of the three that
can be recovered in any approach to its original condition.
The literature on raw linseed oil is very incomplete,
and more attention should be paid by chemical experts
and writers to the subject of identification of linseed
oil as it really exists in the paint.
In the chapter on the "Analysis of Oils" it will be
seen that when the iodine number of an oil is 180 the
same oil when extracted from mixed paint may show no
and still be absolutely pure, for the reason that the
metallic salts which have been added to the oil in the
form of Japan or other siccatives have in a measure
saturated some of the bonds of the linseed oil, so that
less iodine or bromine is absorbed.
l62 CHEMISTRY AND TECHNOLOGY OF PAINTS
Linseed oil dries by oxidation, and this oxidatioii is
hastened by the addition of bases or salts of lead and
manganese. There is no doubt that some of these act
catalytically, and there is likewise no question that some
of these driers continue to act long after the oil is phys-
ically dry. In drying, raw linseed oil is supposed to
absorb as much as i8 per cent of oxygen, but in actual
practice where solid linseed oil is used as an article of
commerce it seldom absorbs more than lo per cent of
its original weight. The addition of a drier has much to
do with the life of a paint, there being no two driers
that act exactly alike. If it is the intention of the paint
manufacturer to make a paint that will last the Jongest,
he must study the chemical and physical characteristics
of the drier which he uses. Red lead (PbjOO added to
linseed oil at a temperature up to 500° F., will make a
very hard drying film which in time becomes exceedingly
brittle. This can be very easily demonstrated if the red
lead oil be coated on cloth and its effect closely watched.
On the other hand, the addition of litharge to linseed oil
produces the opposite effect, and an exceedingly elastic
film is produced. The various manganese salts all act
differently and are frequently used to excess. Manganese
starts the drying operation, the lead salts continue it, and
the manganese again hastens the end. Borate of man-
ganese is, perhaps, the least objectionable of all man-
ganese salts, but the black oxid or peroxid is most
largely used, and if not used in excess is an exceedingly
valuable assistant in the dr>ang of linseed oil.
These driers are usually prepared by adding the oxids
of lead and manganese to melted rosin. After a resinate
of lead and manganese is produced, a small quantity of
linseed oil is added and the mixture then cooled either
with turpentine or benzine or both. There are hundreds
LINSEED OIL 163
of varieties of the so-called Japan driers, the best ones
containing the minimum amount of rosin and a certain
percentage of the dust of Kauri gum. The oil driers
are made in a similar way, excepting that no rosin is
used, and these driers do the least harm. Lime is very
frequently used in addition to oil, sometimes in con-
junction with rosin and sometimes alone, in order to
produce a drjdng effect. The so-called lime oil will dry
with a hard and brittle film. The salts of lead and man-
ganese are not as good for mixed paint purposes as they
are for technical purposes. The chloride of manganese
when added to linseed oil reacts upon it, and in the
presence of any moisture in the oil will liberate traces of
hydrochloric acid. Sulphate of manganese and lead
acetate will act similarly, and wherever there is a trace of
liberated acid in paints their rapid and uniform dr>'ing
is interfered with. Zinc sulphate and lead sulphate are
also excellent driers. It is considered good practice to add
a small amount of calcium carbonate wherever these
driers are used in order to neutralize the acidity, and
when this is done no ill effect can be observed. Prob-
ably the most flexible drier is Prussian blue, which is
soluble in linseed oil at 500° F., and produces such a
flexible film that the patent leather industrj- is based
upon it.
Some twenty-three years ago the author manufactured
a new drier which is an improvement on Prussian blue.
Briefly described, this drier is made out of a by-product
Prussian blue which is treated with an alkali in the
presence of calcium oxid and water. A brown powder is
the result, which has no uniformity of color but has
given excellent results as a drier. This brown has been
erroneously called "Japanners Prussian Brown," or
Japanese brown. It is soluble in linseed oil at 500° F.,
ICH CHEXtlSTRV AND TECHNOLOGY OF PAINTS
ami produces a film which is neither too hard nor too
s*.^ft. but remarkably elastic and admirably adapted for
m;iking certain paints and varnishes. It cannot, how-
ever, be said to replace any of the good linseed oil driers
for mixed {xiints, where too flexible a paint is not desir-
able, jxirticularly on steel work or exterior work, as
bUster> are likely to result from the difference in expan-
5iioa. Howex^er. as a base for the manufacture of enamel
vantishes and oils this drier has proved itself admirably
adapt^xt.
tiiisiwt oil IS a glyceride of several fatty acids, and
tcwkowit^i^h h;is pRwed that water wall replace the
glywridc radical and hydrolize the oil. (See "New Paint
^'ouvlitions Kxisting in the New York Subway" by
\Li\iituUau l\Kh, Journal of the Society of Chemical
liulustrw No. lo, VoL XXIV.)
The action between a fat and a caustic alkali in boil-
it\i: soluttvMU by which a soap is formed and glycerin set
trvv\ IS tvv well known to need further discussion. The
'aVs\ .uivls which are amibined with the soda can be
■ilv:\i:ov'. l>v the addition of almost anv mineral acid to
fae sv\r.v rru> >vr^K>nirication can be produced by the
a.i v^tv V •. u.itvT aloue on raw linseed oil. WTiere a paint
V v>v.tai:i> I;:r,o .^r U\ui this hydnilysis probably is hastened.
We iia\c hcriL^ an excellent explanation of the so-
ealled ih^:\>us w.Usilities. or non-waterproof qualities, of
linseed vnl as a :\uut» which is further brought out by
I he uut that \\b.e:\ lius^vd oil is treated with Prussian
hUie vM laparuaers rrussian brown it cannot be hvdrolized
In nteaus oi water» for the acid radical has formed a com-
pK^ie V oinpvHitid with the iron in lx>th of these driers, and
the prv^lvM\gal heaiini: has volatilized the glycerin. Con-
Mviuentlw when a paint is made by the treatment of
lin>eed vmI at a temjxTature of over 500° F., with a
>
* ■
LINSEED OIL
165
neutral and soluble base like the ferri-ferro cyanide of iron,
the resulting film is not linseed oil nor a linoleate of any
base with free glycerin, but a complex compound com-
posed of the various linseed oil acids united with iron.
This gives us the basis of waterproof paints. This is
ex-ident from the quality of patent leather, which is not
only much more flexible than any paint made in the
ordinary way, but is likewise waterproof.
The following are the probable formulas for linseed
oil in its various stages:
CsHfi
Pb
Mn
Mn
Pb
Fe
C16H26O2 1
C16H28O2 • Raw linseed oil.
C18H32O2.
CieHaOz+On
CieH2802 + On r Japan and linseed oil.
CisHaOz-hOnJ
rCieH2602-hO„
C,eH2802-hO„
. CisHajOz -h On .
Ci6H2602+On
CieH2«02-hOn
.Ci8H8202-hOn.
Boiled or varnish oil.
Waterproof oil.
There are questions in regard to the physical and
chemical characteristics of linseed oil on which there has
been considerable discussion and naturally a difference
of opinion. The first is whether linseed oil dries in a
porous film, and the second is whether linseed oil while
drying goes through a breathing process during which
it absorbs oxygen and gives off carbonic acid and water.
With reference to the porosity of the dry film of linseed
oil, the following extract is made from the Journal of
the Society of Chemical Industry (May 31, 1905, "New
Paint Conditions Existing in the New York Subway''
by Maximilian Toch).
l66 CHEAflSTRY AND TECHNOLOGY OF PAINTS
"In a paper before the American Chemical Society
on March 20, 1903, I gave it as my opinion that a dried
film of linseed oil is not porous, excepting for the air
bubbles which may be bedded in it, but that any dried
film of linseed oil subjected to moisture forms with it a
semi-solid solution, and the moisture is carried through
the oil to the surface of the metal. We then have
two materials which beyond a doubt have sufficient
inherent defects to produce oxidation under the proper
conditions, and granted that the percentage of carbon
dioxid in the air of the tunnel is not beyond the normal,
the fact that carbon dioxid together with moisture would
cause this progressive oxidation is sufficient warrant for
the discontinuance of paints that are not moisture and
gas proof. Dr. Lewkowitsch demonstrated in his Canton
lectures that the fats and fatty oils hydrolized with
water alone, and linseed oil is hydrolized to a remarkable
degree in eight hours when subjected to steam. It can,
therefore, be inferred that water will act on linseed oil
without the presence of an alkali, and that calcium added
to water simply hastens the hydrolysis by acting as a
catalyser. This, then, bears out my previous assertion
that a film of linseed oil (linoxyn) and water combine to
form a semi-solid solution similar in every respect to
soap, and inasmuch as we have lime, lead, iron and
similar bases present in many paints, it is almost beyond
question that these materials aid in the saponification
of oil and water/'
If a drop of linseed oil is spread on a glass slide and
one half of it covered with a cover glass, it will be readily
seen under the microscope that the dried film is as solid
as the glass itself, that there are no pores nor any
semblance to a reticulated structure visible in the oil,
and the author therefore makes the statement with
45- 1* 13 a glass flask of about a litres capacity. Through the lube A 3.4 grams of refined
seed oil, which had been heated lo 400 degrees E. for one hour, were introduced and well
itributed over the inner surface of ihe fiask. Dry oxygen free from COi was blown through
i flask, by means of tubes A and C, until the flask contained pure oxygen. The lube A was
;n sealed, as shown in sketch, mercury brought uji into Ibc manomelcr by elevating B lo ihe
■sition shown. The flask was ihen filled with oxygen at atmospheric pressure and effectually
kicd. As drying proceeded atid oxygen was absorbed, the diminished pressure was reaiJ off
the manometer. When this became constant the funnel which was connected to A by a rubber
be was filled with filtered Barium Hydrate solution, and (he point at A broken, allowing this
run into the flask without admission of air. In a few minutes Barium Carbonate was formed,
owing condusivcly that ujme CC^ had been generated by the oil.
167
1 68 CHEMISTRY AND TECHNOLOGY OF PAINTS
absolute certainty that linseed oil dries with a homo-
geneous film in all respects similar to a sheet of gelatin
or glue.
The question as to whether linseed oil goes through a
breathing process, absorbing oxygen and liberating car-
bon dioxid and water, is one of great importance and
one which the author has worked out very carefully with
positive results. In the illustration a piece of filter paper
two inches in diameter was dipped in linseed oil of known
purity and suspended in a flask in air absolutely free
from CO2 and water. Investigators have always com-
plained of the inability to obtain tight joints in an
experiment of this kind, and in order to be certain that
there was no leakage all joints were covered with
mercury after having been first shellacked. The mano-
meter gave a curve which indicated the drying, a
thermostat being a part of this instrument, so that
absolutely uniform conditions were obtained. At the
end of thirty days the drying curve was obtained, and
when the baryta water was led into the bottom of the
flask there was hardly a trace of turbidity to be noted.
This experiment was repeated many times, always with
the same result, and the amount of water or moisture
obtained could not be weighed. It was therefore reason-
able to conclude that the linseed oil gave off neither CO2
nor water, but had absorbed oxygen.
The author, however, concluded that this experiment
was entirely too delicate, inasmuch as only one gram of
linseed oil was absorbed by the paper. Therefore, an
apparatus was devised as shown in the illustration,
without joints and so absolutely air-tight that the ques-
tion of leakage could not arise. The flask was filled with
linseed oil and then emptied by replacing the oil by air
free from water and CO2, the inside and bottom of the
LINSEED OIL 169
flask being left heavily coated with linseed oil which had
been previously heated to 400° F., for one hour. The
manometer tube formed a part of this apparatus, and
when the oil had dried completely (which was manifest
by its wrinkled and bleached appearance and likewise
by the manometer indication) a rubber tube was attached
to the point E, a funnel inserted, and a filtered solution
of barium hydrate was allowed to run in as soon as the
tip E was broken. After ninety seconds the solution of
barium hydrate turned milky, showing conclusively that
CO2 had been generated in the drying of linseed oil.
The next experiments were made quantitatively, and
while the amount of moisture could not be accurately
measured, the amount of carbon dioxid was in no case
higher than A of i per cent, whereas the absorption
of oxygen was 19 per cent. It must therefore be admitted
that linseed oil does give off CO2, but the quantity is
relatively so small that it is a question whether it should
be taken into account at all.
It is now a known fact that carbon dioxid acts as a
rust-producer on iron or steel, and if linseed oil gave off
any appreciable quantities of CO2 and water they would
act as rust-producers in themselves rather than pro-
tectors; and while it may be possible that some linseed
oils give off more of these two substances than others,
the amount under normal conditions cannot be very
great, as these experiments show.
Refined or bleached linseed oil is used to a very great
extent for the manufacture of white paints. The methods
employed for bleaching linseed oil have not undergone
very much change until lately. The coloring matter in
linseed oil is largely chlorophyll, the bleaching of linseed
oil depending not on the extraction of this chlorophyll
but on its change into xantophyll, which is yellow.
IS WL'iijliril, ihc filliT {Ki)x:r Wiis suijiL'nikil in the Krlcnmi'viT iiitsk, on
lliu trntlntii of which was a siiluLionoC Barium lly<lraie((rrefn>m CUj) toabsurl)
ihc Ci'h formtil l>y iIil- <lr«'ini; uf the oil. The flask was immvrsFd in a wuIit-
thcmiiislat, the watiT of whiih was slimil In- a revolving mcchaniral slim-r.
A ihiTmii-regulalcir.by means uf which the gos-tlamc unik-r the thermostat was
auKinialii'iilly nt;utatc<I, wus placed under the llisk. By D]x-ning the glass-
cock, u.lyi^'n was ailmitlcd frmn time to (iitic to (he Krli.-nm<'y<-r flusk, and the
alisiiqitiiin cit iixygi'n was irail on Ihc mcrcvir>--Tn:inc)nii>liT. The readings were
alwai-s marie al the same Irmjieralure. The rjxvRen, before entering the Krlen-
mivi-r flask, w:is [i^issifi Ihr.iuRh the KOEI dulh'. where it was wash.-d free fn.TU
C<).. This exiM-rimem was omcliirlea in iripUrate with girat care, the joinis
hcLnK all sealed with shellac and placeil iin.l.T iiuT.iiry. No Cf >, or H;0 beyond
a trace could Im- detemiincd, owing to the small iiuanlity of linseed oil which the
filter ))a[ier contained.
LINSEED OIL 171
Sometimes linseed oil will have a reddish cast instead
of the. usual greenish cast. This color is attributed - to
another form of organic matter known as ery^throphyll.
These three tints, the green, yellow, and red, are analogous
to the tints in autumn leaves.
. All methods for extracting chlorophyll from linseed oil
have proved extremely difficult and expensive. The ac-
cepted method, therefore, has consisted in the treatment of
linseed oil with an acid in order to convert the green coloring
matter into the yellow. This is probably the reason why
no linseed oil exists which is water white, although the
author has made several samples which are almost color-
less, but when compared in a four-ounce vial with chemi-
cally pure glycerin it can readily be noted how far from
colorless the so-called bleached linseed oil is. The method
employed for bleaching linseed oil consists in the addition
of sulphuric acid and the blowing of air into the oil at
the same time. The oil becomes cloudy and develops
small black clots. When this cloudiness is allowed to
settle out, or the oil is filtered through a filter press, it
is very much paler in color, and is then known as refined
or bleached linseed oil.
Simlight has a similar effect, the oil produced by
bleaching with light and age being superior in quality
to the sulphuric acid oil. In the sulphuric acid treat-
ment the oil, the water, and "foots," together with an
appreciable amount of emulsified oil, settle to the bottom
of the tank. These are drawn off, and are of some value
for making cheap barn paints by mixing with lime and
the oxids of iron. In another method, which produces a
still better bleached oil, chromic acid is used. If a
solution of this acid, which is blood red, be added to
linseed oil, and the mixture agitated, a ver>' much paler
and more brilliant oil is obtained, but it is rather
172 CHEMISTRY AND TECHNOLOGY OP PAINTS
expensive to produce. The treatment by means of an
electric current in the presence of moisture is likewise
used to some extent, but it appears that this method is
far more suited to other oils. Great secrecy is main-
tained among those who have a knowledge on this
subject. Peroxid of hydrogen has likewise been recom-
mended, but from the standpoint of cost the sulphuric
acid method is still the one that is used to the greatest
extent.
The new methods which are favorably spoken of, and
which the author has found to be inexpensive and
efficient, involve the use of the peroxids of calcium,
magnesium, and zinc. These peroxids are made mto
paste with water, one pound being sufficient for 200
gallons of linseed oil. This amount of oil is placed in
an open kettle or vat, together with the peroxid, and
thoroughly agitated. During agitation a strong solution
of sulphuric acid is added, which liberates nascent oxygen.
If the oil be allowed to settle, or is filtered, and is then
heated to drive oflf any traces of moisture, a very brilliant
pale oil is obtained.
It has always been understood that linseed oil con-
tained albuminous matter which coagulated at a tern-
perature of 400° F., or over, and produced a flocculent
mass. When an oil answered this reaction it was said
to "break" at the low temperature and was useless for
making varnish oil and other high grades of linseed oil.
G. W. Thompson found that this break was not due
to the presence of albuminous and nitrogenous matter,
but that it was caused by the separation of several
phosphates. This explanation has generally been ac-
cepted as correct. If an oil, therefore, is allowed to age,
the phosphates settle out and the oil does not break.
Cold-pressed linseed oil, if it breaks at all, does not break
LINSEED OIL 173
at as low a temperature as hot-pressed oil. Bleached
linseed oil does not wear as well as the oil that has been
clarified by standing.
The demand for brilliant white paints or brilliant
enamels is responsible for the manufacture of the so-
called water-white oils. From a large variety of tests
made by the author it was fully demonstrated that
white paints composed of mixtures of pigments such
as sublimed lead, zinc oxid, and white lead all showed
absolutely the same whiteness within two weeks after
they were exposed to the light, irrespective of the
kind of raw linseed oil used. One of the five tests
w^as made with a paint prepared with a linseed oil that
had not been aged for more than two months, but
within the time mentioned it was just as white as the
rest.
Linseed oil paints are supposed to deteriorate after
a few years and lose their value, owing to the decomposi-
tion of linseed oil. This statement is questionable, and
while there is no doubt that the ready-mixed paint
thickens and changes slightly in its chemical and physical
characteristics, the change is exceedingly small in a con-
tainer which is hermetically sealed. There is no doubt
in regard to the reaction which takes place between the
oil and white lead, zinc oxid, and a number of the
unstable compounds in a mixed paint. While these
reactions are very slow, they are at the same time very
definite. If the value of a paint were reduced to a
curv^e it would probably be found that the curve would
be represented by the arc of a large circle approaching
a straight line. As far as paste paints are concerned,
particularly white lead, all painters prize white lead more
highly when it is old than when it is fresh.
1-4 k:h£mistry and technology of paints
typical Analysis of Bleached, Refined Linseed Oil
S^Hxntk Gravity 932-.934
Kniine Value (Hanus) Above i8o
Sa(x>nification Value 190-194
Acid Value 3-5
Standard Specifications, American Society for .Testing
Materials, 19 14, p. 335
Purity of Raw Linseed Oil from North American Seed
Properties and Tests
I. Raw linseed oil from North American seed shall conform to
the following requirements:
Max. Min.
Sp. gr. ^^*^o C 0.936 0.932
15-5
** or — ^ C 0.931 0.927
25
Acid Number 6.00
Saponification Number 195. 189.
Unsaponifiable — per cent 1.50
Refractive Index at 25° C 1.4805 1.4790
Iodine No. (Hanus) 178.
A linseed oil may however be pure if the iodine num-
ber is 165 and it may be just as pure if the iodine num-
ber is i()5. The latter number was prevalent in the crop
SrwDAKi) Spkcifications for Boiled Linseed Oil from
North American Seed^
Properties and Tests
I. HoiliMl linseed oil from North American seed shall conform
til I 111" lollowing requirements:
I
Aiiuriean Society for Testing Materials, 191 5, p. 420.
UNSEED OIL
175
Max. Min.
Specific Gravity — - - C o-945 o-937
15-5
Acid Number 8.
Saponification Number 195. 189.
Unsai)onifiable Matter, per cent 1.5
Refractive Index at 25° C 1.484 1.479
Iodine Number (Hanus) 178.
Ash, per cent 0.7 0.2
Manganese, i)er cent ... 0.03
Calcium, per cent 0.3
Lead, per cent o.i
Navy Department Specifications
Boiled Llnsekd Oil
Composition
1. Boiled linseed oil shall be absolutely pure boiled oil of high
grade, made wholly by heating pure linseed oil to over 350° F. with
o.xids of lead and manganese for a sufficient length of time to secure
proper combination of the constituents and !)e proi>erly clarified by
settling or other suitable treatment. Evidence of the presence of any
matter not resulting solely from the combination of the linseed oil
with the oxids of lead and manganese will be considered grounds for
rejection.
Chemiral Constants
2. The oil shall upon examination show:
Unsaponifiable matter Not more than 1.5 per cent.
Lead oxid (PbO) Not less than 0.20 per cent.
Manganese oxid (MnO) . . . .Not less than 0.04 per cent.
Io<line No. (Hanus) Not less than 17S.
Specific gravity at 60° F . . . Not less than 0.938.
The oil shall give no appreciable loss at 212° F. in a current of
hydrogen.
Phvsical Characteristic
3. When flowed on glass and held in a vertical position, the oil
shall dr\' practically free from tackiness in 12 hours at a temperature
of 70^ F.
176 CHEMISTRY AND TECHNOLOGY OF PAINTS
Basis of Purchase
4. To be purchased by the commercial gallon; to be inspected
by weight, and the number of gallons to be determined at the rate of
7^ pounds of oil to the gallon.
Quantity f How Determined
5. The quantity of oil delivered in 5-gallon shipping cans will be
determined by taking the gross weight of 10 per cent of the total
number of cans, selected at random, from which the average gross
weight of the delivery will be determined. A sufficient number of
these cans will be emptied to determine the average tare, and the net
weight of the oil will be taken from the figures thus obtained.
Stand Oil
Stand oil is a very heavy, viscous form of linseed oil
which has great use in the arts for the manufacture of
both air drying and baking enamels. It is supposed that
it originated in Holland, but there is a difference of
opinion on this for the reason that the table oilcloth
manufacturers in Scotland made a similar oil under the
name of ^'marble oir^ long before the Dutch made any
enamel paints.
The method of making marble oil, which is a form
of stand oil, is simply to heat a linseed oil which has
no '^break''^ to 550° F., and to keep it at that tem-
perature or slightly over until it becomes very heavy
and viscous. Its specific gravity changes from .930 to
.980, at which point a small quantity placed on a piece
of glass and allowed to cool piles or stands up in a little
mound and runs very slowly. With the oil still at 550°
F., a small quantity of litharge is added; this is known
as adding the drier on the downward cool, which simply
' An oil from which no black flocculcnt particles separate at
500° F. is technically known as an oil which has no "break" or
does not ''break."
LINSEED OIL 177
means that the oil takes up the drier not as the heat is
increasing but as the heat is decreasing. The amount
of litharge added is necessarily ver>'^ small, because if
more than one tenth of i per cent be added the oil
becomes considerably darkened, while the object in
making an enamel oil or marble oil is to retain its color.
Oil made solely with litharge as a drier dries very tacky
and must be baked to at least iio° F. for several hours
before it will dry entirely. For this reason many add a
small percentage of borate of manganese with the lith-
arge, or chloride and sulphate of manganese, as a drier.
Of all the driers for making stand oil for enamel
paints cobalt is the best, for a very small quantity is
necessary to perform the function of drying and no bad
results are obtained. Where manganese driers are used
and continued oxidation takes place a white enamel
paint may turn entirely pink, due to the formation of a
manganese salt of that color. Where lead is used slow
and sticky drying may result, but where lead and
manganese are used together in dark colored enamels
excellent results are obtained and any change in color
value is not noticed.
Some stand oils are made also by partial oxidation or
blowing and partial heating. These, however, are short,
and when placed between the thumb and forefinger and
rubbed rapidly do not form a long thread but a short
thread. Experience has taught that a short oil is short
lived and a long oil is long lived. There is obviously a
good reason for this, as the short oil has been highly
oxidized and continues to oxidize after it is dry. Yet for
interior enamel purposes a short enamel oil will last many
years.
One of the best features of enamel oil or stand oil is
that brush marks even with a poor brush are eliminated
178 CHEMISTRY AND TECHNOLOGY OF PAINTS
and flow together. Zinc oxid is the principal pigment used
in the manufacture of all of these enamel paints.
Japanner's Prussian Brown Oil
This is a stand oil or marble oil identical in all
respects with that described under the heading "Stand
Oil," excepting that it is dark in color and therefore
only used for making dark colored enamels such as
patent leather, machinery enamels and waterproof coat-
ings which must have a high glaze.
The method used for making this oil depends very
largely upon the good quality of the linseed oil, and the
oil must have no tendency to "break" whatever. It
must be heated to 550°, at which temperature three
ounces dry or six ounces in oil of Japanner's Prussian
Brown are added slowly until the oil which at first is
muddy becomes clear and of the color and consistency
of dark honey.
As the present tendency is to varnish or enamel
automobile parts and bake them at fairly high tempera-
tures this oil has become of great value, particularly when
mixed with a fossil resin varnish, and as there are but
very few automobiles which are painted white the dark
color of this particular oil is no objection.
For the manufacture of an enamel paint for painting
engines which are continually at a temperature of be-
tween 170° and 212° F. on account of being water jacketed,
it has been found that the dark enamels used for this
purpose when made with the Japanner's Brown oil
containing at least 25 per cent of a high grade fossil
resin varnish give results that are astonishing. Enamel
paints on an engine, composed of the materials just
described, will at the end of a year be practically as good
as the day that they were applied.
UNSEED OIL 179
Typical Analysis of Heavy Bodied Blown Oil
Specific Gravity 988-.993
Saponification Value 195-210
Iodine Value 100-140
Acid Value 4-6
Typical Analysis of Enamel Oil
Specific Gravity .9678
Iodine Value i74-5
Saponification Value 1950
Acid Value 7.3
CHAPTER XIII
Chinese Wood Oil
Chinese wood oil (China wood oil), or, as it is some-
times known, Japanese wood oil or Tung oil, is very largely
used in the United States, but there appears to be very
much secrecy with reference to its manipulation.
It is a peculiar fact that the majority of writers on this
oil are inclined to condemn it, for the principal reason
that when China wood oil, as it is commonly called, is
bruslied out on a sheet of glass it dries in about 12 hours
to an opaque film which presents a rough appearance
anil does not adhere very well to the glass. It is per-
fectly true that this is a characteristic of China wood oil,
aiul it is likewise true that it has no elasticity and that
its waxlike appearance after drying condemns it very
thoroughly, but it only goes to prove the difference
between theory and practice, for, whereas China wood
oil in its raw state is totally unfit for use and spoils any
gvH>ii paint to which it may be added, when properly
treated it is one of the most remarkable paint assistants
\\l\ie!\ we have, and those who have studied the subject
earefully have made ver}^ successful paints.
It might be proper to cite as a parallel case that it
would be manifestly unfair to condemn meat as an article
ol (li(*t for tlie reason that it is tough, difficult to mas-
tic al(\ 'nsipid in its taste, and hard to digest. On the
i»tl\ir hand, the excellent flavor and nutritious qualities
\»l meat which has been properly cooked and seasoned
(olally disproves the first statement. It is evidently
180
CHINESE WOOD OIL i8i
very unfair to compare raw meat with properly cooked
meat.
In the winter time, at ordinaiy^ freezing temperature,
China wood oil looks like a mixture of tallow and sand
and has a similar consistency. The head of the cask is
removed, the oil cut out in slices and put into a kettle
for treatment.
It is pretty well agreed that at 450° F. China wood
oil gelatinizes, and if allowed to cool becomes insoluble.
But experts in the manipulation of China wood oil add
metallic salts or resinates at this temperature and a
small percentage of untreated linseed oil, and before it is
sufficiently cool small quantities of naphtha and benzol.
The resulting liquid is a clear varnish-like oil which dries
with a hard elastic film, much more slowly than the
original China wood oil. In this condition it possesses
most remarkable qualities..
By the use of China wood oil paints are made which
dry in damp atmospheres. The advantage which the
Chinese and Japanese have had over the Europeans on
this subject has been recognized for a long time. It is
now known to have been due to their knowledge of the
proper manipulation of China wood oil. For the making
of marine paints and waterproof paints China wood oil is
indispensable.
In the United States preference is given to two brands
of China wood oil; one is called the Hankow and the
other the Canton, the Hankow being the better of the
two. The Canton oil is darker, and it is wtry likely that
it is expressed from the seed by a hot process, whereas
the Hankow oil is expressed by the cold process.
The chemical constants of China wood oil are about
the same as those of linseed oil, its specific gra\dty being
slightly higher in the third decimal, its iodine value rather
l82 CHEMISTRY AND TECHNOLOGY OP PAINTS
lower, and its saponification number almost the same^ The
oil has, however, a characteristic odor which cannot be
easily destroyed, and a paint miaiiufacturer who is once
familiar with this odor can never be deceived. At the
same time, where a small quantity of China wood oil is
used for the purpose of making a particular kind of cal-
cium oleate, it loses its characteristic odor. The calcium
oleate so obtained is eventually split up by atmospheric
moisture, and is therefore valuable for making a cement
paint which has been patented.^
China wood oil is largely used in the making of enamel
paints. Such paints give perfect satisfaction, last longer,
and wear better than many of the resin varnish enamels.
This work does not treat of enamel paints, although these
paints could be classed as mixed paints, because they are
a mixture of varnish or oil and pigment. As the ratio of
the ingredients is totally different from that of oil-mixed
paints, the subject of the use of China wood oil in these
enamels has no place in this chapter. Where a manu-
facturer is at liberty to use any material, China wood
oil can in no sense be regarded as an adulterant. It is
more expensive than linseed oil and only on one or two
occasions has the price of linseed oil approximated that
of China wood oil, but even if the two in their raw state
^ The constants of a sample of China wood oil were compared with
those of linseed oil in 1906, and it is of interest to know that the same
sample was reanalyzed by the author in 1915, with the following
results.
1906 1915
0.935 Sp.gr. = 0.953 at 60'' F.
Acid Value = 8.1
190 Sapon. Val. = 194.7
165 Iodine Val. = 146.6
The oil was kept in a glass-stoppered bottle. It had become very
thick, viscous and clear.
CHINESE WOOD OIL 183
were exactly the same in price, China wood oil would be
very much dearer eventually on account of the high cost
of manipulation. All factory experience indicates that
the manipulation of China wood oil increases its cost 20
per cent if based on a cost price of 50 cents per gallon,
whereas by the same manipulation the price of linseed
oil would be increased only 5 per cent.
Tung oil is probably the glyceride of two acids —
elaeomargaric and oleic, while linseed oil is probably the
glyceride of three acids. China wood oil has two peculiar
qualities which make it very valuable for the manu-
facture of floor paints. The first is, its resistance to
moisture, and the second, its extreme hardness so that
it does not show scratch marks. For the manufacture
of floor paints for railway and steamship use, these
two qualities are essential. On the ferry-boats floating
in the rivers of the United States it is customary to wash
the floors several times a day. A linseed oil paint soon
becomes spongy and is destroyed by this treatment. A
floor paint composed of a large amount of China wood
oil and a small amount of resin does not show a heel
mark very readily, which is a decided advantage.
The Japanese are, however, more adept in the manip-
ulation of China wood oil than any other nation. The
author has three samples of varnish oil, one of which
has almost the consistency and appearance of chemically
pure glycerin. It has a faint yellowish tinge, and while
it is no better in its physical characteristics than the
nominally treated China wood oil, it indicates that
without destroying any of its good qualities the Japanese
can prepare this oil for lacquer and enamel purposes until
it is practically water white.
It is a known fact that there has been great secrecy
among the paint and varnish makers on the question of
i84 CHEMISTRY AND TECHNOLOGY OF PAINTS
China wood oil, and those who have used it successfully
have forged ahead of their competitors. Its moderate
use in a waterproof paint or damp-proof pamt is of great
benefit. Its use as a mixing varnish or combining
medium in mixed paints is likewise of great value.
In its constants it is analogous to linseed oil, and it
always has a most characteristic odor by which it can be in-
variably distinguished. It is, however, frequently subjected
to adulteration with cheaper oils, and one of the first
samples the author ever received was shipped from China
in a 5-gallon kerosene tin which contained a considerable
quantity of kerosene, either accidentally or intentionally.
The oil from Canton, according to the experience of the
author, is by no means as good as the oil from Hankow,
the Hankow oils being paler in color and responding
more clearly to the accepted chemical constants. One
of the best tests for the determination of the purity of
China wood oil is to heat it very slowly in boiling water
for an hour; then transfer the test to a naked flame and
heat it for twenty minutes to 450° F. Some care must
be exercised not to flash the oil nor to char it. It is
then allowed to cool, a good method being to place it in
cold water for half an hour, after which time the oil
must assume the appearance of an almost solid gelatin.
The admixture of any adulterant, particularly cotton-
seed oil, prevents the coagulation or semi-solidification
of China wood oil.
In order to manipulate China wood oil for paint
it must be treated with an organic acid salt of lead
and manganese which is sold for the purpose. A
number of paint manufacturers have treated China
wood oil with great success in the following manner: 10
gallons of China wood oil are slowly heated in a copper
kettle to 350° F., and 10 pounds of this organic salt are
CHINESE WOOD OIL 185
added. When entirely dissolved, which takes but a very
short time, 5 gallons of refined linseed oil are slowly
stirred in and the whole heated to 400° F. and kept at
that temperature for half an hour. The kettle is now
withdrawn from the fire, and 2^ gallons of either tur-
pentine or benzine, or a mixture of both, are added.
This oil, known as China base oil, is then used in varying
proportions in mixed paints for smoke stacks, floor
paints, and varnishes, according to the experience or
knowledge of the manufacturer.
The chemical detection of China wood oil is still
somewhat empirical when it is contained in paints or
varnishes. Some years ago the author made the state-
ment that China wood oil could always be identified to
a greater or lesser degree on account of its '^ heathen"
odor. Anyone familiar with China wood oil or while
cooking it can identify it at once. This may be em-
pirical, but it is just as positive as the odor of fish
oil when heated, and as the chemist has to depend to
quite some extent upon his sense of taste and smell,
the sense of smell when heating a varnish under exam-
ination is a fair guide when oils which have a specific
odor are contained.
Formerly very little attention was paid to the acid
figure of China wood oil, but today this acid figure plays
a very prominent role. It is definitely known now that
the high acid number of China wood oil prevents it
from being used for making enamel varnishes where zinc
or lead is used, for the reason that these pigments act
as bases and thicken the resulting enamel paint. It is
therefore either necessary to neutralize the acids or to
use a pigment which is not attacked, like lithopone.
The polymerization of China wood oil is not under-
stood. According to the patent of Beringer the addition
s
1 86 CHEMISTRY AND TECHNOLOGY OF PAINTS
of a sulphur compound prevents the polymerization. The
author has made experiments using barium sulphide and
finds that i per cent of barium sulphide prevents poly-
merization, but the addition of any one of these materials,
including sulphur or selenium compounds, paralyzes the
drying quality of China wood oil.
China wood oil plays a very . important r61e in the
manufacture of flat wall paints and neutralizing fillers
and varnishes for the painting of Portland cement.
From the analyses of various types of China wood oil
that hUve come to the laboratory of the author it was
noted that its acid number is considerably higher than
•that of linseed oil, and therefore care must be taken in
the selection of the pigments with which China wood oil
is ground, or else livering will ensue. As for instance, in
the making of an enamel paint in which zinc oxid is used,
the enamel paint may keep in suspension or be preserved
as a ready mixed paint for several weeks, but at the end
of a week it will gradually grow thicker until finally it
becomes loo thick for use. This is due entirely to the
f;ui llial the free organic acid of the China wood oil
combines with the zinc or other base and forms a com-
])()un(l. Tn order to overcome this a fair knowledge of
the eiiemistry of the pigments is necessary, and neu-
Iraliziition of the China wood oil must first take place
before it is heated or converted into a varnish oil.
In a ])revious chapter which was written nearly ten
years a^o tlie author made the statement that raw
Cluna wood oil is not used to any great extent; in fact,
it has always been regarded that raw China wood oil is
decidedly unfit for use and spoils any paint to which it
ma\' be added, but since the flat wall paints and the
Portland cement i)aints have come into use the addition
of a small percentage of raw China wood oil has been
I
CHINESE WOOD OIL 187
found beneficial not only for producing flat surfaces but
for producing a surface upon which a subsequent coat
of paint will adhere better than it would to a surface
which contained no raw China wood oil.
China wood oil has particularly good qualities for
coating Portland cement surfaces, but this invention is
fully covered by patents
In the manufacture of baking enamels most excellent
results have been obtained where China wood oil is
prepared with soya bean oil at a temperature of 520° F.
with or without the presence of resins or rosin. Rosin,
of course, is not recommended in any high grade baking
or stoving varnish, because it will distill and produce
either a flat surface or one which will alligator, but the
fossil or semi-fossil resins when added to a mixture of these
two oils produce baking varnishes which are particularly
good for' the hoods of automobiles or the radiators, which
are alternately hot and cold.
A Method for the Detection of Adulteration of
China Wood Oils.^
*^\bout July 15, 191 2, there appeared a paper pub-
lished by the New York Produce Exchange, which spoke
of the Bacon method for the detection of at least 5 per
cent adulteration of China wood oils. The paper set forth
that the suspected oils were to be placed in a bath of
between 280° and 285° C. for 8| or 9 minutes. To detect
^ U. S. Letters Patent J^J"©. 813,841..
- This paper was presented by Louis S. Potsdamer before the
Eighth International Congress of Applied Chemistry, 191 2, Section
Ve, "Paints, Drying Oils and Varnishes," of which the author was the
President. This paper was written tinder the direction of the author
and emanated from the research laboratory of Toch Brothers.
i88 CHEMISTRY AND TECHNOLOGY OF PAINTS
adulteration after polymerization the oils were to be cut
with a knife, the pure oflFering little or no resistance to
cutting and showing a clean cut surface; while the adul-
terated under similar treatment displayed a ragged cut,
or else it could not be cut at all.
This was given a fair trial in the research laboratory
of Toch Brothers' paint factory, with little success, until
I decided to note the temperature of polymerization of
the various samples, adulterated and pure. I had
several samples of the pure oil, and these I made up into
stock solutions as foUows:
Pure,
5 % Adulteration with Soya Bean Ofl -
io% " " " " "
7 % " " Paraffin Oil
io% " " " "
(Soya bean and paraffin oils were chosen as representative of v^e-
table and mineral oik respectively.)
The apparatus used was such that a bath of oil
(pure soya bean oil) was placed in a nickel pot of about 8
inches diameter. In this were suspended two test tubes,
arranged to act as an air bath. The samples were placed
in tubes of slightly smaller bore, and in turn in the air
bath. Thermometers were suspended in these tubes so
that the mercury bulbs extended below the middle of the
oil under examination.
The bath was first heated to a temperature be-
tween 510° and 525° F., and the sample tubes, filled
so that the oil surface did not extend above the sur-
face of the bath, then placed in position. They were
allowed to remain in this position until polymerization
just set in, stirring once in a while with the ther-
mometers.
CHINESE WOOD OIL 189
At the point of polymerization the temperature was
noted and the tubes withdrawn from the bath. Referring
to the tables one can see that adulterations as low as 5
per cent cause a very perceptible drop in the temperature
of polymerization.
I made only three sets of oils, but from these I
obtained results on which I base my method for the
detection of adulteration. I found that the first two oils
under examination had an average polymerization tem-
perature of 553° and the third (a mixture of two sup-
posedly pure oils received at Toch Brothers' factory for
testing) a somewhat lower temperature.
Disregarding such a small discrepancy, 15° F., we
notice that the adulteration caused a decided drop in
the polymerization temperature, and as soya bean oil
is handiest to the oriental, we may expect adulteration
with this.
By the method herein described, an adulteration of
5 per cent could be detected. To settle this finally I
offer this suggestion: that the American Society for
Testing Materials now working on the standardization
of soya bean and China wood oils add the above to
their tests and so obtain a standard temperature of
polymerization in the manner described, and all oils
meeting such a temperature (or those within a small
range) call pure. It would then be a very simple matter
to detect adulteration.
Supplementing the polymerization test the specific
gravities of the oils were determined under standard
conditions (60° F.). It was noticed that the higher the
percentage of adulteration the lower the specific gravity,
and further, when the adulteration was mineral oil the
specific gravity was lowered at least four times as much
as with a similar percentage of vegetable oil.
IQO
CHEMISTRY AND TECHNOLOGY OP PAINTS
Polymerization Temperatures
Sample
Pure
Set I
Aver.
SS3
Set 2
Aver.
Set 3
Aver.
5 % Soya Bean Oil
adulteration .
io% Soya Bean Oil
adulteration .
S%ParaflinOil
adulteration .
io% ParaflSn Oil
adulteration .
SSI
554
522
1 516
502
^498
516 S16
513
513 514
1 515
552
554
519 520
514
500 476
474
518
516
489
492
553
517
475
517
491
537
503
538
535
505
500
498 499
500
494
Soo
488
492
497
490
Sp. Gr. at 60'' F.
Sample Set i Set 2 Set 3
Pure 0.9423 0.9416 0.9409
5 % Soya Bean Oil Adulteration 0.9417 0.9407 0.9391
10% " " " " 0.9410 0.9401 0.9381
5 % Paraffin Oil " 0.9348 0.9350 0.9326
10% " " " 0.9330 0.9323 0.9310
Iodine values were also made in the samples, with the following
results:
Sample Set i Set 2
Pure 160.4 158.8
5 % Soya Bean Oil Adulteration 158.0 155.4
10% " " " " 156.2 151.9
5 % Paraffin Oil " 155.2 150.8
10% " " " 143.9 143.4
The impurities make quite an appreciable lowering in the iodine
values."
Set 3
150-5
147.8
141.6
140.5
136.8
Standard Specifications for Purity of Raw Chinese Wood Oil^
Properties and Tests
I. Raw Chinese wood oil shall conform to the following require-
ments
^ Amer. Soc. Test. Materials 191 5, 423.
CHINESE WOOD OIL 191
Max. Min.
Specific Gravity ^ C o-943 o-939
Acid Number 6
Saponification Number 195 190
Unsaponifiable, per cent 0.75
Refractive Index at 25® C 1.520 1.515
Iodine Number (Hiibi 18 hrs.) 165
Heating Test (Browne's Method), minutes . . 12
Iodine Jelly Test, minutes 4
CHAPTER XIV
Soya Bean Oil^
From 1890 to 1909 the price of linseed oil fluctuated
between 30 cents and 50 cents per gallon. On a few
occasions the prices were higher, but a fair average for
the 19 years was 40 cents per gallon, although in 1896
it went as low as 25 cents. Toward the end of 1909 it
rose from 60 cents to 68 cents withm two months,
and in September, 1910, it reached $1.01 per gallon.
After that it fluctuated between that price and 75 cents.
Owing to the high price of linseed oil in 1910 many
painting operations were deferred awaiting a lower price,
or inferior material was used in place of linseed oil.
The value of menhaden fish oil had already been
recognized, and while it is admitted that fish oil replaces
linseed oil for many purposes, it is by no means a true
substitute. The principal use, however, for fish oil to-
day is in the manufacture of linoleum, printing inks, and
certain paints which are exposed either to the hot sun
or on hot surfaces.
In 1909 soya bean oil as a paint oil was practically
unknown. Since that time many investigators have
published more or less conflicting articles concerning
soya bean oil, in which even the physical and chemical
constants of soya bean oil varied to some extent. Owing
to the fact that discordant results were continually ob-
tained, it is only within the past few years that it has
' Journal of Society of Chemical Induslr>*, June 29, 1912, No. 12, Vol.
XXXI, by Maximilian Toch.
192
SOYA BEAN OIL 193
been possible to state with some degree of certainty
whether soya bean oil is a substitute for linseed oil, an
adjunct to it, or neither. The reason for this uncertainty
and discrepancy is apparent when it is stated that the
author himself has experimented with 33 different varie-
ties of soya beans, while in the records of the Department
of Agriculture at Washington no less than 280 varieties
of soya beans are listed.
From time immemorial the soya bean has been
grown in China and Japan, where it has served as one of
the staple articles of food and as the basis for a number
of food preparations. In Europe and the United States,
however, the value and uses of the bean have been but
little appreciated until very recently (1908), when, on
account of the scarcity in the cotton seed supply of the
world, soap and glycerin manufacturers began to turn
their attention to its possibilities. In Manchuria, where
by far the major portion of soya beans are grown,
practically the entire crop is available for export. The
following figures taken from the Consular Reports will
serve to show the extent of the soya bean industry during
recent years:
1909 I9IO IQII
Tons. Tons. Tons.
Total shipments of beans from
Far East 1,470,870 1,200,000 1,500,000
Imported into Europe 400,000 500,000 340,000
As the above statistics indicate, China and Japan
retain for domestic consumption practically two-thirds
of the available supply of beans. The sugar plantations
in Southern China and the rice fields of Japan annually
consume enormous quantities of soya beans and bean
cake as fertilizer, while the extracted oil is used as food
by the natives.
194 CHEMISTRY AND TECHNOLOGY OF PAINTS
In connection with the use of soya beans and soya
bean oil for edible purposes, it may be mentioned that
there has been recently established at Les Val6es, France,
a thoroughly up-to-date factory for the production of a
wide assortment of food products from soya beans.
Among the more important of these may be mentioned:
milk, cheese, casein, oil, jellies, flour, bread, biscuits,
cakes and sauces. According to Dr. G. Brooke, Port
Health Officer of Singapore, the soya bean, more nearly
than any other known animal or vegetable food, contains
all the essential and properly proportioned ingredients of
a perfect diet.
All soya beans are leguminous plants, which do not
tend to deplete the soil of nitrogen, for the typical soya
bean plant is self-nitrifying and grows in almost any
soil that contains a reasonable amount of potash. In
addition to this, the soya bean enriches even very poor
ground when used as a ground manure. This is done by
planting the seed promiscuously, allowing it to grow to a
height of about 6 inches, and then turning it in. In this
way both nitrogen and potash are given to the soil for
future use in an available form. The average height of
the soya bean plant is about 36. inches. The pods
resemble those of our sweet pea. They are about 2^
inches in length and are covered with a hairy growth.
Generally there are two or three beans in each pod.
Af,ter the oil is extracted from the bean the cake
appears to be ver>^ valuable as a cattle food, while the
leaves and stalks, if collected and set in a dry place,
make excellent silage. We thus have practically the
entire plant available for use, with the exception of the
roots.
The average composition of the soya bean varies with-
in fairly narrow limits among the different varieties
SOYA BEAN OIL
195
of soya beans. In the following table are listed the
analyses of a few of the varieties of soya beans :^
Variety
Austin
Ito San
Kingston ....
Mammoth . . .
Guelph
Med. Yellow.
Samarow. . . .
Nitro-
Water
Protein
Fat
gen free
extract
Fibre
%
%
%
/O
/o
8.67
36.59
20.55
24.41
4.00
7.42
34.66
19.19
27.61
5.15
7.25
36.24
18.96
26.28
4.79
7-49
32.99
21.03
29.36
4.12
7.43
33.96
22.72
25.47
4-57
8.00
35-54
19.78
26.30
4.53
7.43
37.82
20.23
23-65
5.05
Ash
/c
5.78
5-97
6.28
5-OI
5.85
5-85
5.82
When the author obtained discordant results from
the soya bean oil then on the market, the first impression
was that the oil might have been adulterated, but this
did not prove to be the case. The oil was, in all cases,
pure soya bean oil, but from a seed which was not par-
ticularly adapted for making a paint oil. Through the
U. S. Department of Agriculture many varieties of seeds
were received, and through the various seed dealers in
the United States quantities of seeds of all kinds were
purchased. The method of extraction followed was to
grind the seeds very finely in a mill and digest with gaso-
line in the cold. The solvent was then evaporated and
the oil recovered. Without going into any lengthy de-
tails, the percentage of oil extracted averaged 18 per cent,
and although soya beans range in color from a cream
white to a jet black it must be noted here that all the
oils extracted from the various seeds were paler than
finely pressed linseed oil, and none of them showed the
^ U. S. Dept. of Agric. Bulletin of the Bureau of Plant Industry.
196 CHEMISTRY AND TECHNOLOGY OF PAINTS
chlorophyll extract as markedly as. fresh flaxseed. On
obtaining the various samples of oil it became evident
why the discordant results were obtained, for some of
them dried within a reasonable time and some did
not.
It has been stated that soya bean oil is not as pale
as raw linseed oil and belongs to the semi-drying class
of oils. I must correct this statement; soya bean oils
made from cold pressed seeds such as Haberlandt, Austin,
Habaro, Ebony, Meyer, and Ito San give excellent results.
They have a specific gravity as high as 0.926, with a yield
ranging from 16 to 19 per cent. Furthermore, a drier
made from red lead or litharge is unsuited for soya bean
oil, but a tungate drier, which is a mixture of a fused
and a precipitated lead and manganese salt of China wood
oil and rosin, acts on soya bean oil exactly the same as a
lead and manganese drier acts on linseed oil. In other
words, a fairly hard, resistant ^nd perfectly dry film
is obtained within 24 hours by the addition of from
5 to 7 per cent of this drier.
Soya bean oil, and when I mention this name here-
after, I refer only to that suitable for paint purposes,
is the nearest oil we have to linseed, and under
the proper impetus of the Department of Agricul-
ture much of our waste and unproductive land
between Maryland and Georgia, and from the Coast
to the Mississippi, will yield productive and profitable
croi)s. The only drawback to the planting of soya
bean is the fact that it needs much water. In 191 1
many of the experimental plantings failed on account
of the drought which was prevalent in the United
States, but in low marsh land this plant ought to yield
a profitable crop. It is doubtful whether the soya bean
would grow profitably in the extreme South. In Cuba
SOYA BEAN OIL 197
the cow-pea, which is analogous to the soya bean, will
sometimes grow to a height of 20 feet, and form a thick
mat aroimd the base or abutment of a railroad bridge,
and that within a few months. This would indicate that
a soil would have to be selected where the bean would
not grow to a height greater than 5 feet, otherwise the
stalks would be too thick and it would be difficult to
harvest it. Farmers' Bulletin No. 372 of the Department
of Agriculture makes the statement that 20 lbs. of seeds
are required to the acre, and that the production is from
25 to 40 bushels, each bushel weighing 40 lbs. If this is
a fact, and since little or no fertilizer is needed, and
when fertilizer is needed a preliminary crop can be grown
and turned in to form its own fertilizer, the American
farmer should be encouraged to try this crop. Fur-
thermore, in Kentucky two crops during the summer can
be grown, for some of the soya beans that have been
tried there have ripened early, and the second crop has
ripened late, two different selections of seed having been
used. The statement has been made that soya bean
could not be harvested properly in this country on
account of the high cost of labor as compared with that
of Manchuria and Japan, but this is evidently erroneous,
in view of the fact that enormous quantities of beans are
grown in Minnesota for food purposes and harvested
by machinery. Even in Manchuria the beans are allowed
to dry and then thrashed out by means of horse power.
At any rate, if we have any difficulties now with the
harvesting of a new kind of crop, it is safe to assume that
with the American inventive genius in harv^esting ma-
chinery, appliances will be invented which will overcome
this, for the soya business has no greater harvesting
difficulties than the edible bean.
Soya bean oil appears to consist of from 94 to 95
igS
CHEMISTRY AND TECHNOLOGY OF PAINTS
per cent of glycerol esters.^ Of these 15 per cent are
saturated acids such as palmitic acid, and 80 per cent are
liquid unsaturated fatty acids containing 70 per cent
oleic acid, 24 per cent linolic acid, and 6 per cent linolenic
acid. The iodine number of soya bean oil has been
given as ranging from 121 to 124, but the Manchurian
cold pressed oil will average as high as 133.
It may be of interest to show a comparative table
here between the physical and chemical constants' of
soya bean oil of known origin like Manchurian cold
pressed oil as compared with linseed oil.
Soya Bean Oil
Name
Meyer Brown
Peking Black
Straw-
Haberlandt
Farnham
Taha
Mammoth. .
Edward
Shanghai.
yellow
Straw-
yellow
Black,
olive
saddle
Straw-
vellow
Brown
f Straw-
[ yellow
extremely
pale
pale amber
somewhat
deeper than
above
1
Black
j' med. amber
;' same depth
as previous,
olive tone
Refined linseed oil
0.9264
0.9279
0-9234
0.9234
0.9248
0.9222
0.9248
0.9257
0.9241
0.933
Acid
value
0.44
0.14
0.00
0.16
0.47
0.17
1. 14
0.63
i.o
Iodine
value
127.0
135-4
129.8
0.65 I 131.8
127.0
I18.2
I2Q.3
124.6
127.8
1 80. 1
^ H. Matthias and H. Dahle — Arch. Pharm., 191 1, 294, 424-435.
- Results obtained in the research laboratorv of Toch Brothers.
SOYA BEAN OIL 199
The specific gravity determinations were made with
the pyknometer. The iodine values were obtained in
accordance with Hubl's method. The iodine values
indicated are somewhat lower than those of cold pressed
Alanchurian bean oil. This is no doubt to be ascribed
to the circumstance that the solvent with which the oil
was extracted was driven off by. evaporation in open
vessels on the water bath, so that the oil became slightly
oxidized.
Soya bean oil which is suitable for paint purposes has
two characteristics which enable the chemist to deter-
mine whether this oil is suitable or not. In the first
place, soya bean oil when heated up to 500° F. for a few
minutes will bleach and remain bleached. Some sam-
ples which the author has examined have turned almost
water white. Linseed oil has this characteristic, but not
to the same degree. Cold pressed soya bean oil made
from the samples indicated in the previous table, when
heated to 500° F., and blown with dry air for from 5 to 7
hours, thickens exactly the same as linseed oil, and
attains a gravity of 0.960 or over. This is the surest
indication that the soya bean oil which will thicken
under these conditions and remain pale is suitable for
paint purposes. This thickened oil has excellent qualities
and advantages for making what we call in this country
"baking japans," and what are known in England as
"stoving varnishes.''
A sample of standard cold pressed Manchurian bean
oil was heated to 500° F., and blown vigorously for 7
hours after cooling to 300° F. The following results were
obtained:
200
CHEMISTRY AND TECHNOLOGY OF PAINTS
Sp. gr.
6o*»F.
Acid
value
Iodine
value iWijs.)
•
Original oil
Blown oil
0.929
0.963
2.6
1.9
1336
105.3
It is interesting to note that the acid value was
reduced by blowing. The blown oil dried in 3I days,
whereas the original sample required from 5 to 6
days.
It appears that the varnish made from a suitable
soya bean oil bakes very hard and retains an abnormal
flexibility. As regards the wearing quality of pure soya
bean oil compared with pure linseed oil for paint, the
author has had somewhat less than three years' experi-
ence, and can only say that it is not quite as good as
that of linseed oil. A 2-year exposure on a 100-foot
fence gave slightly better results for the linseed oil as to
hardness and less gloss for the soya bean oil, but a
mixture of half soya bean and half linseed oil showed
approximately the same results, while a varnish made of
25 per cent of China wood oil with 75 per cent soya
bean oil gave equally hard results as linseed oil. It is
too soon to prognosticate the value of soya bean oil for
exterior painting, but for interior painting soya bean oil
is the equal in ever>^ respect of linseed oil, and particularly
when treated with a tungate drier.
Cobalt drier will, under many circumstances, dr>' even
those soya bean oils which are not suited for paint pur-
poses, but for the present cobalt drier is rather too expen-
sive. It has been stated that from i to i^ per cent
cobalt drier will dry soya bean oil and fish oil. This is
SOYA BEAN OIL 201
practically true, but 2^ per cent is really needed to get
the proper drying within 24 hours. Cobalt Tox
Tungate^ is probably the ideal drier for soya bean and
fish oils. This drier, when present in soya bean oil
to the extent of from 5 to 7 per cent, will dry the
latter within 12 hours.
It is, of course, possible to determine and differ-
entiate a mixture of raw soya bean oil and raw linseed
oil, for the iodine values and specific gravities are good
indications, but when 25 per cent of soya bean oil is
added to a mixed paint neither the author nor any-
one in his laboratory can, in all instances, detect its
presence.
Blown and thickened soya bean oil is already used
by a number of the linoleum and table oilcloth manu-
facturers, and for printing ink purposes it presents some
advantages. For the manufacture of enamel paints
heavy bodied soya bean oil produces most beautiful re-
sults, and as perhaps 95 per cent of all enamel paints are
used for interior decorative or protective purposes in
this country its use should be encouraged.
It is not within the province of the writer to forecast
the future of any paint oil, but there is no doubt that if
a campaign of education be urged among the farmers,
particularly in those states where soil has been regarded
as unproductive, and the proper selected seeds of soya
beans are planted, no scarcity in the flaxseed crop will
ever again be a menace to the paint and varnish indus-
tries. At the time of writing linseed oil is quoted at 75
cents per gallon and soya bean oil at 55 cents per gallon.
As soon as thousands of acres shall have been planted
* So called because it was first prepared by the author. It is a
cobaltic salt of China wood oil. Unless the cobalt is trivalent, it
will not act as a drier.
202 CHEMISTRY AND TECHNOLOGY OF PAINTS
with soya beans, the proper machinery installed, and the
sale for the cake and the silage arranged, soya bean oil
will sell at from 25 to 35 cents per gallon, and after the
ground has been productive of soya beans for some time
it will be fit for the growing of even the most difficult
crops.
CHAPTER XV
f iSH Oil
We are all prone to call all oils of a fishy nature "fish
oils," and. the author desires to differentiate between the
real fish oils and the pseudo fish oils, for there are several
marine animal oils which have fishy characteristics but
which are not strictly fish oils, and which do not serve as
good a purpose as those which are strictly extracted from
fishes. Some of the fish oils — like cod liver oil — even if
they were cheap enough, are not totally adapted for
paint use. The animal oils which have always been
regarded as fish oils, but which the author calls pseudo
fish oils, and that are in the market and easily pur-
chased at a reasonable price, are whale oil, porpoise oil
and seal oil. All of these oils are by no means drying
oils, and even if they are admixed with drying oils like
tung oil and boiled linseed oil, and an additional amount
of drier added, they are peculiarly hygroscopic, and after
three months, although these oils may be apparently
dry, they become sticky when the humidity rises above
80.
The following figures represent some constants of
fish oils, the specific gravity and the iodine number
being given in each case. The iodine number is a char-
acteristic indication of the value of a fish oil for paint
purposes.
203
204 CHEMISTRY AND TECHNOLOGY OF PAINTS
Fish Oil Constants
Specific Iodine No.
Gravity Hubl,
20** C 4 hours
No. I crude whale oil o-QiQS 136.1
No. I filtered whale oil 0.9168 125.0
No. 2 filtered whale oil 0.9187 142.9
Cod oil 0.9196 147.3
Porpoise body oil 0.9233 132.3
Seal oil — water white 0.9227 143.0
Menhaden Oil
Extra bleached winter 0-9237 150.4
Bleached — refined 0.9273 161. 2
Regular 0.9249 165.7
Dark brown 0.9250 154.5
The specific gravities were determined with the aid
of the Westphal balance.
The iodine numbers were determined according to the
standard method of Hiibl.
The fish oil used for paint purposes is the variety
obtained from the Menhaden fish, and the winter bleached
is the variety to be recommended. When refined by
the simple process of filtering through infusorial earth
and charcoal its color is that of refined linseed oil, with
little or no fishy odor; in fact, in the purchasing of fish
oil for paint purposes it is well to beware of a fish oil
that has the so-called characteristic '^ fishy" odor. In
its chemical properties it is so similar to linseed oil that
it is difllcult to differentiate between them. It must
be observed that oils in mixed paints are not presented
to the chemist or practical man in their raw or natural
state, but they have been boiled with driers and ground
with pigments so that their characteristics are entirely
FISH OIL 205
altered. The old-time painter when he condemned a
mixed paint would smell it, taste it, rub it between his
thumb and forefinger, smell it again, look wise, and say
despairingly, "fish oil." As a matter of fact, the adul-
teration of paints was seldom, if ever, caused by the
addition of fish oil, for the reason that the price of a
good fish oil always approximated that of a raw linseed
oil, and there were so many other cheaper paraffin oils
to be had that the occurrence of fish oil in a mixed
paint was relatively rare. The specific gravities of fish
oils freshly made and containing no admixture of other
species, but representing the pressing of only one species,
are as a general rule below .927. Its iodine number is
so close to that of linseed oil that in its raw state, except-
ing for its characteristic odor and the Maumene test, it
is rather diflScult to differentiate these oils with cer-
tainty. The author is inclined to believe that this
characteristic odor is due to phosphorous decomposition
compounds. If a linseed oil be heated to 500° F., mixed
with Japanners Prussian brown or Prussian blue, it de-
velops acrolein, which is identical in odor with that from
the fish oil. When Menhaden oil is treated with 8 ounces
of litharge to the gallon and kept at a temperature of 400°
to 500° F., for ten hours, it thickens perceptibly and can
be reduced proportionately with naphtha, but the amount
of loss by this treatment with litharge makes it very
expensive in the end.
The results obtained from the proper grades of fish
oil warrant the use of fish oil in the hands of an intelli-
gent manufacturer, and if used up to 75 per cent pro-
duces excellent results for exterior purposes. For interior
purposes fish oil does not seem to be desirable, for it
gives off noxious gases for a long time. When fish oil
is mixed with linseed oil even up to 75 per cent it
2o6 CHEMISTRY AND TECHNOLOGY OF PAINTS
gives excellent and lasting results and does not show
any hygroscopic properties, but when used in the raw
state, particularly in conjunction with pigments which in
themselves are not catalytic driers, the results are not
satisfactory.
For some years some of the enamel leather and print-
ing ink manufacturers have adopted the use of fish oil
as a medium to replace linseed oil with excellent results,
and the enamel leather which is produced, while not so
high in gloss as that made entirely of linseed oil, is much
more flexible and possesses an unctuousness which pre-
vents it from cracking. But fish oil for leather purposes
shows a peculiar defect, and a campaign of education
will be necessary if ever this material is to be used for
the manufacture of shoes or auto tops, for fish oil, par-
ticularly when it originally has a high acid number, seems
to effloresce and give an undesirable bloom to enamel
leather, which, however, can be removed from the sur-
face by the ordinary application of either benzine or a
mixture of benzine and turpentine. At the same time,
enamel leather is very largely used for carriage and
automobile tops, and for shoes, and wherever it is used
for these purposes these products are continually polished.
Menhaden oil is the only oil, with the possible excep-
tion of China wood oil, which can be used for making
smoke-stack paints that will withstand the action of
excessive heat and light. When treated as described, its
intrinsic value is far beyond that of linseed oil, and a
smoke-stack paint made in this manner sells for one-third
more than a linseed oil paint. It is impossible, however,
to treat Menhaden oil for this purpose, except at an
excessive cost, because the acrolein developed nauseates
the workmen, the loss in evaporation is very large, and
the treatment with litharge is such that the oil must
FISH OIL 207
be thinned before it has an opportunity to compound or
semi-solidify. In its raw state, after treatment with
animal charcoal and infusorial earth, it is used to some
extent with a heavy boiled linseed oil for making water-
proof roof paints, for painting canvas, freight cars, ship
decks, etc. When mixed with linseed oil up to about
25 per cent it is extremely difficult to determine the
amount present by means of its chemical constants or
characteristics.
The following are the constants of the Menhaden oil
which is generally used in the United States for making
heat-resisting paints:
Constants of Fish Oil
Specific Gravity 0.931
Saponification 190.
Iodine Value 150-165
There is a great demand for baking japans which
shall be flexible and at the same time be so thoroughly
baked that they adhere to the surface most tenaciously
and form an excellent enamel, and for this purpose we
know that the reasonable use of fish oil improves baking
japans very much indeed.
We are also aware that along the seacoast, where
paint disintegrates very rapidly on account of the sea
air, a fairly liberal use of properly treated fish oil serves
a useful purpose.
When red lead is mixed 33 lbs. to a gallon of linseed
oil it thickens up after a very short time and becomes
unfit for use. A properly neutralized fish oil prevents
the hardening or setting of the red lead in the package,
and a paste of this material can be transported a great
distance and will last many months in a fresh and soft
condition.
2o8 CHEMISTRY AND TECHNOLOGY OF PAINTS
In the tests made by the author on fish oils and lin-
seed oil without the admixture of driers, it was found that
the Menhaden fish oil and the linseed oil dried approxi-
mately the same, but the seal oil and whale oil were
still sticky after two weeks. This may be an unfair
test, for these other oils can be manipulated with the
proper driers and they will serve a fairly good purpose,
but inasmuch as Menhaden fish oil appears to be satis-
factory for this test even without a drier its superiority
over the animal oils is apparent.
Menhaden oil should, of course, be used with a drier,
and for that purpose the best results are obtained by
means of a tungate drier. A t ungate drier is one in
which tung oil or China wood oil is boiled with a lead
and manganese oxid, and when the solution is complete
this is then mixed with a properly made resinate of
lead and manganese. Such a drier becomes soluble in
the oil at temperatures over ioo° C, and hardens the
resulting paint very thoroughly. For fabrics, however,
fish oil must be heated to a temperature of over 200° C,
and if air is injected at such a temperature the glycerides
arc expelled and thick oil is produced which, in con-
junction with the drier just named, is equally good for
printing inks. It is advisable, however, to add at least
25 per cent of either a hea\y bodied linseed oil or a raw
linseed oil which does not ''break'' before the manipula-
tion just referred to is begun.
lor stacks, boiler fronts, etc., the treatment of fish
oil up to 220° C, with litharge makes a heat-resisting
medium that is far superior to anything excepting China
wood oil, and for both heat-resisting and exposure to the
elements fish oil is superior to China wood oil.
The following is taken from the U. S. Xa\y Depart-
ment specifications for fish oil for paint purposes:
FISH OIL 209
Qualiiy
1. To be strictly pure winter-strained, bleached, air-blown Men-
haden fish oil, free from adulteration of any kind.
Chemical Constants
2. The oil shall show upon examination:
Maximum Minimum
Specific gravity o-935 o-930
Iodine number (Hanus) 165 145
Acid number 6
Physical Characteristics
3. The oil when poured on a glass plate and allowed to drain
and dry in a vertical position, guarded from dust and exposure to
w^eather, shall be practically free from tack in less than 75 hours at
a temperature of 70° F. When chilled, the oil shall flow at temper-
atures as low as 32® F.
CHAPTER X\T
MgCTTTAXEOrS OiLS
Herkixg Oil^
WiTHix recent years tbc subject of fish oils has
recetv^ cott^-demble attentioQ^ first from the leather and
SkXip msiaofiicturers and subsequenth' from the paint
chemist. Hitherto nsh o3 played the role of a rather im-
important by-pnxfaict in the course of fertilizer or "scrap"
pcvxinctioa. for which there seems to have been always
a Liru^ viemand.
.\5 the pecxiliar properties and industrial possibili-
ties of tish otts became more thcMroughly appreciated in
the light ot investigatioDS carried out by progressive
Rxanufacturers, the fish oil industr\' received a new
Uji<e of life and grew until it rix-alled in importance
:ho fertilizer indusuy to which it had prexnously been
tributar>-.
Of the numerous varieties of fish oils which have
at one time or another appeared uf)on the market, Men-
haden oil alone seems to have established itself on a firm
Kisis in the manufacture of special kinds of heat-resisting
juints. Its application, therefore, is no longer an experi-
ment: it is an established fact.
Latterlv, attention has been more particularly directed
toward seal, whale, cod, porpoise, and herring oils, with
^ \\v A. LuivNkin, Sth Int. Congress cf Applied Chemistr>'; written
in tiie n*si^an:h laborator\' of Toch Brothers under the direction of
the author.
3IO
HERRING OIL 2ii
a view to investigating their utilizability in the indus-
tries. Of these, seal, cod and porpoise body oils have
proved to be in many ways as good as Menhaden oil,
but are beyond the reach of the paint manufacturer on
account of considerations of price.
Whale oil, which is now obtainable in the form of a
clear, pale material, comparatively free from objection-
able odors, has not as yet been successfully manipulated
to give very good drying results.
In the treatment of fish oils, several considerations
must be constantly kept in mind in order to obtain the
best results:
1 . The oil must be free from high melting point
glycerides or fatty acids; or, to use the technical term,
the oil must be "winter-pressed." Most fish oils contain
a large amount of saturated glycerides of the nature of
palmitin which separate from the oils on standing for
any length of time at a low temperature. When these
have been removed from the oil, the resulting product is
found to be much more amenable to successful treatment
than it otherwise is. It would seem that these high
melting point fats tend to retard or to prevent the dr>qng
of fish oils, giving films which remain greasy for a very
long time.
2. Very frequently, oils are received which have a
high content of free fatty acids. In the case of one
sample of herring oil, this was as high as 41.9. Under
such circumstances, it is perfectly evident that the drying
of the oil would be very largely inhibited. In addition,
such an oil, used as a paint vehicle, in conjunction with
pigments like red lead, white lead, and zinc oxid will,
in a very short space of time, "liver'' up and form the
lead and zinc soaps of the fatty acids. This was very
largely responsible for the poor results obtained with the
irrxr ajtj nt^imiL^^ zs 3
Tie frss: srrj iocs £:»: Jx ritftf -whcL ^le -ofl. extracted
rnin '^ isL rj ^imrrrg ii -yy^r, s sz&iected to the
ic5:iL ic tie oeccinccfffri:iT prMnct? rnaa ibr bocfics erf
tie -fjarr 5:r :^ ji^msr tzne ttkitt S^ a?yyferrfi" neccssau^'
*-^
Ex X 3]D2S^ be rcoeBbercd tbu diicxs. which
r^ Sor TTgrfaM^ dn^ing cxisw will not. in
jKieriL nziictSai zc^j^rh-. wien otSird tor &sh oils.
Tie tiz:x2itir criers. az>i putinnilirhr the cobalt tmigates.
OLi ftcerzJh' be depe!:Kkd ii{Mxi in the case of oils which
do zj'A yjiid to the actioG of the onfimuy linseed oQ
crlrr*. p^ro-.-fded bawe\"cr. the two concfitioiKS named above
Livr l^r^zi satisned-
Tie -sTiter recently had his attention caDed to several
ZT2.it^ of herring oil, which, at fiist ^biice« appeared
desirable from the paint mannfaflnrer's standpoint.
Accordingly an investigation was started to test its
adaptability for paint purposes, and to OMnpare its be-
T.ir. T -^-th that of Menhaden oil.
Herring oil occurs in the bodies of Clupeus C. and
\'. Japanese herring varieties) and Clupeus harengus
European or North Sea herring K
The meth<xi of extracting the oil from herring is the
one universally used in the fish oil industry*, viz., ex-
traction in boiling water.
Two representative samples of herring oil, furnished
bv two of the leading oil concerns in the States, were
exiHTimented with in conjunction with Menhaden and
v>ther nsh oils. The following analytical constants were
v^btained:
HERRING OIL
213
No.
Color
Odor
Sp. Gr.
Acid
Iodine
iS°C
Value
Value
#1 Herring Oil
Very Pale
Good
0.9240
2.4
1379
§2 Herring Oil
Dark Brown
Bad
0.9210
41.9
136. 1
Blown Oil #2
Deep Red
Almost
None
0.9654
25-7
89.94
Winter-Pressed
#2
Extremely
Fair
0.920
39-4
136. 1
Refined J
Pale
«**««««««
#1 Crude Whale OU
Very Pale
Good
0.9230
0.6
136. 1
#1 Filt. Whale Oil
Very Pale
Good
0.9203
2.3
125.0
#2 Filt. Whale OU
Pale Amber
Very good
0.9222
14-5
142.9
Porpoise Body Oil
Very Pale
Very good
0.9268
2.8
132.3
Menhaden OOs
Ext. Bleached
Winter Oil
Very Pale
Fair
0.9272
05
1504
Bleached-Refined
Pale Amber
Not bad
0.9308
5-7
161. 2
Regiilar
Deep Red
Bad
0.9284
8.4
165.7
* The part of the table below the asterisk (with exception of the
acid values), is from a paper on Fish Oils delivered by M. Toch
before the Amer. Chem. Soc., Dec. 191 1, and published in the Journal
of Industrial and Engineering Chemistry.
Crude herring oil, even though very dark in color,
yields a very clear, pale product when treated with
Fuller's earth for a short time at about 250° F., and then
for some time longer, at the temperature of boiling
water. In addition the odor is considerably improved.
In the case of the crude herring oil listed above, the
sample was kept for several hours at about 60° F. to
permit high-melting fats to separate out. The portion
which remained liquid corresponded to a winter-pressed
oil. Since the acid and iodine numbers were prac-
tically unchanged it seems that the solid fats contained
saturated and unsaturated compounds in about the same
proportions as the crude oil.
214 CHEMISTRY AND TECHNOLOGY OF PAINTS
Another sample of the oil was heated to 320*^ F- and
blown with air for about 8 hours. The eflfects produced
on the constants are shown above. The oil was^ very
heavy and viscous but had the deep red color which fish
oils so readily assume. It must be noted also that the
'^fish'' odor was very faint. The reduction in acid value
would seem to indicate that the oil contained fatty acids
which were volatile at the temperature of blowing.
Attempts to dry the samples of herring oil did not
prove successful, even when very powerful driers were
used. This cannot, however, be interpreted to mean
that herring oils are, in general, not capable of drying.
Porpoise body oil and Menhaden oil, under similar
conditions, dried satisfactorily.
The blown herring oil could very well be used for the
production of smoke-stack paints and for paints intended
to resist the ^'chalking" action of salt air. Herring oil
is at present used to a certain extent in leather manu-
facture together with some of the other fish oils like
Menhaden and whale oil. In regard to herring oil, as
with many of the other materials which are being intro-
duced from time to time, the final word cannot be spoken
until many more specimens have been examined and
given a fair test.
Corn Oil
Corn oil is made in very large quantities in the
United States, and is of considerable value as a paint
material. It is seldom so much cheaper than linseed oil
or China wood oil that it is used as an adulterant for
these oils; in fact, many manufacturers would probably
use it irrespective of the price up to about 10 per cent
in certain classes of mixed paints in order to prevent
hardening or settling. A large number of paint manu-
CORN OIL 215
facturers in the United States who grind heavy paste
paints, such as Venetian reds, ochres and white paints
containing large amounts of barytes, frequently use from
10 to 70 per cent of corn oil, not because.it is any
cheaper than linseed oil, but for the reason that the
resulting mass never becomes hard in the package as it
does where pure linseed oil is used.
Corn oil has a great analogy to soya bean oil, with the
one exception that corn oil is not as pale nor can it be
bleached as pale as soya bean oil, and when it is bleached
by chemical means it dries very badly.
Com oil is known in England as maize oil. Paint
manufacturers in England appear to have very little
knowledge of this oil and regard it as a non-drying oil,
and yet com oil is even more than a semi-drying oil,
particularly when heated with strong drying oils like
China wood oil and cobalt and manganese drier. In
the textile arts, such as the manufacture of linoleum and
table oilcloth, where flexibility is desired, large quantities
of corn oil are from time to time used with excellent
results. When an oil like corn oil is used for paint
purposes in limited quantities its characteristic of slow
drying or tacky drying is eliminated if it is properly ma-
nipulated. Corn oil will take up the lead and manganese
salts just the same as linseed, but in conjunction with
linseed oil. It can be blown and can be thickened by
heat, and being very flexible it has a distinct advantage.
It has been stated, although the author has not tried this,
that for priming new wood half corn oil and half linseed
oil with sufficient drier and volatile solvent produce a
priming coat to which a second coat of linseed oil paint
will adhere perfectly.
The physical and chemical constants of corn oil
cannot be given exactly for the reason that samples var\- .
2i6 CHEMISTRY AND TECHNOLOGY OF PAINTS
Its specific gravity will run from 0.920 to 0.926; its
saponification value will average 190; and its iodine
value will average 120, although several samples exam-
ined by the author have shown as high an iodine value
as I. so.
CHAPTER XVII
Turpentine
Turpentine occupies the same relative position among
the vehicles of paints and varnishes as white lead does
among the pigments. It is impossible to say for how
many generations turpentine was the only solvent or
diluent known to the paint and varnish industry, and
therefore when other solvents were introduced they were
looked upon as adulterants.
The methods used in the manufacture of turpentine
are very well known; the sap of the Georgia pine and
two or three other species of pine trees growing in
the southern part of the United States is collected
and distilled with steam. The distillate is known as
turpentine, and that which remains behind in the still
is known as rosin (colophony). American turpentine
has a very pleasant odor, and from several combus-
tion analyses made by the author, the composition
of turpentine taken directly from the barrel as shipped
from the South corresponds absolutely with the theo-
retical formida C10H16. It has absolutely none of the
qualities of a paint preservative, but is used only to
increase the spreading power and working quality of
paint. Entirely too much stress is laid upon the value of
turpentine as a paint vehicle, and the sooner the chem-
ist and the consumer realize that turpentine is simply
an auxiliary, the sooner will better substitutes be used.
If the forestry department of this government will not
interfere with the destruction of the trees, turpentine will
become a chemical curiosity within the lifetime of many
of us, unless new trees are planted.
217
2l8 CHEMISTRY AND TECHNOLOGY OF PAINTS
American differs from Russian turpentine in odor and
in specific gravity, although in chemical composition they
are alike. The specific gra\4ty of American turp)entine
is about .865 when fresh, but it will rise as high as .90
when old. It is supposed to boil at 350° F., but that also
depends very largely on the condition of the turj>entine
and whether it has been exposed to the air. Turpentine
flashes according to the text-books, and according to the
majority of specifications that are written, at 105° F.
As a matter of fact, its flash point is 98° F. Turpentine
evaporates very slowly, and on account of this slow
evaporation it is very highly prized as a varnish diluent,
but there are paraffin products that have lately been
invented that evaporate just as slowly and leave no resi-
due behind. Pure turpentine when poured on a sheet
of filter paper should leave absolutely no residue behind,
and a drop of water poured on the paper after the tur-
pentine has evaporated must be absorbed as readily by
the paper as before it was immersed. In this regard the
petroleum naphtha solvents are identical. They will be
described in the proper chapter.
The following organic analyses of French, American,
and wood turpentines show that French turpentine and
American tuq^entine are both represented by the for-
nuihi C10H16, the American turpentine being practically
100 i^er cent pure. Wood turpentine, however, may be
shown to be 97.7 pure, the 2^ per cent of impurities con-
sisting of pyridene bases, formalin, and other wood
(lcr()m])()sition products. Since these investigations were
made in 1905, samples of wood turpentine have been
placed on the market which are so nearly identical with
the sap turpentine that it is almost impossible to dis-
tinguish them, only an experienced consumer being able
to tell the (lilTerence, the wood turpentine having a pe-
TURPENTINE
219
culiar odor which is lacking in the sap turpentine. No
matter how thoroughly a wood turpentine is purified,
there is always a smell of sawdust which clings to it and
which can be recognized by a person once familiar with
the odor. These pure grades of wood turpentine cannot
be said to be adulterants of the sap turpentine.
French Turpentine
First Analysis
Weight of sample o. 2040 grams.
CO2 obtained 0.6558 grams.
H2O obtained o. 2161 grams.
Hence, percentage comp)osition,
Carbon 87 . 67 per cent.
Hydrogen 1 1 . 87 per cent.
Total 99-54 per cent.
American Turpentine
First Analysis
Weight of sample o. 1777 grams.
CO2 obtained o- 57^4 grams.
H2O obtained o. 1923 grams.
Hence, percentage composition,
Carbon 87 . 70 per cent.
Hydrogen 12.12 per cent.
Total 99 . 82 per cent.
Wood Turpentine
First Analysts
Weight of sample o. 1891 grams.
CO2 obtained o- 59v39 grams.
H2O obtained o. 2042 grams.
Hence, percentage composition.
Carbon 85 . 65 per cent.
Hydrogen 12 . 10 per cent.
Oxygen 2.25 per cent.
Total 100.00 per cent.
Second Analysis
o. 1870 grams.
0.6009 grams.
0.1980 grams.
87 . 63 per cent.
11.87 per cent.
99 . 50 per cent.
Second Analysis
o. 1828 grams.
0.5878 grams.
0.1968 grams.
87 . 69 per cent.
12.07 percent.
99 . 76 per cent.
Second Analysis
0.1656 grams.
0.5202 grams.
0.1785 grams.
85.67 per cent.
12.08 per cent.
2.25 per cent.
100.00 per cent.
220 CHEMISTRY ASD TECHXOWCT OF PAIXTS
In the Journal of the American Cbemkal Society^
for 1904 a very exhaustive treatise is given cm ^irits of
turf)entine, in which it is demonstrated that the only
reliable chemical test for differentiating between wood
turpentine and the old spirits is the determination of the
iodine absorption number. But even this is now growing
to be very unreliable, for the reason that so much care
and skill is exercised in the manufacture of wood tur-
pentine that it is almost impossible to distinguish it
from the sap turpentine. A great deal has been written on
the optical activity of turpentine when obser\-ed through
the polariscope. The paint chemist, however, cannot
point with any degree of certainty to this test, excepting
where a coarse mixture of benzine, rosin oil, etc., is made,
and up to the present writing very highly refined tur-
pintine and sap turpentines show little or no difference.
'Hie admixture of rosin oil, benzine, benzene, kerosene,
and adulterants of that kind are, of course, differentiated
with more or less ease.
'turpentine is by no means used as largely as it was
pri<»r lo 1906. The reason for this, strange to say, is a
I Mora I one and not a physical one. Ten years ago it
would have been thought impossible to do without spirits
ol lur|)entine in paint or varnish. Today it is used by
iMiiny |)ro|)le who think they have to use it, and by others
who use it in hi^h grade piano and other finishing varnishes,
l)r< iuiM' Ihcy believe it gives a physical flow to the varnish
which cannot he ()l)tained by the use of anything else.
This, however, is (Hsputed by many manufacturers. At
aM\ rale, the fact remains that several years ago turpentine
lose Irnm a |)riee of about 40 cents per gallon to Si. 13,
lor a number of men in the southern part of the United
Stales attempted to corner the market. Before, how-
' " Analysis of Turpentine," by Jno. M. McCandless, p. 981, 1904.
TURPENTINE 221
ever, the price reached the abnormal figure of $1.13 some
of the officials of the United States Navy made exhaust-
ive experiments and showed that the turpentine sub-
stitutes of the petroleum type were absolutely as good
and served the same purpose as spirits of turpentine.
Not to go into the details of this, about five years ago
the United States Navy substituted some 70,000 gallons
of turpentine by turpentine substitute, and the resulting
paint gave just as good service and the saving in price
was very great. The men who had attempted to corner
the market and enrich themselves at the expense of others
were finally ruined, and the whole turpentine industry
received a staggering blow, from which at this date it
has not entirely recovered. The price dropped until it
hovered around 40 and 50 cents, but in the meantime
the paint industry had learned the lesson, which was of
tremendous value, that it could do without turpentine
entirely.
Turpentine ^
Distillation of Pure Gum Spirits of Turpentine
Will not begin distilling lower than 153° C.
I to 2% distilk
over
by
153° c.
50%
fi
li
ii
157° c.
80%
ii
a
ii
159° c.
85%
H
a
a
160° c.
95%
U
a
<(
165.5° c.
Sometimes
50%
n
ii
u
150° ^^
80%
ii
a
ii
160° c.
85%
li
a
a
161° c.
95% should be distilled by 165.5° C.
^ Data from J. E. Teeple, Xew York City.
222 CHEMISTRY ASD TECHXOLOGY OF PAISTS
Distillation of Steam Distilled Wood Turpeniine
Usually begins distilling at about 153® C.
50% distills over by 160° C.
80% " " " 164° C.
85% " " " 165.5° c.
95% " " " 175° C.
Sometimes
80% " " " 163° C.
85% " " " 164° C.
90/0 105-5 ^•
95/0 172 C
This hiltcr would be considered a very good grade.
Sometimes oply 60% to 70% will distill by 165.5° C- — Poor
Kradc.
Wood Turpentine
The turpentine in the United States is held in such
strong hands that the price is abnormally high, and within
the* last five years pine, sawdust, shavings, tree stumps,
and old logs have been placed in retorts and distilled
in the sanu* manner as the sap of the pine tree. A liquid
is obtained which is sold under the name of wood tur-
|)cntint' and is guaranteed by many to be absolutely the
sa nu* material as that obtained from the sap of the
Ircr. it must l)c frankly admitted that there are some
wood 1 11 rjuMi tines on the market at this writing which
an- so similar to tlie real article that it is almost impos-
sible to (lilTerentiate between them. And yet there is
always a |)eiuliar distinctive odor to these wood tur-
pfhlinis wliicli docs not exist in the pure turpentines.
Scx'cral organic analyses of this variety of wood tur-
pentine l)v the author have shown that the formula
is not ('lollhi, but that it is a most complex mixture con-
taining more than a trace of pyridene bases, formic acid.
TURPENTINE 223
formaldehyde, and other products from the destructive
distillation of wood. But wood turpentine is being
improved so continually that these impurities are being
largely removed. For exterior painting, wood turpen-
tine that contains only a trace of these impurities is
just as good as the sap turpentine, and for indoor paint-
ing it is no better than a number of the petroleum
products and costs very much more money. It cannot
be said that it has advantages in exterior painting over
the benzine products. One reason why it can be used on
exterior work and not on interior work is that the dis-
agreeable odor it sometimes gives off becomes obnoxious
to those who use it on interior work. The pure grades
of wood turpentine cost within 5 cents per gallon of the
price of sap turpentine, and judging from the large
number of concerns that have sprung up within the last
five years for the manufacture of wood turpentine and
then slowly disappeared, it is reasonable to infer that the
industry is not profitable.
AMERICAN SOCIETY FOR TESTING MATERIALS, PHILADELPHIA,
PA., U.S.A., AFFILIATED WITH THE INTERNATIONAL
ASSOCIATION FOR TESTING MATERIALS
Standard SPEancATioNS for Turpentine
Serial Designation: D 13-15
The specifications for this material are issued under the fixed
designation D 13; the final number indicates the year of original
issue, or in the case of revision, the year of last revision. Adopted,
1915.
General. — i. These specifications apply both to the turpentine
that is distilled from pine oleoresins, and commonly known as *'gum
turpentine" or "spirits turpentine," and to the turpentine commonly
known as "wood turpentine" that is obtained from resinous wood,
whether by extraction with volatile solvents, or by steam, or by de-
structive distillation.
224 CHEMISTRY AND TECHNOLOGY OF PAINTS
2. The purchaser, when ordering under these ^>ecificatioiiSy may
specify whether gum spirits or wood turpentine is desired.
The turpentine shall be clear and free from suspended matta:
and water.
Color, — 3. The color shall be ^^Standard" * or better.
Specific Gravity, — 4. The specific gravity shall be not less than
0.862 nor more than 0.872 at 15.5° C.
Refractive Index, — 5. The refractive index at 15.5° C. shall be
not less than 1.468 nor more than 1.478.
Initial Boiling Point, — 6. The initial boiling point shall be not
less than 150° nor more than 160^ C.
Distillation, — 7. Ninety per cent of the turpentine shall distill
below 170° C.
Polymerization. — 8. The polymerization residue shall not ex-
ceed 2 per cent and its refractive index at 15.5^ C. shall not be less
than 1.500.
Methods of Analysis
9. Color, — Fill a 200-mm., perfectly flat bottom colorimetric
tube graduated in hiillimeters to a depth of from 40 to 50 mm. with
the turi)entine to be examined. Place the tube in a colorimeter and
place on or under it a No. 2 yellow Lovibond glass. Over or under a
second graduated tube in the colorimeter, place a No. i yellow Lo\i-
lK)n(l glass and run in the same turpentine until the color matches as
nearly as possible the color in the first tube. Read the difference
ill (Iq)th of the tuq)entine in the two tubes. If this difference is 50
mm. or more, the turpentine is "Standard'^ or better.
10. Specific Gravity. — Determine specific gravity at any con-
venient temperature with a plummet, the displacement of which has
been accunitely determined for that temperature, or by an equally
accurate method, usin^ the factor 0.00082 for each degree centigrade
that the temperature of determination difTers from 15.5° C.
11. Refractive Index. — Determine refractive index at any con-
venient temperature with an accurate instrument, and calculate the
results to 15.5° C, usinj; the factor 0.00045 for each degree that the
temperature of determination dilTers from 15.5° C.
' The term ''Standard" refers to the color recognized as standard
by the '* \aval Stores Trade." Turpentine is of '* Standard" color
when a depth of 50 mm. in a perfectly flat polished bottom tul>c
approximately matches a Xo. i yellow Lovibond glass.
TURPENTINE 225
12. Distillation. — Use an ordinary Engler flask and condenser/
and heat the flask by placing it in a glycerin or oil bath of the general
t\T)e described in Bulletin No. 135, Bureau of Chemistry. Fit the
flask with a thermometer reading from 145° to 200° C. in such a way
that the mercury bulb shall be opposite the side tube of the flask
and the 175° mark below the cork. Place 100 cc. of the turpentine
to be examined in the flask, connect with the condenser, insert stopper
bearing thermometer, and heat until distillation of the turpentine
begins. Conduct the distillation so that the distillate passes over
at the rate of 2 drops per second. Note the initial distilling tempera-
ture and the percentage distilling below 170° C.
13. Polymerization, — Place 20 cc. of exactly 38 N (100.92 per
cent) sulphuric acid in a graduated, narrow-neck Babcock flask, stop-
pered, and place in ice water and cool. Add slowly 5 cc. of the tur-
pentine to be tested. Gradually mix the contents, cooling from time
to time, and not allowing the temperature to rise above about 60° C.
When the mixture no longer warms up on shaking, agitate thoroughly
and place the bottle in a water bath and heat from 60° to 65° C. for
about 10 minutes, keeping the contents of the flask thoroughly mixed
by vigorous shaking five or six times during the period. Do not
stopper the flask after the turpentine has been added, as it may
explode. Cool to room temperature, fill the flask with concentrated
sulphuric acid until the tmpolymerized oil rises into the graduated
neck. Centrifuge at about 1200 r. p. m. from 4 to 5 minutes, or allow
to stand for 12 hours. Read unpolymerized residue, notice its con-
sistency and color, and determine its refractive index.
NAVY DEPARTMENT SPECIFICATIONS
Turpentine
General Characteristics, — i. The turpentine must be either a
properly prepared distillate of oleo-resinous exudation of the proper
kinds of pine, unmixed with any other substance, with the character-
istic sweet odor of gum turpentine, or it must be pure wood spirits
of turpentine, refined, and freed from heavy oils and empyreumatic
or pyroligneous odors by steam distillation; both of the above shall
be clear and water-white.
Specific Gravity, — 2. The specific gravity shall not be below
0.862 or above 0.872 at 15.5° C.
^ Stillman, "Engineering Chemistry," p. 503.
2 26 CHEMISTRY AND TECHNOLOGY OF PAINTS
Refractive Index, — 3. The refractive index shall not be less than
1.468 nor greater than 1.476 at 20° C.
Boiling Point, — 4. The boiling point shall be between 152® C.
and 158° C.
Distillation Test, — 5. When 200 ex. of the turpentine is dis-
tilled, 95 per cent should pass over below 170® C.
For this test use a 300 c.c. flask, 8 cm. in diameter, with a side
tube 8 cm. from the main bulb, and the neck extending 8 cm. above
the side tube. The neck is 2 cm. in diameter and the side tube is
5 m. m. This flask should be fitted with a thermometer (reading
from 145° to 200° C.) immersed in the vapor. The mercury bulb
should be opposite the side tube of the flask and the reading 1 75** C.
should be below the cork. The distillation should be so conducted
that there shall pass over about two dropS/ of the distillate per second.
Polymerization, — 6. When 5 c.c. of the sample is treated with
sulphuric acid of specific gravity 1.84, according to the method herein
outlined, there shall remain undissolved at the end of thirty minutes
not over 0.09 c.c. The residue unpolymerized should show a refrac-
tion value between 1.50 to 1.52. It should be viscous in nature. If
the residue is water-white, limpid, and does not show proper refrac-
tion value, it should be carefully polymerized with 38 N sulphuric
acid according to Veitch (see p. 30, Bull. 135, or Cir. 85, Bureau of
Chemistry, U. S. Department of Agriculture).
Method of Polymerization. — 7. Add slowly 5 c.c. of the turpen-
tine to 25 c.c. sulphuric acid, 1.84, contained in an ordinary graduated
narrow-necked Babcock flask. Shake the flask with a rotarv motion
to insure gradual mixing. Cool, if necessar\', in ice water, not per-
mitting the temperature to rise above 60° to 65° C. Agitate thor-
oughly and maintain at about 65°, with frequent agitations, for one
hour. Cool. Fill the flask with H2SO4, bringing the unpolymerized
oil into the graduated neck. Allow to stand one hour. Read off
unpolymerized content, note its consistency and color, and determine
its refractive index.
Color Test. — S. Shake 10 c.c. of the turpentine with 10 c.c. of
concentrated hydrochloric acid in a test tube. The development,
after three minutes' standing, of a decided red color is indicative of
the presence of other usually heavy resinous oils.
Evaporation Test. — 9. When 10 c.c. of the sample are placed in
a glass crystallizing dish, 2^ inches in diameter and i\ inches high,
and evaporated on an open steam bath, with a full head of steam, for
TURPENTINE 227
three hours, the amount of residue shall not weigh more than 0.15
gram. A single drop allowed to fall on clean white paper must com-
pletely evaporate at a temperature of 20° C. without leaving a stain.
Flash Point. — 10. The turpentine must not flash below 34° C. in
Abel's enclosed tester.
II. Bidders must state specifically on proposals whether they
propose to furnish steam distilled wood turpentine or pure gum
spirits of turpentine.
CHAPTER XVIII
Pine Oil^
One of the industries which has developed as a result
of the policy of conservation in the United States is the
manufacture of useful products from resinous woods.
Enormous quantities of the latter, which in previous
years were considered of little or no use and were deliber-
ately burned in huge burners especially constructed for
the purpose, or which were simply allowed to go to waste,
are now being economically and profitably manipulated
for the recovery of turpentine, pine oil, and rosin, or the
production of tar oils, pine pitch, and charcoal.
The two commercially important methods in vogue
are, first, the steam and solvent or extraction process, and
second, the destructive distillation process.
H. T. Yar\'an2 has taken out letters patent on a
process for extracting turpentine and rosin from resinous
woods, which very well illustrates the extraction method
as practised today. Resinous wood, reduced to fine
cliii)s by passing through a wood chipper, is charged into
an iron vessel through a charging door at the top. The
wood rests upon a false bottom over a coil supplied with
superheated steam for producing and maintaining the
^ Journal of Society of Chemical Industry, June 15, 1914, No. 11, Vol.
xxxiii, by Maximilian Toch.
- The followinj^ is a list of the Varyan U. S. Patents:
No. Qi 5,400, March 16, 1909 934,257, September 14, 1909
015.401, March 16, 1909 964,728. July 19, 1910
915.402, March lO, 1909 992.325, May 16, 1911
922,369. May 18, 1909
228
PINE OIL 229
proper temperature within the iron chamber. The door
at the top and the discharge door at the bottom are
closed, and the current of superheated steam is driven
into the mass of chips. This is continued until the more
volatile turpentine has been vaporized and driven over
into the condensers. The wood in the extraction vessel
is left charged with a small percentage of heavy turpen-
tine, together with pine oil and rosin. Steam is shut off,
the excess moisture in the hot wood is removed by
connecting the vessel with a vacuum pump, and finally
a liquid hydrocarbon (boiling point, 240^-270° F.) is
sprayed over the top and allowed to percolate down
through the pores of the wood. The resinous materials
are thus thoroughly and completely extracted, and passed
into a storage tank, from which they are pumped into a
still used for separating the component parts of the solu-
tion. From the still the hydrocarbon solvent is readily
separated from the heavier pine oils by distillation under
reduced pressure, on account of the great difference in
the boiling point between the pine oils and the hydro-
carbon solvent, the former boiling between 350° and 370° F.
The pine oils are in turn separated from the rosin by
distillation with superheated steam.
Other so-called "low temperature" processes deserve
mention as possessing features of merit, although sufficient
data does not appear to be available to show their true
value when operated on a large commercial scale. The
Hough process, for example, is to be considered essentially
a preliminary treatment in the manufacture of paper
pulp from resinous woods. Chipped wood is placed in a
retort and subjected to the action of a dilute alkali. The
rosins are saponified and the soap separated from the
alkaline liquor by cooling and increasing the alkali con-
centration to the desired degree. The rosin soap may be
230 CHEMISTRY AND TECHNOLOGY OF PAINTS
sold as such, or treated with acids for recovery of the
rosin. The turpentine and pine oils are recovered either
by preliminary treatment with steam or during the early
stages of the cooking process. •
It will be noted that in the low temperature processes
the only products recovered are turpentine, pine oils,
and rosins, the first two removed by the action of steam,
either saturated or superheated, and the latter by extrac-
tion by use of a neutral volatile solvent or a saponifying
agent. The so-called "spent wood" may be used either
for the manufacture of paper pulp or as a fuel to generate
the power necessary to carry out the process.
In the destructive distillation process, the wood, in the
form of cordwood 4 ft. to 6 ft. in length and 4 in. to 8 in.
in diameter, is placed in a horizontal retort and the tem-
perature gradually raised until the wood is thoroughly
carbonized. The factor of greatest importance in the
successful operation of this process is temperature control,
as it is essential that the turpentines and pine oils be
removed in so far as is possible before the temperature at
which the rosins and wood fibre begin to decompose is
reached. The total volume of distillate, as well as the
percentage volume of each of the several fractions thereof,
is largely dependent on the degree of temperature control.
Destructive distillation of resinous wood was first
carried out in earthen trenches, the combustion being
controlled by partially covering the wood with earth.
Tar and charcoal were the only products recovered.
Then came the beehive oven, operated in much the same
crude manner, but recovering the more volatile distillates,
in addition to tar and charcoal. This was in turn super-
seded bv the horizontal retort, externallv heated, hot
gases being circulated either through an outer shell or
through pipes within the retort. Next came the bath
PINE OIL 231
process, wherein the cordwood was immersed in a bath of
hot pitch or rosin, thereby volatilizing the turpentine and
lighter pine oils and dissolving the heavier oils and rosins.
After this preliminary treatment the bath was withdrawn
and the wood subjected to straight destructive distillation.
More recently ^ a retort has been devised utilizing the
basic principle of the laboratory oil bath. The retort is
heated by means of a layer of hot petroleum oil which is
kept continually circulating between the retorts and an
outer cylindrical shell that completely surrounds the re-
tort proper. In this way it is claimed that the tempera-
ture of distillation can be accurately controlled. The
turpentine and pine oil obtained are fractionated and
rectified by subsequent steam distillation. In running the
retort the temperature of the oil bath is so regulated that
the heat inside does not exceed 450° F. before all the
turpentine and pine oil have been distilled.
The products of destructive distillation by the several
processes are in each case of very much the same general
nature, namely, turpentine, pine oils, tar oils, pine tar,
pitch, and charcoal. In some instances low-grade rosin
oils are also produced.
"Light wood" does not refer to woody fibre which
has a low specific gravity. The name originated from
the fact that this particular wood is so rich in oil and
resinous material that it is readily used for lighting fires.
In the southern portion of the United States little bundles
of *4ight wood" are for sale in strips about \ inch in
diameter and i foot long. When a flame is applied to
one of these strips of wood it becomes useful for lighting
fires, hence the name "light wood." The author has seen
"light wood" so rich in resins and oily material that by
transmitted light a thin section looked like translucent
^ T. W. Pritchard, Journal of Society of Chemical Industry, 191 2, 31, 418.
232 CHEMISTRY AND TECHNOLOGY OF PAINTS
ruby glass. It is this particular wood which is most
used for the distillation of wood turpentine, pine oil, and
rosin.
The product from that type of pine tree from which
turpentine is obtained has always been regarded as pro-
ducing two materials when the sap has been collected and
distilled. The one material is turpentine, and the other
rosin. About ten years ago, when destructive and steam
distillation of pine wood became a practical industry, a third
substance was recovered. This material, intermediate be-
tween turpentine and rosin, is now known as "pine oil."
As far as the author knows, no one has yet determined
the chemical constitution of this intermediate product of
the pine tree, which has been designated as "pine oil."
Two years ago the writer started this investigation, which
is practically finished. There is as yet no standard of
purity for pine oil, but that it has a definite chemical
composition is now fairly well established. The only
original investigation of the chemical composition of pine
oil was carried out by Dr. J. E. Teeple^ on long leaf
pine oil.
Dr. Teeple says: "The commercial long leaf oil, as
it comes on the market, is either clear and water white,
containing 3 or 4 per cent of dissolved water, or it may
have a very faint yellow color and be free from dissolved
water. The specific gravity ranges from 0.935 ^^ 0.947,
dq)cnding on freedom from lower boiling terpenes. A
good commercial product will begin distilling at about
206° to 210°, and 75 per cent of it will distill between the
limits 2ii°-2i8° and 50 per cent of it between 213^-217°.
A sample having a density of 0.945 at 15.5° showed a
specific rotation of about \^a'] -J' — 11°, and an index of
' Journal of American Chemical Society, 1908, 30,412; Journal of Society
of Chemical lndustr>', 1908, 346.
PINE OIL 233
refraction of Np 1.4830. In fractional distillation of the
oil the specific gravity of the various distillates rises
regularly with increasing temperature, becoming steady
at about 0.947 at 217°.
"If the oil consists essentially of terpineol, CioHisO,
it should be easy to convert it into terpin hydrate,
C10H20O2 + H2O, by the method of Tiemann and Schmidt.^
The conversion was found to proceed easily when the oil
was treated with 5 per cent sulphuric acid, either with
or without admixture with benzine. If agitated contin-
uously, the reaction is complete within 3 or 4 days. If,
on the other hand, the mixture is allowed to stand
quietly, the formation of terpin hydrate extends over
several months and produces most beautiful large crystals,
which, without recrystaUizing, melt at 11 7^-1 18°. When
recrystallized from ethyl acetate they melt at 118°. The
yield is about 60 per cent of the theoretical. This
forms such a simple, cheap, and convenient method of
making terpin hydrate that it will doubtless supersede
the usual manufacture from turpentine, alcohol, and
nitric acid, and instead of terpin hydrate serving as raw
material for the manufacture of terpineol, as heretofore,
the reverse will be the case."
The term "pine oil," as now understood, is the heavy
oil obtained from the fractionation of crude steam dis-
tilled wood turpentine. When the sap of the pine tree
is subjected to distillation in a current of steam the
volatile liquid — turpentine — consists almost entirely of
the hydrocarbon, pinene (CloHie). When, however, the
trunk, stumps, and roots of the same tree have been
allow^ed to remain on the ground for a number of years
and are then steam distilled, there are obtained, in addition
to th'e turpentine and rosin, certain heavier oils formed
1 Bcr., 28, 1 781.
fJT- -.r t : .•
:?uit )i ^^rirsurs r: the
Li: '-irJ-'-rT Hi 'ZUi ^Jmctl mc '-IcideC
'^. :: J. . \Lzi : r^r 7ci":i:c:i:us ocor of
-•: ^-i I: :-r :cr=: i^ei :o a con-
"— =:!::-; T-Lnri: v^icz sb:uld drsr
r- -r^ -:.:< i^. rr- iir-r^r. It is
-• :r-:, iUfi TLar." :r rie icid resins
'.:::.- -' :k:rara:r xier: ihey ire in-
■ ■-:: --r^z .ili A-il r^rrii:- to-zether
. : :.:. . '.nc u riz .e U5ei ::• j. con-
.- - lilucr.: in 2::r:«:i:-IuI«:se >:iUt:ons,
" -^ " '"■ ^ 7rr-:. ui :ccj.^:-5 his
^ ■ -c >.-.rci :h;i: these re-
■----.:.■: F:-c vl [5 ^^ ^-e-^- and
- . •■ ■^:-.j.r.s JL subs:::ure for
* -"■ ■ '- '- *'r.er materials now
• - " '-'V-^ ;ci:u!:ar to itself, and
-V - "> ::-j.Mt* value.
. :..:::.• blc contains a small
. ^ .„:: :.. : v.hich it clings rather
- . • r/.tj.r-s a simple matter to
., ..' A rjithtr complex apparatus for
/^
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dehydrating the material is necessary with temperature
control, but the test which the author has devised for
the determination of water is quite simple. If 5 c.c. of
pine oil are mixed
with I c.c. of a neu-
tral mineral oil, like
benzine, kerosene, or
benzol, and a per-
fectly clear solution
is obtained on shak-
ing, no water is pres-
ent; but if there is
any water present in
the pine oil the water
appears as a colloid,
and a milky solution
is obtained which ™ °™ ™ "" '"" '" ^
J * ,. Fifi- VI.
does not separate
after long standing. The fact that pine oil will take up
a considerable quantity of water and still remain clear
makes it useful for emulsion paints such as are very much
in vogue at the present time for the interior of build-
ings, and it has been suggested that the addition of water
up to 5 per cent for such a purpose is beneficial on
new walls. The United States Bureau of Chemistry • has
developed a method for the determination of moisture
by the use of calcium carbide; this is being investigated
by the author but on account of its being a gas-volu-
metric method it is not quite feasible for general use in
technical laboratories.
.\ number of commercial samples of pine oil were de-
hydrated and analyzed. The tables following indicate
the results obtained: —
■ U. S. Dept. Agricuitur
, Bure^ku of Chemistr)'. Circular 9
236
CHEMISTRY AND TECHNOLOGY OF PAINTS
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PINE OIL
237
Table II. — Fractional Distillation of Commercial Pine Oil
Temperature
Water, 100®
174— 194. .
104 — 205.
205 — 208. .
208 — 210. .
210 — 213. .
213 — 216. .
216 — 218. .
218 —
Total
distillate
Sp.gr.
15.5° c.
2
0.882
7
0.920
18
28
0.933
0.939
53
88
0.941
0.942
94
0.942
95
99
T.\ble III. — Ultimate .\nalysis of Pine Oil
Sample Number.
I
2
3
4
5
()
t
8
9
.VvcraRc
Teri)ine<)l (theoretical)
French turpentine
.American turpentine
WVmkI turpentine
Pine oil, first runnings
Distillate pine oil, 174 — 195° C
O.
10.4
10.7
II. Q
7.6
8.5
9.6
10.4
8.9
lO.t)
9.8
10.38
2.2
3-9
6.0
CHAPTER XIX
Benzine
The petroleum products are used very largely in the
manufacture of all kinds of mixed paints, the principal
one used being that known as "benzine." It belongs to
the series of organic compounds having the general for-
mula CnH2n + 2. Although it is frequently added to paint
in its pure form as a diluent it is just as frequently added
in the form of a liquid drier which is a solution of the
original thickened drier in benzine.
Within the past ten years benzine has been so made
that its odor is not very apparent, and there is much
discussion as to whether benzine is a detriment to paint
or not. It is hardly necessary to touch upon the moral
side of this question. If a man should order a paint
made according to a given specification and free from
benzine, or to contain only turpentine as a diluent, the
addition of benzine would be a palpable fraud. It is,
however, unnecessar\^ to discuss this point. The prin-
cipal questions for discussion are, first, "Is a moderate
amount of benzine harmful to paint?" Second, "How
much benzine is permissible in paint?"
Answering the second question first, as to how much
benzine is permissible in paint, that depends entirely
upon the paint. A thick, viscous, ropy paint which is
so difficult to apply that it will not flow evenly is un-
doubtedly improved by the addition of benzine. It would
be just as much improved by the addition of turpentine;
perhaps it would be improved most by the addition of
238
BENZINE 239
kerosene, especially in the case of very quick drying
paints, since kerosene evaporates more slowly than either
benzine or turpentine. In the case of such dilution theory
fails and only practice can dictate how much diluent
can be added. In the case of a dipping paint where the
even spreading of a linseed oil paint is desirable, and
the sudden evaporation of the solvent helps to produce
a uniform coat, benzine cannot be replaced by any other
solvent.
The argument that is held forth by many, that ben-
zine is of no value in a structural iron paint for the
reason that its rapidity of evaporation lowers the dew
point, as then moisture is deposited as it evaporates, is a
most fallacious argument, although in theory it is cor-
rect. Turpentine will do exactly the same thing and so
will any other solvent, depending entirely upon the
hygroscopic condition of the atmosphere. If painting be
done in an atmosphere where the humidity is high and
the temperature near the dew point, it is always found that
it makes very little difference what solvents are used,
the condensation being apparent in any case. The
metallic structure itself lowers the dew point so that
the painting is being conducted on a film of invisible
water, to the detriment of the paint and to the detriment
of the metal. On the other hand a series of experi-
ments made on this subject showed that where the dew
point and the humidity are high, condensation easily
occurs even though the percentage of moisture in the
atmosphere is relatively small. (See "Causes of Rust in
the Subway," Journal of the Society of Chemical Indus-
try, 1905, No. 10, Vol. 24.) A great advantage is to be
obtained by the moderate use of benzine, for in brushing
on a quick-drying paint containing benzine the evapora-
tion carries with it much of the moisture in the paint.
240 CHEMISTRY AND TECHNOLOGY OF PAINTS
The low price of benzine in America oflFers a great
temptation for its unlimited use. In France and Ger-
many, where the petroleum products are more expensive
than they are in America, and more particularly in
France, benzine is not regarded so much as an adulterant.
However, the physical effects of benzine have been so
thoroughly overcome since turpentine has reached such
an abnormal price, that a number of most excellent
brands have been placed on the market as substitutes,
all of which are equal in physical characteristics to
pure spirits of turpentine. The objection, of course,
to kerosene as a diluent in paint is that it may carry
a small percentage of paraffin oil that has a tendency to
produce a "bloom" on paint and particularly on varnish.
Quite a large number of petroleum products have
been placed on the market which are so closely analogous
to turpentine that were it not for the odor, or lack of
odor, it would be very difficult to differentiate them. As
an instance it may be cited that turpentine is a better
solvent for some of the mixing varnishes and fossil and
semi-fossil resin driers than benzine, but the newer
petroleum or paraffin compounds, some of which have had
marked success, are absolutely identical in solvent power,
speed of evaporation, and viscosity, to turpentine, and
while the polymerization acid test would clearly show that
they are not turpentine, they can by no means be said to be
inferior in working quality or solvent power to turpentine.
The method bv which these benzines are made consists
in passing certain paraffin oils over red-hot coke in con-
junction with wood turpentine. The product which is
obtained has little or no odor. Thick or \dscous paints,
particularly the varnish and enamel paints, are so much
improved by the addition of these materials that even an
inexperienced painter will notice the free-flowing quali-
BENZINE 241
ties of the material to which these diluents have been
added.
The petroleum products used in the manufacture^ of
paint are principally 62° benzine, which means benzine
having a specific gravity of 62° Baumfi. Some of the
other naphthas ranging from 71° to 88° are used, but
these are so light and bring so much higher prices than
the 62° that they are not used as much as the 62° naph-
tha. The newer grades, however, which approach tur-
pentine in physical characteristics, must be counted on as
an important factor in paint on account of the extremely
high price of turpentine, and the fact that it is strongly
held in a few hands. On account of the decreasing amount
of this product, substitutes must be recognized. After
all, any solvent, whether it be benzine, turpentine,
naphtha, benzol or acetone, is nothing but a solvent and
evaporates completely, leaving the other vehicles to pro-
tect the paint. Of course, too much solvent is a detri-
ment to paint, no matter what kind it may be.
Benzine^
Engler Distillation of Commercial ^^^ Naphtha
Sp. Gr. (Westphal) 15.6° C 0.651
Np25° 1.3695
Temperature % Wt. Sp. Gr. 15 . 6° C. Np 25°
50® 47.7 0.609 1-3605
50° to 75° 29.2 0.65 1-3756
75° to 100° 6.8 0.70 I 3930
Residue 1.4 .... 1.4061
Engler Distillation of Commercial 62° Naphtha
Sp. Gr. (Westphal) 15.6^ o. 732
Np 25"^ 1. 4106
^ Richardson & Mackenzie, Amer. J. of Sc. XXIX, May, 1910.
242 CHEMISTRY ASD TECHXOiJOCY OF PAIXTS
Tcmf>erature
^cWu
Sp.t
r* 3
ljF. 20 20
c.
*>p2^
50'
....
so; to 75'
1.2
I 3S3O
75'^ lo 100^
20.0
0.7029
I 3956
100'' to 125''
51 9
7286
I. 4061
125" lo 150**
24.6
0.7462
I. 4168
Kcniiduc
9.2
I.42S2
CHAPTER XX
Turpentine Substitutes^
When coal is distilled in the dry form volatile hydro-
carbon gases are liberated, which when condensed form a
liquid which has great value in the arts, and is generally
called crude benzol. Its composition really is about 60
per cent of benzol, the balance being toluol, xylol and
solvent naphtha. The latter three are homologues of
benzol. It is estimated that over forty million gallons
of these solvents have been wasted in the United States
in smoke and vapor in the manufacture of coke, but at
this writing great efforts are being made to collect the
vapors economically and to put in additional ovens for
the manufacture of these by-products, so that it is very
likely that both benzol and toluol will soon be sold again
at normal prices. At this writing both benzol and toluol
have risen from 25 and 30 cents per gallon to $1.25 and
$7.00 per gallon respectively, owing to the great European
war and to the small amount of benzol and toluol manu-
factured in the United States. These materials have
been sought for very eagerly for the manufacture of both
carbolic and picric acids and trinitrotoluol.
Benzol
This material was for many years known under the
name of benzene, and here it must be noted that the
benzene which is equivalent to benzol is always spelled
^ In the chapter on "Turpentine" the author has related how
turp)entine substitutes came into their own on account of the excessive
price of turpentine.
243
244 CUEMISTRY ASD TECHXOWGV OF PAJXTS
benzene, and the light naphtha obtamed from paraffin
crude oil is spelled benzine.
Benzol is the first volatile liquid which is recovered
when coal tar is distilled. Benzol when pure is color-
less has a pleasant odor, a specific gra\^ty of 0.879 and
a boiling point of 191° F. It flashes practically at air
temperature. It crystallizes into a solid at the freezing
I)oint of water and has a peculiar analogy to water
inasmuch as it melts again at about 37° F. It is insoluble
in water but is soluble in alcohol, ether and petroleum
nai)htha. Its formula is CeHc; it attacks, though it
does not dissolve, all forms of linoxyn, which it wrinkles
and removes from the base. It is for this reason that
it is so valuable as a paint remover.
Benzol has remarkable solvent properties for many
things which contain water, such as a number of the
soaps, and is therefore invaluable to the paint manu-
facturer when used in small quantities, for it prevents the
livcring or saponification of many of the paints which have
alkaline tendencies, and which would become unfit for
use if it were not for the small quantity of benzol
added.
The addition of benzol to mixed paints to be used
for |)riining purposes has been found to be very advan-
taj^eous, on account of the fact that a firmer bond is
formed between a j^riming coat and the wood, so that
when benzol is found in a mixed paint recommended for
|)riiniiiK purposes it must be looked upon as a valuable
ingredient.
The addition of a ver\' small percentage of benzol to
mixed i)aints does no harm, but if a paint made with
hen/ol and intended as a priming coat be used as a
linishing coat it is (juite likely to attack the ground coats
and produce a shriveled cfTect.
TURPENTINE SUBSTITUTES 245
The theoretical chemist will sometimes make a mistake
when he finds benzol in a black mixed paint by reporting
the presence of coal tar, from the false reasoning that if
benzol is present coal tar must be present, because benzol
is a constituent of coal tar. A chemist must, therefore,
be very careful in drawing such a conclusion, for the
presence of either coal or pine tar in a paint can be
determined by other methods.
Toluol
Formula, CeHsCHs
Toluol is very closely related to benzol, has practically
the same specific gravity but a trifle lower — .869 to .87 —
a freezing point of 30° F., and a boiling point of 230°.
It does not flash at air temperature, and therefore
is of considerable value where high flash paints are
wanted.
In the manufacture of turpentine substitutes out of
paraffin or petroleum naphthas the addition of toluol is
of great value, particularly where refractory gums are
to be dissolved. As for instance, cold petroleum naph-
tha added to a manila varnish will practically throw it
out or precipitate it out, whereas the addition of toluol
prevents this, depending upon the amount of toluol that
the solvent contains.
It has been recommended, and from experiments made
it appears to be a fact, that toluol added to a paint in a
quantity not over 10 per cent is of great value in the
painting of cypress wood, but it is doubtful whether it
is any better than pine oil, which can be used more
liberally and which has even more penetrative effects
and a higher flash point than toluol.
246 chemistry and technology of paints
Xylol
Formula, C6H4(CH3)2
Xylol really consists of three isomers having boiling
points of 278° and 287° respectively. It cannot be very
well separated by distillation. Xylol has all the char-
acteristics of toluol but is not used to any great extent
in the paint industry on account of its high price.
Solvent Naphtha
This is a mixture of different hydrocarbon compounds
which have not yet been very well worked out; but sol-
vent naphtha has a very disagreeable odor, which no
one has been able to remove up to the present time, and
therefore its use in the paint industry is very limited.
When someone will discover a method for deodorizing
solvent naphtha it probably will replace many of our
solvents, as it is really a better solvent than anything we
know of at present, and even dissolves such materials
as gutta percha, balatta and many forms of rubber.
Its specific gravity is the same as that of xylol and toluol,
but it boils at a much higher temperature, depending
upon its composition, from 300° F. to 360°.
CHAPTER XXI
Cobalt Driers^
The cobalt compounds which are generally offered on
the market today may be divided into two classes. In
the first are cobaltous oxid, acetate, sulphate, • chloride,
nitrate, hydroxid, and basic carbonate. In the second
class are various grades and qualities of resinates (some-
times called sylvinates), both fused and precipitated,
oleates or linoleates, oleo-resinates, tungates and resino-
tungates, besides some other liquid preparations com-
posed in whole or part of the foregoing.
From the varnish manufacturer's standpoint the
substances in the first division are crude materials which
are utilized in the production of the compounds in the
second class, and also in the preparation of some var-
nishes, liquid driers, drying oils, and the so-called paint
oils. The materials enumerated under the second class
are the result of a varnish maker's labor, and when
properly made and used in mixtures to which they are
adapted give very good results.
The inorganic salts of cobalt do not directly come
under the scope of this paper, and thus will not be
directly considered except inasmuch as their use as crude
material affects the driers into whose composition they
enter.
It is only within the past three years -that the cobalt
driers have been offered to the American paint and varnish
^ By V. P. Krauss, 8th Int. Congress of Applied Chem. From
the laboratory of Toch Brothers, under the direction of the author.
247
248 CHEMISTRY AND TECHNOLOGY OF PAINTS
manufacturers. Up to the present time their use is not
general, first, because of the very high price, and second,
because their use is not thoroughly understood. Many
experimenters have had unsatisfactory results and there-
fore refused to further consider the introduction of
the new material. Furthermore, not all of the cobalt
driers, whether liquid, paste, or solid, now offered for
sale, are properly made and truly adapted to the pur-
poses for which they are recommended. This situation,
in addition to unsatisfactory results obtained by some
of those experimenting, would naturally have a retarding
effect on the introduction of a new type of material.
The salts of cobalt which are at our disposal in com-
mercial quantities are all of the cobaltous or divalent
type. It has been found that although they can be
readily used in the manufacture of driers and worked
like the various compounds of manganese, lead, zinc,
calcium, aluminium, etc., the organic compounds formed,
which are the basis and active principles of the so-called
driers, are not efficient while in the cobaltous state.
The cobaltic combinations, however, are ver}' active
driers, and it is for the formation of trivalent cobalt
c()mi)ounds that we strive in the making of driers. This
transformation can be effected in several ways. By blow-
ing cold, heated, or ozonized air through the hot cobal-
tous drier stock, or by the introduction of liquid or solid
oxidi/in^ agents. The use of cold or even heated air is a
\vvy long and tedious operation if carried out to the
I'xlciit to which it is necessary' in order to get the maxi-
nnini strcngtli in the drier, and greatly adds to the cost
of an already expensive material. The use of the liquid
or solid oxidizers can be carried out successfullv and in a
comparatively short time, although even when great care is
exercised the batch of material is in danger of catching fire.
COBALT DRIERS 249
Since driers are used in a number of industries in
which drying oils form part of the material produced,
and since the operating methods of the various manu-
facturers are widely divergent, the siccatives or driers
adapted to each will in many instances show widely
different characteristics, not merely in form but also in
composition.
Since the paint manufacturer and also the practical
painter who mixes his own paints from paste colors and
raw or treated oil are the principal consumers of what
are generally known as driers, the materials adapted for
their use may be first considered. The driers will, in
practically all instances, be in the liquid state either very
fluid, of heavy consistency or of a semi-paste nature.
In composition, they will mostly consist of resinates,
tungates, oleates, or linoleates, or combinations of the
three. For the drying of linseed oil, when the proper
driers are selected, little or nothing can be asked in ad-
dition to those known at present. When the general lead,
manganese and other prevalent metallic driers are well
chosen raw linseed oil can without any difficulty be made
to dry by the addition of from 5 to 10 per cent or even
less, the time of drying under average weather conditions
being from 10 to 24 hours. By the use of cobalt driers,
the same drying effect can be obtained when only from i
to 3 per cent of a liquid drier is used. The author is not yet
prepared to say positively what the ultimate effect of cobalt
driers is upon paint films, but from the experiments made
it is deduced that cobalt has not the harmful progressive
oxidizing action that some of the usual manganese-lead
compounds have. It has also been noticed that although
a cobalt drier may be fairly dark in color, it will not have
as darkening an effect as one of the usual driers of like
color would have upon a white paint. The cobalt driers
250 CHEMISTRY AND TECHNOLOGY OF PAINTS
likewise show the same phenomena as some of the
others when used in excessive amount; that is, that
although the paint film will set up well in the usual time
the drying action apparently reverses and the film remains
tacky.
The terms applied to liquid driers are often uncer-
tain and apt to be misleading. There are no general
standards for strength or consistency, and, it must be
admitted, ma-ny of the materials found on the market
contain more volatile thinners than is conducive to
obtaining a maximum drying effect with a minimum
quantity of drier.
The value of the cobalt specialties depends not on
their power to dry linseed oil, but on their ability to
make the lower priced semi-drying oils act like it.
Soya, fish, and even corn and cottonseed oil are
adaptable for use in paint, and when correctly treated,
increase its durability.
In the making of waterproof fabrics, insulating coat-
ings, etc., both liquid and solid driers are used. In the
linoleum, oilcloth, patent leather, artificial leather and
similar industries, the semi-liquid, paste, and solid driers
arc in demand since for these products the manufactur-
ers cook the oils and varnishes in their own factories.
The paste and solid driers must essentially be con-
sidered under the caption of crude materials because
they must be churned or cooked in the oils or varnishes
in which they are used.
The methods of making both the solid and liquid
driers are in general similar in the first stage of the
process, and thus may be described under the same
headings.
Resinate of Cobalt; Precipitated and Fused, — This is
correctly made by saponifying rosin or colophony with
COBALT DRIERS 251
caustic soda or sodium carbonate, care being taken to
avoid an excess of the reagent, and then precipitating
with a solution of some salt of cobalt. The chloride or
sulphate serve best for this purpose. The precipitated
resinate, or as it is sometinaes called, rosinate or sylvin-
ate, must then be thoroughly washed, and then pressed
and dried. This will yield a pinkish, fairly fluffy powder
when ground, which will readily dissolve in oil at a low
temperature. The fused variety is made by melting the
dried resinate in a kettle and then pouring into cooling
pans. The operation is performed more rapidly by
taking the cakes from the presses and driving off the
water and fusing in one operation.
Cobalt Oleates or Linoleates. — The basis of this class
is generally linseed oil, although walnut, perilla, soya,
and some other oils may be used. The oil is thoroughly
saponified with caustic soda, and, like the resinate, pre-
cipitated with a salt of cobalt. The material is then
carefully washed and pressed. It may be melted to form
a dark viscous heavy fluid.
Several samples of cobalt linoleate examined
consisted of bodied linseed in which small amounts
of inorganic cobalt salts had been dissolved. Another
was of the same order with the addition of volatile
solvents.
True linoleate of cobalt, wheu fused with varnish
gums and dissolved in volatile oils, yields an excellent
drier.
Oleo-resinates. — This type of drier is made by melting
together the precipitated resinate and linoleate, some-
times with the further addition of fused fossil gum-
resins.
Tungate of Cobalt. — Like the linoleates, the tungate
of cobalt is made by saponifying pure China wood oil
252 CHEMISTRY AND TECHNOLOGY OF PAINTS
(tung oil) with caustic soda, care being taken to avoid
excess of caustic,- and then precipitating with a salt of
cobalt. The tungate is then washed thoroughly, pressed
and generally dried and fused. Great care is necessary
in the preparation of a tungate since it oxidizes very
rapidly, and the oxidized material is useless.
Like the linoleate of cobalt, the tungate may be fused
with the resinate to form what may be called a resino-
tungate.
In general the foregoing substances are incorporated
in oils by means of heat, the combining temperature be-
ing between 300° and 500° F. The amount necessarj' will
vary from about | per cent to 5 per cent. In order to make
liquid drierSy the paste or solid driers can be melted alone
or in combination with gum-resins, bodied linseed oil, or
both, and then thinned to liquid consistency with volatile
oils.
Among other cobalt salts, some of the chemical manu-
facturers offer the acetate, with directions for its use as a
drier. All agree that between two and four tenths of i
per cent are necessary to dry linseed oil. The oil should
be at a temperature between 300° and 400° F., and be
carefully stirred until all the salt is dissolved. Sova and
China wood oil may be similarly manipulated.
It is still a little too soon to make a positive state-
ment as to how oils thus treated with the acetate with-
stand wear and exposure.
Cobalt oxide, like the acetate, can be directly added
to oil (luring boiling. It, however, dissolves slowly and
necessitates heating to high temperature; the resulting
product is also very dark, and mostly consists only of
bodied oil. Rosin also will directly combine with cobalt
compounds on heating together in a suitable kettle or
container. The product possesses a number of objec-
COBALT DRIERS 253
tionable features. It still is mostly unchanged rosin,
has become much darker and lost considerably in weight
due to volatilization. The effect on oils of quite a number
of cobalt compounds was tried, but none equal in efficiency
to those described in the foregoing was found.
CHAPTER XXII
\
I
COMBINING MEDIUMS AND WATER
Combining Mediums
In certain classes of mixed paints, particularly house
paints which are made of corroded lead, sublimed lead,
barium sulphate, etc., there is a likelihood or tendency of
the pigment to settle. This is more marked in the case
of corroded lead than in any of the other pigments. To
prevent this, in a measure, water is added, and up to a
certain percentage (i per cent) both the manufacturer and
the consumer have accepted the fact that water is not
injurious when added for the purpose of combining the
paint; but beyond this percentage its effect is likely to be
injurious.
Sometimes for the sake of an argument, but more
often for the sake of making a paint which contains no
more water than the natural moisture of its constituents,
a manufacturer feels the necessity of adding a combining
medium other than water to prevent the paint from
settling hard in the package. Among these are gutta-
percha solutions, solutions of balata, para-rubber, gum
chicle, etc. The rubber solutions mentioned serve their
I)urf)ose very well without injuring the paint, and the
percentage used is so small that it may be considered
negligible. This, however, is not true of many of the
mixing varnishes which are made by varnish manufactur-
ers who have no experience in the manufacture of paint.
They sell rosin varnishes neutralized with lime, lead, or
254
COMBINING MEDIUMS AND WATER 255
manganese, and while they assist very well in combining
the lead with the oil, the wearing quality of the paint is
proportionately reduced.
Within the last few years a new combining medium
has appeared on the market which in itself is an improve-
ment on all paints. It is made by melting a mixture of
a resin (free from rosin or colophony) and heavy linseed
oil, and reducing with China wood oil and naphtha.
Where a manufacturer uses a combining medium of this
character the paint becomes more viscous as it grows
older, and when it dries it produces a satin-like gloss and
shows fewer brush marks than a paint containing water.
Water in the Composition of Mixed Paints
The question of how much water shall be added to
mixed paints, or how much water mixed paints shall
contain, either added or incidental, is not fully decided
upon, as there is a difference of opinion as to its value,
and likewise a difference of opinion as to the amount
necessary for certain purposes. There are some paints in
which 83 high as 2 per cent of water is necessary, and in
other paints less than i per cent is purposely added.
That water is of great benefit in certain paints cannot
be disputed, one large railway corporation permitting
the addition of i per cent of water to its mixed and
paste paints.
A chemist in making an examination of a mixed paint
must necessarily be careful in giving an opinion as to the
amount of water in the paint, and great judgment must
be used in a report. For instance, a paint, made accord-
ing to a certain specification, containing a large mixture
of Venetian red and yellow ochre, might contain very
nearly 2 per cent of moisture, which was a part of the
256 CHEMISTRY AND TECHNOLOGY OF PAINTS
composition of the pigment. Then again, linseed oil fre-
quently contains more than a trace of water, which the
manufacturer cannot extract nor can he afford the time
necessary to allow the water to settle out of the oil. A
mixed paint should not contain over i per cent of water,
for it is unnecessary to add more than this amount to
any paint.
The proper benefits derived from the addition of water
to a pure linseed oil paint are suspension of the pigment
and improvement in its working quality. Take the case
of artists' tube colors which lie on the dealers' shelves
for years and which are prone to get hard and likely
to separate so completely that the color will be found
on one side of the tube and the oil be entirely free on the
other. Water is an absolute necessity in this case and is
an improvement for both seller and user. The colors
made with the correct addition of water are known
to "pile,'' and artists prefer a color which "piles"
prop)erly.
There are many ways of adding water to a paint.
In some instances the required amount of water, together
with the oil and the drier, are placed in a churn or mixer
and the paste paint stirred in. WTiere materials like
calcium sulphate, calcium carbonate, ochre, Venetian red,
silicate of magnesia, silicate of alumina, white lead, etc.,
are used, there is no necessity for adding any combining
material which will form a soap with the linseed oil,
there being sufficient action between these materials and
the water. It is an additional advantage that there is
less likely to be complete saponification in a mixed paint
to which no "emulsifier'' has been added.
The following materials arc used for emulsifying
j)aints:
COMBINING MEDIUMS AND WATER 257
Saturated solutions of hypochlorite of lime.
Five per cent solution of carbonate of soda.
One-quarter of one per cent solution caustic soda.
One per cent solution of carbonate of potash.
Emulsion mixtures of half water and half pine oil.
Solutions of hypochlorite of lime containing twenty per cent
wood alcohol.
Ten per cent solution of borax.
Five per cent solution zinc sulphate.
Seven per cent solution \ead acetate.
Five per cent solution manganese sulphate.
Solutions of ordinary laundry soap or rosin soap in half
alcohol and half water.
Weak solutions of casein dissolved in ammonia water.
Ordinary lime water emulsified with linseed oil.
There is no license whatever for the addition of much
water to paint. Some authorities state that as high as i|
per cent is permissible, but the author does not by any
means subscribe to that, as i| gallons of water in loo
gallons of paint are far in excess of any desirable amount.
Three-quarters of i per cent or at most i per cent
would probably be a maximum, and as an explanation
of this it must be understood that materials like ochre,
clay, silicate of magnesia, white lead, calcium sulphate
and many of the pigments which contain moisture or
water of crystallization may carry a small amount of
water into paint.
Yet there may be cases where water is permissible up
to 5 per cent, but only for interior purposes. Flat wall
paints which have a tendency to settle hard can be
emulsified so as to prevent them from settling, and in a
case of this kind where the wear of the paint is not taken
into consideration there may be some excuse or license
for the addition of water.
258 CHEMISTRY AND TECHyOLOGY OF PAIXTS
To detect water in paint, particularly in light-colored
paints, is a comparatively simple matter. The method
devised by the author is almost quantitative for some
purposes. The first method ever published by the
author consisted in placing a strip of gelatin in a mixed
paint. When a measured or weighed amount of mixed
paint was taken and the strip of gelatin allowed to remain
immersed for twenty-four hours a fairly correct quantita-
tive determination was obtained. Another method de-
scribed some years ago involved the use of anhydrous
sulphate of copper, a bluish white powder, which on the
addition of water returns to the natural dark blue color
of crystallized copper sulphate.
The author has, however, devised the scheme of
using a glass plate and mixing a paint with a dyestuflf
such as "Erythrosine B." When about ^ gram of the
dye and 5 grams of mixed paint are rubbed together
with a palette knife on a sheet of glass, a paint con-
taining no water will produce a distinct pearl-gray color;
if there is water in the paint the mixture changes almost
immediately to a brilliant cerise red, and if there is much
water in the paint (over 2 per cent) the color changes
into a crimson, so that the reaction is clearly marked.
The test must not be allowed to stand more than four
minutes, since even paints which contain no added water
but which naturally contain traces of moisture will begin
to change into a rosy color, in which the presence cannot
be rci)orted. In red, black or dark colored paints Er\'-
throsine B is just as indicative of water in paint, par-
ticularly when the mixture is viewed by transmitted light.
Kvcn in the case of black paint the erythrosine emulsion
j)aint will produce a beautiful purple color.
CHAPTER XXIII
Fiyit Grinding
There is a great difference of opinion on the question
of how paints should be ground, and a careful canvas on
this subject reveals the fact that most paint manu-
facturers believe that all paints should be very finely
ground. This is a great error, for there are many con-
ditions where a paint should be slightly coarse in order
to give proper results, for if paints do not have a slight
amount of coarseness, or "tooth'' as it is called, one coat
will not hold successfully on the other, and it is for the
very reason of producing a mechanical bond that fillers
are used which have a distinct grain. Without making
any general rule on the subject, all priming coats should
have suflScient tooth to enable the succeeding coat to
hold.
Those familiar with the subject are aware of the
fact that a gloss coat on a gloss coat very frequently
peels, and the same is sometimes true of a gloss coat on a
priming coat which is too finely ground. This does not
apply to a finishing coat, because the finer a finishing
coat the longer it lasts and the cleaner it remains, for a
coarse finishing coat will hold dust and dirt which even a
heavy rainstorm will not always dislodge, while a smooth,
finely ground finishing coat acts like a glaze and remains
clean until it perishes. It may therefore be taken as a
general statement that priming coats should be slightly
coarse and finishing coats should always be fine.
259
I
26o CHEMISTRY AND TECHNOLOGY OF PAINTS
If you take the case of the finishing of a very fine
object like a piano or an automobile, rubbing varnishes
are used on the undercoat, and these varnishes are
scarified with pumice stone for two reasons: first, so as
to smooth the coat thoroughly because the succeeding
coat when applied will then itself produce a smooth and
glossy effect, and secondly, so that the next coat which
is applied can bind itself mechanically to the undercoat.
If, therefore, rubbing is a practice where varnished objects
are to be finished, it must be taken as a rule that where
paints are applied and rubbing is not practiced a slight
grain is of great benefit, so that the question of fine
grinding does not apply to every case.
CHAPTER XXIV
The Influence of Sunlight on Paints and
Varnishes^ •
It may properly be said that direct sunlight has a
vety destructive action on paint and varnish films, and
the author had noted as far back as 15 years ago that
many of the paint materials that were perfectly water-
proof in places where sunlight never reached became
permeable to water and disintegrated very rapidly when
exposed to direct sunlight. As an example of this, it
might be cited that pure asphaltum, when applied in a
good continuous coat on cast iron pipes in a cellar, will
last from three to four years, yet the same asphaltum
when applied on the roof of a building will show al-
most complete decomposition within 20 days. In order,
therefore, to determine the cause, the first experiments
with a series of bitumens were made as follows: Sheets
of clean steel and wood were painted with a variety of
bitumen compoimds and exposed to direct sunlight under
various colored glasses, finally reduced to the three
colors, violet, green, and red; for obvious reasons these
three served all purposes. It was found at the end of
four weeks that the bitumens exposed under the blue
rays showed marked signs of decomposition, those under
the green showed some signs, and those under the red
none whatever. The same experiments were tried again
by cementing the glass to the painted surface, when
little or no decomposition followed in any case. A large
^ Reprinted from the Journal of the Society of Chemical Industry',
April 15, 1908. No. 7, Vol. XXVII, Maximilian Toch.
261
262 CHEMISTRY AND TECHNOLOGY OF PAINTS
variety of experiments was then tried by mixing the
bitumens with various pigments, and a preservative
action was obtained in direct ratio to the pigment used,
so much so that a sample of paint made to contain 80
per cent of bitumen, 15 per cent of linseed oil, and 5 i>er
cent of finely divided carbon, showed only slight deterio-
ration at the end of six months; this was easily accounted
for by the fact that the finely divided carbon prevented
the absorption of many actinic rays. While these
experiments were very conclusive, it was necessary to
determine the cause, and to this end a large variety of
experiments was conducted, all of which were productive
of excellent results.
All asphaltums are bitumens, but all bitumens are
not asphaltums, and it is necessary to look into the com-
position of the asphaltums which decompose in the sun-
light and of those resins which do not. The difference
between a resin and an asphaltic bitumen may generally
be stated as follows: — Asphaltums and bitumens are
composed principally of carbon and hydrogen, w^hereas
the resins are semi-fossilized, and composed of carbon,
hydrogen, and oxygen. Asphaltums, whether they be
natural or artificial, consist largely of hydrocarbons of
the series of CnHon-o, CnH>n-4, CnHjn-s, etc., and according
to Clifford Richardson * and others, these hydrocarbons
are i)robably polymethylenes. From a large number of
combustion determinations made with bitumens, it may
be safely stated that many of the bitumens are probably
polymethylenes of various series, as above. There are,
of course, substances in bitumens such as sulphur and
nitrogen, which probably exert very little influence on
the material from an actinic i)oint of view. Assuming,
' St'c '* The Modern Asphalt Pavement " and * Origin of Asphalt/'
1)V ClitTord Richardson.
INFLUENCE OF SUNUGHT ON PAINTS AND VARNISHES 263
therefore, that the hydrocarbons are of the character
described, we should have under the combined action
of the oxygen of the air and the actinic rays of the light,
sometimes, in conjunction with moisture, a favorable
condition where oxygen would combine with hydrogen,
and carbon be set free. Therefore, if this reaction takes
place, all bitumens in a short time ought to become car-
bonized and deposit relatively pure carbon on their sur-
faces, and this is exactly what takes place, the action of
the sunlight probably resulting in a combination of the
hydrogen with oxygen, and a deposit of what appears to
be carbon takes place. If this, then, is the first lucid
explanation of the decomposition of bitumens in sunlight,
it is the explanation of the cause of the valuelessness of
pure bitumens as protective paints for exterior purposes.
Even the addition of a small amount of bitumen to a
large percentage of otherwise good paint will result in the
decomposition of this paint when exposed to the direct
action of moisture and light.
We have no such action when materials are used which
are glycerides of fatty acids, such as fish oil, Chinese
wood oil, and linseed oil. Indeed, any one of these three
oils are light-proof in a very large degree, and fish oil
and Chinese wood oil are both heat-proof and light-proof.
Linseed oil, however, unless prepared with fossil resins,
is not water-proof, but fish oil is more water-proof, and
Chinese wood oil most water-proof of all. At the same
time, pure Chinese wood oil is less light-proof, next comes
fish oil, while linseed oil is most light-proof, and there
would appear to be an established ratio that a paint or
varnish containing the least amount of oxygen is the
least light-proof and the most water-proof, and the paint
containing the largest amount of oxygen is most proof
against light, and least water-proof.
264 CHEMISTRY AND TECHNOLOGY OF PAINTS
In conclusion, and as evidence of the correctness of
these statements, if a sheet of metal or wood be painted
with asphaltum or bitumen-paint and exposed to sunlight
and air, the coating will be rapidly decomposed, and after
a lapse of 20 days probably carbon will be set free.
At least, this is a deduction from the nature of the
bitumens. Minute scrapings from the surface of exp)osed
bitumens show that the principal constituent is carbon,
and, whereas the original material contains much less,
the exposed bitumen shows over 95 per cent of carbon,
the remainder being principally hydrogen, with a small
difference, which is evidently oxygen. This shows that
the general reaction tends to produce carbon.
The painting of concrete to preserve it against the
action of moisture and frost is destined to become as large
an industrj^ as the painting of wood, and those who have
tried asphaltum paints for this purpose have already
found to their sorrow that disintegration takes place in
a very short time, even though the material be perfectly
proof against the alkaline action of the lime in the con-
crete, and as linseed oil paint is rapidly destroyed by
concrete itself, owing to the interaction of the lime and
the linseed oil, we have to look for other materials with
which we can coat concrete in order to preserve not only
its appearance, but the very structure itself.
Regarding the action of sunlight on pigments, it is
well known that lithopone is rapidly acted upon by light,
and direct sunlight turns it a dark gray, but frequently
overnight the color leaves it and it is brilliant white
again in the morning. English vermilion (mercuric
sulj)hide) is also acted upon by sunlight, and forms first
a brown comi)ound and then a black compound of mer-
cury. This has been regarded as mercurous sulphide or
as a sub-suli)hide of mercury, but on this question the
INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 265
writer has doubts. Some of the oxids oi iron, par-
ticularly the bright red ferric oxids, are affected by light,
and a compound results which from bright red turns to
brown, probably a change tending towards the formation
of ferrous oxid.
We know that a large number of the organic dyestuffs
tend to bleach in the sunlight, but sunlight alone is
never very active regarding the decomposition of colors
when air is excluded, for even mercury vermillion is
regarded as permanent when it is covered by a coat of
varnish. This is largely true of the organic lakes and
finer colors used for coach painting. Linseed oil itself
is bleached by sunlight, but this is a chemical change
produced by the actinic rays in which the green chloro-
phyll is changed to pale yellow.
CHAPTER XXV
Paint Vehicles as Protective Agents Against
Corrosion ^
A careful search of the literature of the past twenty
years has failed to reveal anything like a systematic
investigation of the relative value of different vehicles
used ifi the manufacture of paints for structural steel
and the prevention of corrosion. There are a. few isolated
cases in which boiled linseed oil,^ Kauri linseed oil var-
nish ' and spar varnish as protective coatings on structural
steel were studied. For many years past much has been
written and many investigations have been made on the
protective quality of the pigments, but no one has appar-
ently made any study of the vehicles.
It is quite obvious that without a vehicle a pigment is
useless, and the author knows of no instance where a pig-
ment could be used alone, with perhaps the single exception
of Portland cement, if that may be classed as a pigment;
even then, Portland cement would be useless unless water
were used as a vehicle. The example need hardly be called
to your attention of taking a dry pigment and using water
as a vehicle to show you that when the water evaporated
it would leave the pigment, and the pigment in turn
would leave the metal ; and yet, to the best of the author's
^ Journal of Society of Chemiail Industry, June 15, 191 5. No.
II, Vol. XXXIV, by Maximilian Toch.
- C. \'on Krcybi^, harbcn /Ag., 17, 1766-8; J. N. Friend,
Camc^ic Scholarship Report, Iron and Steel Inst., May, 191^, pp. i-g.
* Address of Prof. A. H. Sahin before .\merican Society of
C^ivil Engineers, Xov. 4, 1896, reported in Engineering Xews, July
28, 1898.
266
PROTECTIVE AGENTS AGAINST CORROSION 267
knowledge, nobody has paid any attention to the very im-
portant role that is played by the vehicle itself. There is
an old proverb which says, "One hand is useless, for one
hand washes the other," and it seems that the same is
true with reference to vehicle and pigment, for one is of
little value without the other, and if any value is to be
attached to either of them the vehicle has by far the
advantage, because there are some vehicles which protect
for a considerable length of time.
With this end in view exposure tests were made in
191 3, in which fifty- two steel plates (in duplicate) were
carefully freed from grease by washing with benzol,
dried, sanded, and rubbed clean with pumice, and then
coated with all the paint vehicles or protective vehicles
to the extent of fifty-two in number, many of which, of
course, are seldom, if ever, used alone, and some of
which are failures a short time after they are put on.
However, the author wanted to do this thing thoroughly,
and for this purpose selected the same quality of steel,
known as cutlery steel, which has been used by him for
many years for his exposure tests. It is a steel which
rusts very rapidly.
Those plates must be eliminated which have shown no
rusting in the year and five months that they have been
exposed. These were coated with the paraffin or machin-
ery oil compounds, and it would be poor advice to any
engineer to coat steel with paraffin compounds, for the
method of cleaning before the application of any good
paint would have to be very carefully followed out,
since no protective paint would hold on steel that re-
tained the least trace of a paraffin coat. Then the
paraffin, or non-drying oils, all collect a great deal of
dirt, which showed that this would have to be entirely
removed before any paint could be applied.
268 CHEMISTRY A\D TECHNOLOGY OF PAINTS
Plate No. 41 showed excellent results, and a material
of this kind would not be so very expensive where en-
gineers demand that steel be coated with a clear liquid
in the shop so that the steel may be inspected in the
field. This was composed of half spar varnish and half
stand oil. Stand oil is practically a polymerized linseed
oiL Linseed oil when heated to 550° F., with a drier
like Japanner's Prussian brown or borate of manganese
will produce a ver\' thick viscous liquid, which is largely
used as a patent leather finish. This can be reduced
with 50 per cent of thinner and still have the fluid-
ity or viscosity of raw linseed oil, and is, therefore,
inexpensive.
Plate No. 50 was coated with a material containing
10 per cent of paraffin oil, which might be classed as
an adulterated linseed oil, and while it showed up xexy
well, it could not be recommended because on an exp)osed
structure like a bridge a coat of good protective paint
would not adhere very thoroughly.
Plate No. 52 has taught a valuable lesson with regard
{o the use of raw China wood oil which is heated to a suf-
ficient ilogree of heat to take 10 per cent of a tungate
drier, and then thinned with 15 per cent of benzine. This
made a material which is hardly more expensive than
gcHxL boiled linseed oil, and left a most excellent surface
for repainting. In fad, this has proved itself the equal
o\ plates No. 22 and No. 23, with the addition of a better
surface for repainting.
Plate No. 40 was coated with kettle-boiled linseed oil,
and is very good, but this material might be regarded
h\ some engineers as too expensive for application, as
it took all dav to make this oil. A carefullv selected
linsecil oil was chosen to start with, to which was added
5 l)er cent of litharge and no other drier. This oil dried
PROTECTIVE AGENTS AGAINST CORROSION 269
very badly, but when it did dry produced a good flexible
film which lasted. This must not be confounded with
the average boiled linseed oil of commerce.
The various coatings used in these exposure tests
have been divided according to their protective value
into five classes :
1 and lb — Those vehicles "which have little or no
value for the prevention of rusting.
(a) The raw and refined drying and semi-drj^ing
vegetable oils. (Plates Nos. i, 7, 8, 13, 35, 36, 47, 48.)
(b) The same oils to which 10 per cent of drier
had been added. (Plates Nos. 2, 3, 4, 6, 9, 10, 11, 12,
14, 34.)
(c) The more or less volatile paint thinners. (Plates
Nos. 17, 18, 19, 20, 33.)
(d) Solutions of celluloid and pyroxylin. (Plates Nos.
24, 25.)
(e) The liquid (at room temp.) paraffin oils. (Plates
Nos. 21, 30.)
2 — Those vehicles which showed some degree of
protection, though not very much at best.
(a) Wood-oil varnishes containing a certain percentage
of rosin. (Plates Nos. 26, 29.)
(b) Copal-wood-oil varnishes. (Plates Nos. 27, 28.)
(c) Varnishes made from linseed oil which had been
thickened and oxidized by blowing with air, oxygen or
ozonized air. (Plates Nos. 32, 37.)
This compared with the results obtained below with
cooked-oil varnishes proves conclusively that the film
yielded by a blown oil is not nearly as waterproof and
resistant to severe weather conditions as that formed by
a boiled or polymerized oil.
3 — Varnishes or varnish mixtures which protected
the steel very nicely as long as weather conditions were
PROTECTIVE AGENTS AGAINST CORROSION 271
seed oil which contains paraffin oil in some quantities when
apparently dry shows minute globules of paraffin oil in
w^et condition when the film is heated over ioo° C. A
film of linseed oil containing lo per cent of paraffin oil
after it is six months old can be extracted with naphtha
and shows uncombined paraffin oil. These experiments
prove conclusively that it is dangerous to mix a paraffin
oil with linseed oil for any purpose, excepting where
it is not necessary, or not the intention, to repaint
subsequently.
Note: All the photographs submitted (see pages 274-
27s) were taken during December, 1914.
CHEMISTRY AXD TECHKOLOCY OF PAIXTS
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CHAPTER XXVI
The Electrolytic Corrosion of Structural Steel*
Engineers have commented publicly on the electro-
lytic corrosion of structural steel, particularly those parts
known as grillage beams, supporting columns and base
posts, which are either in the ground or surrounded by
concrete and partly above the ground, with a view of
determining beyond question at which of the poles corro-
sion occurs, and whether one pole is more active than the
other.
The author performed an experiment by taking two
sheets of high grade watch spring steel, which is ex-
tremely susceptible to corrosion, and connecting them
with the ordinary bluestone telegraphic cell. A volt am-
meter was placed in the circuit and the two pieces of steel
buried up to 5 in. in sand. Careful observation was made
every day to see that the current was uniform, and the
sand was first moistened with salt water and then contin-
ually moistened with distilled water so that the same
strength of salt solution was maintained. This experi-
ment was conducted for 100 days, and assuming that the
current travels from plus to minus, or from anode to
cathode, the anode being connected with the copper and
the cathode being connected with the zinc, corrosion was
noticed almost immediately at the anode, and the plates
showed violent corrosion at the anode and practically no
corrosion at the cathode. These plates indicated some
' By Maximilian Toch. Reprinted from Proceedings of
American Society for Testing Materials, Volume VI, 1906.
276
ELECTROLYTIC CORROSION OF STRUCTURAL STEEL 277
slight corrosion on the cathode, which, however, was
principally chemical corrosion.
The strength of the current was .05 of a volt and the
distance between the plates, varjdng in the damp sand,
was i^ inches, and the amperage varied from .02 to .05.
The current was measured by a "Pignolet," direct
reading, continuous current volt-ammeter, and the amount
of current which produced this corrosion was exceptionally
small.
Another experiment was tried exactly in the same
manner, for a shorter period of time, but instead of using
two plates, three plates were used, the third one being
designated as the "free" plate, in which chemical corro-
sion had full sway. At the end of six days these plates
were removed; the anode showed marked corrosion, the
cathode plate showing practically no corrosion at all, and
the "free" plate showed a fair average between the
cathode and the anode, and it can be deduced that the
difference between the cathode and the anode corrosion
is equal to the "free" corrosion. In other w^ords, there
is many times more corrosion on the anode than there is
on the "free" plate, and no corrosion on the cathode
plate.
The rust first produced was the green ferrous oxid,
Fe(0H)2, which, being a very unstable product, was
quickly converted in the air into FegOa, N(H20).
The current was .1 of a volt and .1 of an ampere
which produced this result. The salt solution was four
times as strong as that produced in the first experiment.
A third experiment was, however, of the greatest im-
portance, owing to the fact that the author attempted
to imitate the conditions exactly as they existed in
buildings. The same kind of steel was taken and bedded
in various mixtures of concrete, starting from neat
278 CHEMISTRY AND TECHNOLOGY OF PAINTS
cement and going up to 1:3:5. There is a -well-known
law in physical chemistry that reactions which take place
with an increase of pressure are retarded by an increase
of pressure, and the question has come up as to whether
it is possible for steel to corrode when surrounded by
concrete, many engineers holding that the alkaline na-
ture of the cement will prevent the corrosion, and others
holding that in conjunction with this condition the pres-
sure exerted by the concrete prevents chemical decom-
position. The author is glad to be able to throw some
Ught on this subject, and the following experiment was
carried out:
In the first place cement was taken of known com-
position, agreeing practically with the definition as quoted
in the Journal of the American Chemical Society, July,
1903, when the question of the permanent protection of
iron and steel by means of cement was thoroughly
gone into. The cement for these experiments was
what might be termed the tri-calcic silicate and
calcium aluminate. This is in contradistinction to the
general classes of Portland cements containing dicalcium
ferrite as a part of their composition and free calcium
sulphate in excess. A cement of the calcium aluminate
class, free from iron and free from calcium sulphate, is a
well-known protector of steel and iron against corrosion,
and this class of cement was used in these experiments.
The pieces of steel were connected up with six elementar}''
cells of sufiiciently high voltage and amperage, and it was
impossible to get a direct reading from the volt-ammeter,
the instrument being too sensitive. The seven parts of
cement containing the steel strips were then put into the
circuit and wet every few hours with solutions of 5 per
cent sodium chloride and i per cent nitric acid, and water,
in order to increase their conductivity and produce corro-
ELECTROLYTIC CORROSION OF STRUCTURAL STEEL 279
sion as rapidly as possible. The average strength of the
current was .05 volts and .05 amperes throughout the entire
experiment. Corrosion was immediately noticed at the
anode pole, and the pat of neat cement, which should have
protected the steel most perfectly against all kinds of corro-
sion, showed a hair line split colored with rust at the end
of the third day, which demonstrated that the chemical
reaction of rusting had taken place at the anode ; that the
molecular increase had likewise taken place, and the pres-
sure caused by the molecular increase had split the block.
The steel in each alternate pat was painted half the length
which was embedded in the cement with an insulating
paint of known composition having a voltage resistance of
625 volts per millimeter. The results obtained after these
various briquettes were broken open demonstrated that
electrolytic corrosion takes place most violently at the
anode unless the steel be coated with an insulating
medium.
Cement, concrete, or even neat cement, is therefore no
protection against electrolytic corrosion, unless the steel be
insulated as heretofore mentioned, and there was absolutely
no corrosion where coated with insulating material. It
must be noted that the cathode in all these experiments
was perfectly free from any signs of oxidation.
The result of this entire series of experiments is to
prove conclusively that electrolytic corrosion of struc-
tural steel embedded in concrete or sand takes place only
at the anode and there with great violence; and further-
more, that the cathode is protected by the electrical cur-
rent. The popular impression that cement is a protector
against all kinds of corrosion is fallacious. The anode
does not only rust very violently, but a molecular in-
crease of volume may take place which will split the con-
crete shell.
28o CHEMISTRY AND TECHNOLOGY OF PAINTS
Another conclusion arrived at is that the electrolytic
rusting of grillage beams of buildings need not be feared
if the structural steel be protected by a good insulating
material, but the insulating medium should form a bond
with concrete.
CHAPTER XXVII
Painters' Hygiene
All paints should be regarded as poisonous, and even
though it may be understood as a general rule that
materials like ultramarine blue are non-toxic or that
silica has no effect upon the system, it is unwise for the
paint manufacturer to permit his men either to breathe
these in dry dust form or to allow his workmen to eat
their meals before washing themselves thoroughly. We
are all very familiar with the fact that white lead pro-
duces lead poisoning, but in any well-regulated factory
there is no excuse for this, and the amount of lead
poisoning produced in factories like the large lead manu-
factories in the United States is reduced to a minimum
because the workmen are looked after most thoroughly.
Workmen who are employed in a dusty atmosphere should
always wear respirators, and workmen who work with
lead products should not be permitted to grow mous-
taches, as the dust of many of the poisonous pigments
settles in the moustache and is then absorbed through
the nose. White lead under the finger nails is absorbed
into the system, and a careful watch of these things will
prevent any disease among the men; but all in all there
is more sensationalism and hysteria on this subject than
is warranted by the results, for in paint factories where
sufficient care is taken there is practically no illness
among the men.
281
282 CHEMISTRY AND TECHNOLOGY OF PAINTS
Paint vapors are all toxic, and any painter who is
ignorant enough to apply any paint material in a closed
room does not deserve to be a painter. Even materials
like pure spirits of turpentine, which are known to have
medicinal qualities, when bre.athed in large quantities are
supposed to produce headache and vertigo, and the fumes
of benzol, benzine and alcohol give the same results;
therefore all people who apply paint should do so in well-
ventilated rooms. Large vats which are varnished on the
interior like brewers' vats, or water tanks which are
painted on the inside, are generally ventilated by the
engineers in charge by having fresh air pumped in con-
tinually to the men from the top and by simply pumping
out the vapors from below, as practically all of the
materials used in the manufacture of paint give oflF vapors
which are heavier than air.
Paint vapors are also inflammable, and any fire
resulting from careless smoking or throwing lighted
matches near paint is likely to produce disastrous results,
but much information has been disseminated on this
subject, particularly through the railroads, who now
demand caution labels printed on each package before
it is shipped with the result that many lawsuits which
were instituted formerly against the manufacturer are
not permitted today. The same is true with regard
to the vapors arising from paint. It has been a practice
among certain questionable lawyers to institute suits
against paint manufacturers for illness, headaches, nausea,
vertigo and such other physical ills as have resulted from
the fumes of paint, and few of these lawsuits have ever
been tried, because the paint manufacturer in former
times has been inclined to settle a suit of this kind
rather than go to court, but these cases are not as
frequent as they formerly were on account of the wide-
PAINTERS' HYGIENE 283
spread knowledge of the subject. Fumes arising from
paint are not dangerous in the open air, but if a painter
is careless in a closed room it is certainly his fault, and a
man who knows so little about paint should not be per-
mitted to use it.
CHAPTER XXVIII
The Growth of Fungi on Paint
Fungi must not be confounded with bacteria. Bac-
teria are invisible micro-organisms, and whether they
thrive on paints has never yet been established. Their
existence in oil or paint media has never been proved.
Experiments made by the
author in which various
bacteria were grown in
gelatin or agar agar have
^ demonstrated that when
I turpentine, benzine, linseed
I oil, vamish or jmints of
any character, excepting
^'' those containing water, were
added, they rapidly per-
ished. Fungi, howe\'er, are
K(]. 71. ()i.i\h: c.KKFv iiNcrs, srowing totally different organisms.
"," !'■''"* — '''"■"""'^'^'K'^i* ^"°°- A fungus is derived from a
spore which floats in the
air and which jiracticall}- is a microscopic seed. When
this falls on fertile ground it sprouts and becomes a white
downy mass, which is known as the hypha. This
downv mass later on assumes a color, which may be
cither grav, green, yellow or black, and is known under'
the i)opular title of mildew, which is in reality a fungus
or micro-organic growth of the vegetable t\-pe.
What mav be poistjnous to a human being is evi-
dently non-poisonous or neutral to a fungus, for fungi
THE GROWTH OF FrNGI O.V PAI.\T 285
can grow and do grow on practically all of the barium
precipitates, which are known to be highly poisonous.
A fungus needs both warmth and moisture for its
propagation, and so we will frequently find that on the
south side of a house at the seashore, where moisture will
collect and the temperature will be fairly uniform, fungi
will sprout on a painted surface and frequently destroy
the paint. This is more noticeable in the tropics than it
No. 71. Pemc'ilil'u Chustaceiim — No. 71, Asi'ikmii-i^^ Nk.ik
Pholomirrogniph x'kjo. a comniiiii — I'h.iioniu Ti.i;r,i]>h > 100,
green or cellar fungus (vhich groivs on old funitus fouiul un piiint.
many forms of puinl.
is in the North, and more noticeable in the European
countries than it is in America, for the humidity in the
United States is way below normal for more than half
of the j^ear whereas the humidity is fairly constant in
Europe and in the tropics. Some of these fungi are very
disagreeable, particularly the black types, which will
grow on the interior of houses, and which always, propa-
gate better in a cellar than they do in a garret, for light
has a tendency to kill them.
The fungi that are found on paint may be classified
into the following varieties:
_J
• .•1
286 CHEitlSTRY AXD TECHNOLOGY OF PAIXTS
1. Peniciiium Crustaceum tj^s, of which there are
many varieties, but all of which are greenish or olive
grayish.
2. Aspergillus Niger,
which is distinctly black
and ver>' tenacious. '
3. Rhizopus Nigricansy
which is brown and black,
and which appears gener-
ally in the Fall of the year.
4. Aspergillus Flavus, A^
which is yellow and orange, ^9
and which grows freely on n^. „ AsPEKonxos Niger -Pbot^
a putrid Stwl or near de- micrograph xioo, blact (ungus fre-
quently (ound on paint in cellars.
understood that the use of
to be recommended, for in
breweries, malt houses,
rooms which have swim-
ming pools, and cellars
which have been used for
storage, these fungi grow
at times, and it seems as
if there is nothing which
kills them. The best way
to get rid of them is to
wash the surface copiouslv
with soap and water and
then sjiray a mixture of car-
bolic acid and formaldehyde
and afterward bichloride of
mercury, but a man apply-
ing a material of this kind must use a mask and a
resi)irator.
caying vegetable matter.
It must be generally
fungicides is net always
THE GROWTH OF FUNGI ON PAINT 287
Many a complaint has reached a paint manufacturer
that his paint has turned black in spots under the eaves
of a roof or in a ground-
floor room, and the manu-
facturer on account of
ignorance has supplied
fresh paint free of charge,
or the painter has done
the work over again, when
as a matter of fact the
fault was due entirely to
fungus growth. It is well,
therefore, for the paint
chemist to familiarize him-
self with at least these
few fungi, as they are the
principal types which flourish on paint.
No. 76. CLADOSPOHIUU HERBAkUM —
Photomicrograph x6oo, a pale fungus
growing on damp walls.
ANALYSIS OF PAINT MATERIALS
Analysis of White Lead
Gravimetric Methods — Estimation as PbS04
Lead. — Dissolve i g. in dilute acetic acid, filter, wash
and weigh the insoluble residue. To the filtrate add lo
c.c. of dilute sulphuric acid (i:i) and evaporate on the
steam bath. Allow to cool, dilute cautiously to loo c.c,
add ID c.c. of alcohol and stir well. Filter on a Gooch or
alundum crucible, wash with water containing i p)er cent
of sulphuric acid and lo per cent of alcohol, and finally
with alcohol alone. Dry at iio° C.
Lead sulphate is appreciably soluble in concentrated
sulphuric acid and slightly soluble in water. It is practi-
cally insoluble, however, in i per cent sulphuric acid and
in alcohol. It is ver\' soluble in hot, concentrated am-
monium acetate solution.
Estimation as PbCr04
Treat i g. in a beaker with hot water and just suf-
ficient acetic acid to dissolve the white lead, using no
more than 5 c.c. of acetic acid in excess. Filter off from
the insoluble residue. Dilute to 100 c.c, heat to boiling
and add an excess of a neutral, saturated solution of
potassium dichromate solution. Allow to cool. Filter
on a Gooch or alundum crucible, wash and dr>' at 130° C.
Volumetric Methods — Estimation as Molvbdate
Dissolve 0.5 g. of white lead in 5 c.c. of concentrated
hydrochloric acid by boiling. Add 25 c.c of cold water
2SS
ANALYSIS OF PAINT MATERIALS 289
and proceed as indicated below, under "Standardization
of Ammonium Molybdate."
Lead is precipitated as PbMo04 by a standard solu-
tion of ammonium molybdate from hot solutions slightly
acid with acetic acid. The solutions required are:
(a) Ammonium molybdate — Dissolve 4.25 g. in i litre of water
(b) Tannic acid solution — Dissolve o.i g. in 20 c.c. of water
Standardization of Ammonium Molybdate. — Weigh off
about 0.2 g. pure lead foil in a small Erlenmeyer flask
and dissolve in 6 c.c. of nitric acid (1:2). Evaporate
the solution just to dryness. Treat the residue with
30 c.c. of water and 5 c.c. of concentrated sulphuric acid
and shake well. The precipitated lead sulphate is allowed
to settle, filtered and washed with dilute sulphuric acid
(1:10). Filter and precipitate are placed in an Erlen-
meyer flask and boiled with 10 c.c. of concentrated
hydrochloric acid until completely disintegrated. Then
add 15 c.c. more of concentrated hydrochloric acid, 25 c.c.
of cold water and neutralize with ammonia until slightly
alkaline to litmus paper. Reacidify with acetic acid.
Dilute to 200 c.c. with hot water and heat to boiling.
Titrate, using the tannic acid solution as outside indicator,
until a brown or yellow coloration is obtained with the
latter.
Precautions. — Titration must be carried out hot, at
about 90° C. If the solution should cool down in the
course of titration, reheat it. Here, as in the case of the
titration of zinc with potassium ferrocyanide, the scheme
of dividing the solution into two unequal parts may be
used.
To determine the excess of ammonium molybdate
necessary to affect the indicator, place in an Erlenmeyer
flask 25 c.c. of hydrochloric acid, neutralize until slightly
alkaline to litmus, then reacidify with acetic acid. Dilute
290 CHEMISTRY AND TECHNOLOGY OF PAINTS
to 200 c.c, heat to boiling, and add ammonium molybdate
drop by drop until the outside indicator is affected.
Antimony and bismuth do not affect the results
obtained by this method. Barium and strontium give
ver>^ low results, while calcium yields but slightly low
results. The alkaline earth sulphates tend to retard the
solution of the lead. This difficulty can be overcome by
thoroughly washing the lead sulphate and then boiling it
with sufficient ammonium acetate.
Carbon Dioxid and Combined Water. — i g. of white
lead is weighed off in a porcelain boat. -The latter is
then placed in a combustion tube and heated in a current
of dry air free from carbon dioxid. The water is col-
lected in calcium chloride tubes, and the carbon dioxid
in potash bulbs or soda lime tubes.
Carbon dioxid may be determined by evolution by
treating white lead with dilute nitric acid. Use a reflux
condenser in connection with the evolution flask and dr>'
the carbon dioxid by passing through calcium chloride
before absorbing in the potash bulbs or soda lime tubes.
Basic Lead Sulphate
Lead and Zinc {gravimetric), — Digest i g. for ten min-
utes in the cold with 20 c.c. of 10 per cent sulphuric acid.
Filter, keeping most of the residue in the beaker, and
wash twice by decantation with i per cent sulphuric acid.
The filtrate from the sulphuric acid teatment is re-
served for the determination of zinc which is carried out
by any of the methods outlined under ^*Zinc Oxid/*
Preferably precipitate as phosphate. Calculate the zinc
to ZnO.
Dissolve the residue in the beaker with hot concen-
trated slightly acid ammonium acetate solution pouring the
solution through the filter. Wash the latter with ammo-
• ANALYSIS OF PAINT MATERIALS 291
nium acetate and then with hot water. Dilute to 200 c.c,
add an excess of a neutral saturated solution of potassium
dichromate and bring to boiling. Allow to cool, and filter
on a Gooch or alundum crucible. Dry at 130° and weigh
as PbCrO;.
Lead (volumetric). — Treat 0.5 g. sample with 30 c.c. of
water and 5 c.c. of concentrated sulphuric acid, and
proceed as outlined under "Estimation as Molybdate."
Sulphates.^ — Dissolve 0.5 g. by boiling in a mixture of
25 c.c. water, 10 c.c. aqua ammonia and enough con-
centrated hydrochloric acid to give a slight excess. Dilute
to 200 c.c. and add a piece of pure thick aluminium foil
large enough to nearly cover the bottom of the beaker.
This should be kept at the bottom by means of a glass
rod. Boil gently until the lead is precipitated. When
the lead no longer adheres to the aluminium, the precipi-
tation may be considered complete. Filter and wash
wath hot water. A little sulphur-free bromine water is
added to the filtrate, the latter is boiled, and sulphates
determined by precipitation with barium chloride in
the ordinary way.
If desired the sulphates may be determined as indicated
under Analysis of "Zinc Lead."
Sulphur Dioxid. — Digest about 2 g. in the cold with
5 per cent sulphuric acid, and titrate with — iodine solu-
tion, using starch as indicator.
Analysis of Zinc Lead
Lead. — i g. of the material is heated on the steam
bath with 20 c.c. of hydrochloric acid (1:1) and 5 g.
of ammonium chloride. The solution is diluted to 250
c.c. with hot water and boiled. This treatment should
suffice to dissolve a pure zinc lead.
^ Holley, "Analysis of Paint and Varnish Products," 191 2, p. 104.
292 CHEMISTRY AND TECHNOLOGY OF PAINTS
The insoluble residue, if any, is filtered, weighed, and
examined for impurities. Neutralize the filtrate with
ammonia, reacidify slightly with hydrochloric acid, and
precipitate the lead with hydrogen sulphide.
Allow the precipitate to settle, filter oJ0F the liquid,
and wash the precipitate several times by decantation
with hydrogen sulphide water. The precipitate is finally
dissolved in hot, dilute nitric acid, treated with an excess
of sulphuric acid, and evaporated to SO3 fumes.
Allow to cool, dilute cautiously with 100 c.c. of cold
water, filter off the precipitated lead sulphate on a Gooch
crucible, wash several times with dilute sulphuric acid,
and finally once with alcohol. Dry at 130° C, and
weigh as PbS04.
Zinc. — The filtrate from the lead sulphide precipitate
is boiled to expel hydrogen sulphide, treated while hot
with a few drops of HNO3, then rendered slightly am-
moniacal, and any precipitate which is formed is filtered
off. The filtrate is then slightly acidified with acetic
acid, heated to boiling and a stream of sulphuretted
hydrogen passed in to precipitate the zinc. The latter
is filtered and washed with water containing a small
amount of acetic acid saturated with hydrogen sulphide,
using a Gooch or alundum crucible for filtering.
In filtering zinc sulphide, keep the crucible full of
liquid or wash water until the precipitate is completely
washed. Only then may the precipitate be allowed to
drain free from wash water.
The zinc sulphide is then dissolved in dilute hydro-
chloric acid, the sulphuretted hydrogen expelled by boiling,
and the zinc determined either volumetricallv bv the
ferro-cyanide method or gravimetrically by precipitation
with a slight excess of sodium carbonate, and ignition to
ox id.
ANALYSIS OF PAINT MATERIALS 293
Calcium and Magnesium. — The filtrate from the zinc
sulphide is evaporated to a small bulk and the calcium
determined by precipitating hot from a slightly ammoni-
acal solution with ammonium oxalate. Magnesium is
determined as usual.
Soluble S(Uts. — To determine the presence of zinc sul-
phate, I g. is digested with loo c.c. of water, filtered,
and the sulphate determined in the filtrate as usual, with
barium chloride.
Total Sulphates. — Dissolve 2^ g. of sodium car-
bonate in a beaker with 25 c.c. of water, add 0.5 g.
of the sample, boil gently for about ten minutes and
allow to stand for several hours. Dilute with hot water,
filter and wash until the filtrate is about 200 c.c.
Render the filtrate slightly acid with hydrochloric,
boil to expel carbon dioxid and precipitate the sulphate
with a slight excess of barium chloride solution.
Filter, wash and weigh as BaS04. Calculate the lat-
ter to PbS04.
Zinc Oxid
Insoluble. — Dissolve i g. in hot dilute acetic acid.
Filter, wash and weigh any insoluble residue. If the
latter is very small in quantity, it should be deter-
mined by dissolving a proportionately larger quantity of
zinc oxid.
Zinc. — Neutralize the filtrate with ammonia, then
make faintly acid with acetic acid, dilute to 300 c.c, and
precipitate with sulphuretted hydrogen. The solution
should be kept hot during the precipitation, and should
smell strongly of hydrogen sulphide at the end. Allow
the precipitate to settle, decant through an alundum or
Gooch crucible, keeping the crucible full of liquid during
the filtration, wash the precipitate in the beaker with a
294 CHEMISTRY AND TECHNOLOGY OF PAINTS
hot 2 per cent acetic acid solution saturated with hydro-
gen sulphide, finally transferring the zinc sulphide to the
crucible and allowing the last wash water to drain com-
pletely. The zinc sulphide is dissolved in dilute hydro-
chloric acid and boiled to expel H2S (test with lead acetate
paper held in the escaping vapors from the beaker or
flask to show the presence of hydrogen sulphide).
Gravimetric Methods for Zinc, — (a) Precipitation as Phosphate
The solution is rendered very faintly acid by almost
completely neutralizing wdth ammonia, diluted to 150 c.c.
and heated on the steam bath. Add to the solution on
the steam bath about ten times as much di-ammo-
nium phosphate ^ as zinc present. Heat for 15 minutes
longer. The crystalline zinc ammonium phosphate is
filtered through a Gooch or alundum crucible, washed
with hot I per cent ammonium phosphate solution until
free from chlorides, then with cold water and finally with
50 per cent alcohol. Dry at 120° C. for one hour and
weigh as ZnNH4P04.
(h) Precipitation as Carbonate
The zinc chloride solution is carefully neutralized in
the cold with sodium carbonate solution until a precipi-
tate begins to form. The solution is then heated to
boiling, and precipitation completed by adding a slight
excess of sodium carbonate (use phenolphthalein as indi-
cator). Ammonium salts must not be present. Filter on
a Gooch crucible, wash, ignite and weigh as ZnO.
Volumetric Method. - -YAnc is precipitated from hot
somewhat acid solutions by the addition of potassium
ferro-cyanide according to the following reaction:
^ Dissolve in cold water and add dilute ammonia until faint I v
pink with phenolphthalein.
ANALYSIS OF PAINT MATERIALS 295
3ZnCl2 + 2K4FeC6N6 = ZnsKzFeoCCN)^ + 6KC1 •
The end point is indicated by a solution of uranium ni-
trate as outside indicator. A brown coloration is produced
when a drop of the solution containing the excess of
potassium f errocyanide is added to a drop of uranium
nitrate solution on a spotting tile.
Solutions Potassium F errocyanide, — Dissolve 21.6 g.
of crystallized salt, K4FeC6N6-3H20 in cold water and
dilute to one liter. One c.c. of this solution is equivalent
to about 0.005 g. zinc.
Uranium nitrate 5% solution
Ammonium chloride 10 g. per liter
Standardization of Ferrocyanide. — Weigh out two or
three portions of 0.2 to 0.25 g. of pure ignited zinc oxid.
Dissolve in 10 c.c. of hydrochloric acid (1:2), add sodium
carbonate solution or ammonia until a slight permanent
precipitate is formed, redissolve the latter with one
or two drops of hydrochloric acid, add 6 c.c. of concen-
trated hydrochloric acid and 10 g. of ammonium chloride.
Dilute to 180 c.c, heat to 70° C. and titrate with ferro-
cyanide solution until the end point is reached. To
determine the end point rapidly divide the zinc solution
into two unequal parts. Titrate the smaller part run-
ning in the ferrocyanide solution i c.c. at a time. When
an excess has been added pour in the rest of the zinc so-
lution, run in i c.c. less than the quantity of potassium
ferrocyanide previously added, and finish the titration
drop by drop.
A blank must be deducted because of the excess of
potassium ferrocyanide required to develop the brown
coloration with uranium solution.
To determine the allowance, add 6 c.c. of concentrated
hydrochloric acid and 10 g. of ammonium chloride to 200
296 CHEMISTRY AND TECHNOLOGY OF PAINTS
c.c. of water in a beaker, heat to 70^ C, and add the
ferrocyanide solution until the brown coloration is obr
tained with the outside indicator. The correction should
be less than 0.5 c.c. Deduct this amount from all future
titrations.
Determination of Zinc. — To determine zinc in the
solution obtained by dissolving ZnS in hydrochloric add
and expelling hydrogen sulphide, neutralize with ammonia
or sodium carbonate, reacidify slightly with dilute hydro-
chloric acid, and proceed as outlined under '^ Standardiza-
tion of Ferrocyanide." The presence of a small amount
of lead does not interfere with the accuracy of the above
method.
Soluble Impurities. — Most zinc oxids are contami*
nated with small quantities of cadmium and traces of iron,
copper and lead. The cadmium ^ is best determined by
dissolving a relatively large amount, 25 to 50 g., of adnc
oxid in dilute sulphuric acid, filtering, diluting to 400 c.c.
and precipitating as sulphide in the presence of an
excess of about 5 c.c. of concentrated sulphuric acid in 100
c.c. of solution. Filter, wash, redissolve in sulphuric acid
and reprecipitate as sulphide. Dissolve into a crucible
with as small an amount of sulphuric acid as possible.
Evaporate cautiously and ignite to CdS04.
LiTHOPONE
Method I
Zinc Oxid. — Digest i g. with 100 c.c. of i per cent
acetic acid at room temperature for one half hour.
Filter, wash and weigh the insoluble. The loss in
weight represents the zinc oxid present.
* For electrolytic meth(xi of determining Cadmium, see E. F.
Smith's " P^lectro-Analvsis/'
ANALYSIS OF PAINT MATERIALS 297
Insoluble and Total Zinc. — Treat i g. in a 200 c.c.
beaker with 10 c.c. of concentrated hydrochloric acid,
mix, and add in small portions i g. of potassium chlorate
(this should be carried out under a hood); evaporate on
the steam bath to ^ the volume. Dilute with hot water,
add s c.c. of dilute sulphuric acid (1:10), boil, filter, and
weigh the insoluble. The latter is barium sulphate. The
zinc is determined in the filtrate by the methods outlined
under "Zinc Oxid."
Method II
Soluble Salts. — Treat 2 g. of lithopone with 100
c.c. of hot water. Digest for a few minutes and filter
on a Gooch crucible (test the filtrate for Ba, Zn and SO4).
Wash with hot water and finally once with alcohol.
Dry the crucible in the air oven at 100° C. and deter-
mine loss in weight. The latter is equal to the per-
centage of moisture present plus the water soluble
salts.
Zinc Oxid. — Digest for § hour, without warming, a i
g. sample with 100 c.c. of i per cent acetic acid. Filter,
wash, and determine the zinc in the filtrate gravimetrically
or volumetrically, as outlined under "Zinc Oxid.'' Cal-
culate to ZnO.
Zinc Sulphide. — Transfer the filter paper and residue
to a beaker, treat with dilute hydrochloric acid (1:4) and
boil to drive off H2S. Filter, wash with hot water, and
determine the zinc in the filtrate by the usual methods.
Report as ZnS.
Barium Sulphate. — The residue is dried, ignited,
treated with a few drops of concentrated sulphuric acid
in the crucible, again ignited and weighed as BaS04.
Test the latter for clay or silica. Should any be present,
treat the residue with hydrofluoric and sulphuric acids
298 CHEMISTRY AND TECHNOLOGY OF PAINTS
in a platinum crucible and evaporate to dryness. The
loss in weight represents silica.
Red Lead and Orange Mineral
Lead Peroxid {Metliod I). — Dissolve 0.5 g. in a beaker
with 30 c.c. of 2N nitric acid, heat to boiling to complete
solution. Add 25 c.c. N/5 oxalic acid, accurately meas-
ured from a pipette or burette, boil and titrate hot
with KMn04.
A blank containing the same quantities of nitric acid
and oxalic acid is also titrated against the permanganate.
The difference between the two titrations represents the
amount of Pb02 reduced by oxalic acid.
Pb304 + 4HNO3 = 2Pb (N03)2 + H2O+ HaPbO,
PbOa + H2C2O4 = PbO H- H2O+ 2CO2
Lead Peroxid {Metliod II). — Mix together in a small
beaker 1.2 g. of potassium iodide, 15 g. sodium acetate
and s c.c. of 50 per cent acetic acid. Weigh off 0.5 g. of
red lead in a 150 c.c. Erlenmeyer flask and add the above
mixture to it. Stir until the lead is completely dis-
solved. Dilute to 25 c.c, and titrate with N/io sodium
thiosulphate, using starch as indicator.
A little red lead, especially when it is not ver>'' fine in
texture, at first resists solution in the potassium iodide
mixture, but dissolves, on mixing, toward the end of the
titration. Proceed with the titration as soon as the lead is
in solution, so as to avoid loss of iodine by volatilization.
The reaction involved in the above method is
PbOo -f 4HI = Vhh + 2H2O 4- 12
The lead peroxid is reduced in the presence of an
excess of sodium acetate when treated with potassium
iodide in acetic acid solution.
ANALYSIS OF PAINT MATERIALS 299
Analysis of Iron Oxids
Moisture. — Heat 2 g. in the air oven at 105° C. for
two hours.
Loss on Ignition. — Ignite i g. in a porcelain crucible
to a red heat. The loss in weight consists of hygros-
copic moisture, water of combination, sometimes organic
matter, and carbon dioxid due to the presence of car-
bonates.
Insoluble. — Digest i g. of the oxid with 20 c.c. of
hydrochloric acid (1:1) on the hot plate for 15 minutes.
Filter, wash and weigh the insoluble residue. The
latter may be examined to determine the presence of
barytes, clay or silica.
Iron Oxid. — Weigh off from 0.3 to i.o g., depend-
ing upon the amount of iron oxid present, treat with
20 c.c. of hydrochloric acid (1:1) on the hot plate until
the residue is white, and while hot reduce with a strongly
acid stannous chloride solution until the iron solution
is colorless, using only one or two drops in excess. Wash
down the sides of the beaker and the cover glass with a
little water, add all at once 10 c.c. of a saturated solution
of mercury bichloride, stir, and wash the whole into a
large beaker containing 400 c.c. of cold distilled water to
which has been added 10 c.c. of preventive solution.
Titrate with N/io potassium permanganate to a faint
pink.
In the case of magnetic oxids and certain purple
oxids, solution is facilitated by the addition of i to 3 c.c.
of a 25 per cent stannous chloride solution. Should the
residue after digestion on the hot plate still show greenish
or black, filter, wash, and determine the iron in the soluble
portion as outlined below.
300 CHEMISTRY AND TECHNOLOGY OF PAINTS
To determine iron in the insoluble portion, fuse in a
porcelain crucible with five times its weight of potassium
bisulphate for about } hour. Cool, dissolve in water and
filter. Determine iron in the filtrate after reduction as
outlined below.
Stannous Chloride Solution. — Dissolve 50 g. of stan-
nous chloride in 100 c.c. of hydrochloric acid and dilute
to 1000 c.c. To preserve the solution, always keep a
few pieces of metallic tin- at the bottom of the bottle.
Preventive Solution:
Crystallized Manganese Sulphate 67 g.
Water 500 c.c
Syrupy Phosphoric Acid (Sp. Gr. 1.7). . .138 c.c.
Concentrated Sulphuric Acid 130 c.c.
Dissolve in the order named and dilute to i liter.
Analysis of Umbers and Siennas
To 0.5 to i.o g., depending upon the amount of iron
oxid present, in a casserole, add 20 c.c. of hydrochloric
acid (1:1) and 0.35 g. potassium chloride (or 0.25 g.
ammonium chloride), and evaporate to dryness on the
steam bath. Heat for 10 minutes longer to expel hydro-
chloric acid. Dissolve the soluble salts in about 25 c.c.
of hot water, filter and wash the insoluble residue. The
latter is dried, ignited and weighed, and reported as
insoluble or silicious matter. (When necessary analyze
this separately as indicated under "Analysis of Silica,
Asbestine or Clay'\)
To the filtrate, heated almost to boiling, there is
added 3.0 g. of sodium acetate for every 0.3 g. of iron
in solution, and 400 c.c. of boiling water. Heat to
incipient boiling. By this means the iron is quantita-
tix'cly precipitated as a basic acetate, while manganese
ANALYSIS OF PAINT MATERIALS 301
and other divalent metals of the group stay in solution.
The precipitate is allowed to settle, the solution decanted
off and filtered; the precipitate is washed several times
with hot water, dissolved in a small amount of hot dilute
hydrochloric acid, and either precipitated with ammonia
or determined volumetrically as under "Analysis of Iron
Oxids.'' The filtrate is evaporated to about half its
volume, treat-ed with an excess of bromine water, and
then boiled until the precipitated manganese dioxid be-
comes floccular. The precipitate is then filtered off,
washed, and ignited to Mn804.
Calcium and magnesium are determined in the fil-
trate in the usual way. When appreciable quantities of
these two elements are present, it is best to separate the
manganese by precipitation as sulphide.
To determine manganese as sulphide, heat the neutral
solution to boiling, add an excess of ammonia and am-
monium sulphide, and continue the boiling until the man-
ganese sulphide becomes a dirty green. Decant through
a Gooch crucible, using gentle suction, keeping the cru-
cible filled all the time. Wash the precipitate twice by
decantation with 5 per cent ammonium nitrate solution con-
taining a little anunonium sulphide, add to the crucible
and filter, allowing the crucible to drain. The filtrate
is acidified with dilute acetic acid boiled to expel hydro-
gen sulphide, and the calcium and magnesium deterr
mined as usual. The precipitated manganese sulphide
is dissolved in a little hot dilute hydrochloric acid,
evaporated to expel hydrogen sulphide, and precipitated
as carbonate or phosphate. In the first case the man-
ganese is ignited and weighed as Mn304.
Colorimetric Determination of Manganese.^ — Dissolve
^ Treadwell, Volume II, pages 127, 128. Marshall, Chem. News,
83, 76 (1904). Walters, Chem. News 84/239 (1904).
302 CHEMISTRY AND TECHNOLOGY OF PAINTS
0.5 g. of umber or sienna in about 10 c.c. of hydrochloric
acid (1:1) in a casserole, add an excess of nitric acid and
evaporate to dryness to drive oflF the hydrochloric acid.
Cool, add 20 c.c. of cold nitric acid (specific gravity 1.2)
filter and wash with the least quantity of cold water into
a 100 c.c. graduated flask. Make up to the mark.
Remove 10 c.c. by means of a pipette to a graduated
test tube, add 10 c.c. of silver nitrate ^ solution, and 2.5
c.c. of ammonium persulphate 2 solution, mix, and place the
tubes in water at 80 to 90° C. until bubbles of gas arise,
and remain at the top for a few seconds. Cool the test
tubes and compare against standard tubes made with
known amounts of manganese.
Mercury Vermilion
This pigment is very expensive and therefore quite
often adulterated. The possible adulterants are organic
lakes, orange lead chromes, red lead, and iron oxids, as
well as bar>les, silica or clay.
Its high specific gravity (8.2) and its insolubility in
alkalies, and in any one acid, distinguish it from all other
pigments of like color.
A pure vermilion can be volatilized completely on
heating, leaving no residue. On account of the ex-
tremely toxic properties of mercur>' vapors, such volatili-
zation should be carried out in a hood having a good
draft.
BarytcSj Silica or Clay. — Dissolve 2 g. in aqua regia,
or hydrochloric acid with a little potassium chlorate, and
after evaporating to dryness take up with boiling water
and a little hydrochloric acid. Filter and weigh the
residue.
^ i..:^8 g-AgnOs in 1000 c.c. of water.
* 20^0 solution.
ANALYSIS OF FAINT MATERIALS' 303
Lead. — Evaporate the filtrate from the above with an
excess of dilute sulphuric acid to SO3 fumes, and deter-
mine lead as PbSOi. (Calcium must be absent.)
Free mercury, free sulphur and iron may be identified
by dissolving the mercury vermilion in potassium mono-
sulphide (1:1), in which it dissolves readily. The solu-
tion is colorless after the iron sulphide has settled out.
Free mercury settles to the bottom of the dish as a gray
sediment.
Free sulphur is recognized by the yellow coloration of
the solution. It may also be detected in the usual way by
digesting with potassium hydroxid or extraction with
carbon disulphide (if present in crystalline form). The
quantitative determination is carried out by extracting with
soda solution and oxidation to sulphate.
For separating foreign adulterations such as bar>les,
clay, litharge, chrome red, brick dust, etc., potassium sul^
phide may be used to advantage. After filtering, wash
with dilute KOH solution and not with water, otherwise
the Brunner's salt decomposes with separation of black HgS.
The coal tar colors are identified by extraction with
alcohol; carmines by the drop test with anmionia on filter
paper.
For detecting arsenic sulphide, boil with caustic soda,
acidify with hydrochloric acid and introduce H2S gas into
the solution.
Analysis of Chrome Yellows and Oranges
Organic Matter. — Test with alcohol to determine pres-
ence of organic coloring matter.
Insoluble. — Boil i g. for about 5 minutes with 20 c.c.
of concentrated hydrochloric acid, adding i or 2 c.c. of
alcohol drop by drop. Dilute with about 100 c.c. of
boiling water. Boil a few minutes longer. Filter, wash
304 CHEMISTRY AND TECHNOLOGY OF PAINTS
with boiling water, and weigh the insoluble. Test the
latter for barium sulphate, clay or silica.
Lead. — Neutralize the filtrate with ammonia until a
slight permanent precipitate appears. Reacidify sligfatlyy
using an excess of not more than 1.5 c.c. of concentrated
hydrochloric acid in 100 c.c. of solution. Dilute to 200
c.c. Precipitate the lead with hydrogen sulphide. Fil-
ter, wash with H2S water, dissolve the PbS in hot dilute
nitric acid, boil to expel HsS, add 10 c.c. of dilute HsSOt
(1:1), evaporate to fumes of SOs and determine lead
gravimetrically or volumetrically as outlined under
"White Lead."
Chromium. — Evaporate the alcoholic filtrate- from the
PbS04 almost to dryness and mix with the filtrate from
PbS. The chromium is determined by precipitating hot
with a slight excess of ammonia. Filter, wash, ignite and
weigh as Cr208.
Zinc. — The filtrate from chromium hydroxid is ana-
lyzed for zinc by precipitating with hydrogen sulphide:
See "Zmc Oxid."
Chrome Greens
Preliminary Test. — Determine the presence of organic
coloring matter by extraction with alcohol.
Insohihle. — In a small evaporating dish heat i g.
sami)le at as low a temperature as possible until the blue
color is completely discharged. Transfer to a beaker, and
boil with 20 c.c. of concentrated hydrochloric acid and a
little alcohol to dissolve the soluble portion. Dilute with
hot water, boil, filter, wash, and weigh the insoluble por-
tion. Examine the latter for silica, clay or barytes.
Lead. — Determine in the filtrate after neutralizing
with ammonia and reacidifying slightly with hydro-
chloric acid as under "Chrome Yellows."
ANALYSIS OF PAINT MATERIALS 305
Ckromiumy Iron and Aluminium. — Boil the filtrate from
the lead sulphide to expel hydrogen sulphide, add a few
drops of nitric acid and about 2 g. of ammonium chloride.
Heat to boiling, and precipitate iron, aluminium, and
chromium as hydroxids with ammonia in slight excess.
Filter and wash the precipitates. Dissolve the mixed
hydroxids in a small amount of hot dilute hydrochloric
acid and dilute to 150 c.c. Heat to boiling and treat with
an excess of sodium hydroxid, and bromine water.
Filter and wash. Redissolve the ferric hydroxid in
dilute hydrochloric acid, and determine iron by the usual
methods.
The filtrate is acidified faintly with hydrochloric acid
and aluminium hydroxid precipitated with a slight excess
of ammonia.
The filtrate from aluminium hydroxid is carefully
acidified with acetic acid, and the chromium precipitated
by the addition of barium acetate to the hot solution.
Allow to stand for some time, and filter through a Gooch
or alundum crucible (using gentle suction). Wash with
alcohol, and dry in hot closet. Finally ignite at a dull
red heat by suspending the crucible inside a larger por-
celain crucible by means of an asbestos ring. If desired
the chromium present as alkali chromate may be reduced
to chromic salt by evaporating with hydrochloric acid
and alcohol. The chromium may then be precipitated
by ammonia and weighed after ignition as Cr203.
Calcium and Magnesium. — Determine as usual in the
filtrate from iron, aluminium and chromium hydroxids.
Sulphates. — Treat i g. as mentioned in the second
paragraph of this section. Determine sulphates as under
"Zinc Lead."
Nitrogen. — Determine by the Kjeldahl-Gunning
method.
3o6 chemistry and technology of* paints
Prussian Blue
Hygroscopic Moisture. — Determine on a i g. sample
by heating for 2 hours at 105*^ C.
Water of Composition. — Determine by difference after
the other constituents have been obtained.
Ferrocyanic Acid.^ — Treat 0.5 g. with 10 c.c. of nor-
mal, potassium hydroxid solution in a flask. Boil for 5
minutes, dilute with 50 c.c. of hot water, filter, and
wash the ferric hydroxid.
The filtrate containing a solution of potassium fer-
rocyanide is slightly acidified with sulphuric acid, 2 to 3
g. of ammonium persulphate are added, and the liquid
boiled from 20 to 30 minutes. Any blue color which
persists is removed by the addition of hydrochloric acid
and a little more persulphate.
The iron is precipitated with ammonia by the usual
method gravimetrically or volumetrically. Calculate as
FeCcNfl.
Cyanogen. — If desired, the total nitrogen in Prussian
blue may be determined by the Kjeldahl-Gunning method
as outlined in Bulletin 107, Bureau of Chemistrj^ U. S.
Dept. of Agriculture.
To determine the amount of Prussian blue, multiply
the total iron content by 3.03 or nitrogen content by 4.4.
The results thus obtained are fairly approximate. They
are not exact since the composition of Prussian blue is
variable. The pure Prussian blue should contain about
20 per cent of nitrogen and 30 per cent of iron, and less
than 7 per cent of moisture. The sulphuric acid used in
determining the nitrogen by the Kjeldahl-Gunning method
should not be blackened due to the presence of organic
adulterants.
* Ber. 1903, 36, 1929.
ANALYSIS OF PAINT MATERIALS 307
Iron. — To determine the total iron in Prussian blue,
ignite i g. gently until the blue color is completely dis-
charged. Dissolve the residue in lo c.c. of hydrochloric
acid (i : i), filter, make up to loo c.c. in a graduated flask.
Determine Fe208 in 50 c.c. in this solution (calculate to
metallic iron).
In the other 50 c.c. of the filtrate determine Fe203 +
AI2O3 by the usual methods. Calculate AI2O3 by difference.
Report as metallic aluminium.
Calcium. — Determine as usual in the filtrate from
Fe203 + AI2O3.
Alkali Metals. — Determine by the usual methods.
Analysis of Ultramarine
The ultramarine is finely powdered and dried at 100°.
2 to 10 g. are weighed off, digested with water, filtered,
the filtrate diluted to 500 c.c, and 100 c.c. taken for each
of the following determinations.
(a) Na2S203 — determine with iodine solution and
starch. Calculate to Na2S203 + Ag.
(ft) Na2S04 — determine by precipitating with barium
chloride in acid solution.
{c) NaCl — determine by precipitating with AgNOs
(NaCl is rarely present in ultramarine).
10 to 20 grams of ultramarine are washed two or three
times by decantation (to obtain a clear filtrate, alcohol is
added). Evaporate almost to dryness with a dilute solu-
tion of sodium sulphite ^ on the water bath. Wash until
a test of the ultramarine moistened with water and fil-
tered gives no trace of turbidity with barium chloride.
^ In order to remove free S, for CS2 extracts only 40 to 60%
of the same.
3o8 CHEMISTRY A^D TECIIXOLOCY OF PAIXTS
The ultramarine dried at 130 to 140° is again powdered
and placed hot into a glass stoppered flask.
II
Estimation of silicic acid, silica, clay and total sulphur.
I g. of the dried substance is weighed into a porcelain
dish, stirred up with water and treated with i.to 2 c.c. of
bromine. If it is partially dissolved (as shown by the yellow
coloration of the liquid) 15 to 20 c.c. of nitric acid are added
and the whole evaporated to dryness on the water bath.
Take up with water, add 20 c.c. of hydrochloric acid
and evaporate again (to remove nitric acid which would
increase the BaS04 precipitate, and to render silicic acid
insoluble). Treat with hydrochloric acid, digest warm
for a few hours, dilute with water and filter. On the
filter are left silicic acid and sand.
To determine total sulphur, the filtrate is heated to
boiling and precipitated with barium chloride.
Ill
Estimation of alumina and of soda.
I g. of ultramarine, washed and dried as in number
I, is carefullv mixed with water and treated with an ex-
cess of hydrochloric acid. After standing for a while it
is heated until the solution settles clear. It is then fil-
tered, leaving sulphur, sand and silicic acid undissolved.
The residue is weighed after ignition. The filtrate is
evaj^orated to dryness, the residue moistened with water
and hydrocloric acid and again dried. Take up with
hydrochloric acid, dilute with water after standing for
some time and filter. On the filter is left silicic acid,
which, added to the residue obtained in the first filtra-
tion, gives the content of total silicic acid and sand. The
filtrate is evaporated to dryness to remove excess hydro-
ANALYSIS OF PAINT MATERIALS 309
chloric acid. The residue is dissolved in water, precipi-
tated with ammonia and the whole thoroughly dried in
the water bath. (This facilitates complete washing of
the alumina.) /
Take up the residue with hot water, add a few drops
of ammonia, heat and filter. Alumina on the filter is
determined and weighed.
For determining soda, the filtrate is treated with sul-
phuric acid and a little fuming nitric acid and evaporated
to dryness. The residue is strongly ignited and the
Na2S04 calculated to Na.
Black Pigments
(Carbon Black, Lampblack, Vine Black, Bone Black)
Moisture. — Determine on a 2 g. sample by heating
for two hours at 105° C.
Volatile, — Heat for 10 minutes over a Bunsen flame
in a well-covered porcelain crucible.
Ash. — Determine on a i g. sample, ignite over a
Bunsen burner with free access of air. When the ash is
large in quantity, cool, moisten with a solution of ammo-
nium carbonate and ignite again gently.
Soluble and Insoluble Ash. — Treat the ash obtained
by the above procedure with 5 to 10 c.c. of dilute hydro-
chloric acid, heat, filter, wash and weigh the insoluble
portion. Calculate the percentage of acid-soluble ash
from the total ash and the acid-insoluble ash.
Certain blacks are sometimes adulterated with Prus-
sian blue. To detect the latter, boil with dilute caustic
soda, filter, acidify the filtrate with dilute hydrochloric
acid, and add a mixture of ferric chloride and ferrous
sulphate. The formation of a blue precipitate indicates
the presence of Prussian blue.
3io chemistry ajftd technology of paints
Graphite
Heat I g. of the finely powdered graphite to a dull
red heat and calculate the loss in weight as water. The
dried substance is intimately mixed with 3 g. of a mixture
of equivalent parts of K2CO3 and NasCOs and placed in a
crucible, i g. of KOH or NaOH is sprinkled over the
surface of this mixture and the whole heated slowly to
redness. The mass fuses, swells and forms a crust on b^,
which must be broken with a stout platinum wire.
After fusing for one half hour, the melt is cooled,
heated with water for J hour almost to boiling, filtered,
washed well and the liquids set aside. The insoluble is
dried, placed in a dish, the filter ash added and about 3 g.
of HCl (specific gravity 1.18) poured in. After several
minutes a slight gelatinization sets in due to the decom-
position of the small residue of alkali silicate. The addi-
tion of a little more hydrochloric acid brings the silicic
acid into solution. After digestion for one hour, dilute
with water, filter and wash out. The residue on the fil-
ter is pure carbon, which, after drying and gentle ignition,
is weighed. The acid filtrate is united with the alkaline
one obtained above, more HCI added until weakly acid,
evaporated to drj^ness, and silicic acid, alumina and iron
oxid determined as usual.
Blanc Fixe
Water Soluble Salts, — Owing to the variety of methods
emT)loycd in the technical production of blanc fixe, a
prcliminar}' qualitative examination of the material is
always essential before proceeding with the quantitative
analysis.
Digest about 5 g. with 150 c.c. of hot water and
filter. Examine the filtrate to detect the presence of
ANALYSIS OF PAINT MATERIALS 311
water soluble salts. Determine the amount of water
soluble salts, by difference, on a i g. sample.
Acid Soluble. — Digest r g. of blanc fixe with hot water,
wash by decantation and filter, keeping as much of the
residue as possible in the beaker. Discard the filtrate
and treat the residue in the beaker with about 25 c.c. of
hot dilute HCl (1:3); filter through the filter paper used
above, wash and ignite. Add i drop of nitric and 2 drops
of sulphuric acid, evaporate, ignite again and weigh. Cal-
culate % acid soluble from loss in weight, % water soluble
and % moisture.
BaS04. — Proceed as outlined below under barytes
(fusion in platinum with Na2C03) to determine barium
sulphate and silica (Page 314).
Iron. — Determine colorimetrically.
Silica. — To determine qualitatively ^ whether a sample
of blanc &xe is free from silica or clay, heat about 0.5 g.
with 10 to 15 c.c. of concentrated sulphuric acid. A pure
blanc fixe or barytes dissolves completely. Silicious matter
remains undissolved. Determine the amount of silicious
matter on a i. g. sample by evaporating with a few c.c.
of hydrofluoric acid and several drops of sulphuric acid.
Analysis of Whiting
Carbon Dioxid. — Determined as outlined under " White
Lead.''
Calcium. — Determined by the usual methods.
Gypsum or Calcium Sitlphate
Calcium and Sulphates. — Determine by the usual
methods.
Moisture. — Dry 2 g. in a vacuum dessicator over
sulphuric acid to constant weight.
^ Method developed in the laboratory of Toch Brothers.
312 CHEMISTRY AND TECHNOLOGY OF PAINTS
Combined H2O and Moisture. — Heat i g. in a covered
porcelain crucible on an asbestos plate for 15 minutes,
then heat the bottom of the crucible to dull redness for
10 minutes over a Bunsen burner, remove the cover and
heat for 30 minutes at a slightly lower temperature.
Cool and weigh rapidly.
Silica, Asbestine, Clay (Barytes)
Hygroscopic Moisture. — Determine on a 2 g. sample
by heating for i hour at 105° C.
Loss on Ignition. — Determine on a i g. sample. This
is largely water of composition, unless carbonates are
present.
Complete Analysis. — Mix 0.5 g. in a platinum crucible
intimately with about 5 g. of anhydrous sodium car-
bonate. Add a thin layer of the latter on top, cover
the crucible and heat gently over a Tirrill or Tech burner
for a short time. Raise the temperature gradually to
the full heat of the burner. Finally heat for a short
time over the blast lamp. Allow to cool, then heat the
lower part of the crucible to dull redness, and cool again.
Add a little water, heat carefully to boiling and the melt
will readily separate from the crucible. Place the melt
in an evaporating dish; wash the crucible with a little
hot water, and add to the dish. If barytes, or blanc fixe
is present, the melt is digested with hot water until
com])letely disintegrated, the barium carbonate is fil-
tered ofT and washed, and the barium determined as
outlined under barium carbonate. The filtrate is then
treated in a large covered beaker with concentrated
hydrochloric acid. After a certain amount of acid has
been added, the silicic acid separates out as a gelatinous
mass, which has to be broken up in order to obtain inti-
mate admixture with the acid. After an excess of acid
ANALYSIS OF PAINT MATERIALS 313
has been added, the solution is heated to boiling, trans-
ferred to a porcelain or platinum dish and evaporated to
dryness.
It is essential that dehydration of the silica be carried
out twice ^ at the temperature of the steam bath and that
the insoluble silica be filtered off before evaporating the
second time.
Filter, wash, combine the insoluble residues from the
two dehydrations, ignite in a platinum crucible and weigh.
Drive off Si02 with a few c.c. of HF and several drops of
H2SO4. Ignite and reweigh. The loss in weight is silica.
Iron and Aluminium Oxids. — Treat the filtrate from
the silicic acid with a few drops of concentrated nitric
acid and lo to 20 c.c. of a cold saturated solution of
ammonium chloride. Heat to boiling and precipitate
with a slight excess of ammonia. Allow the precipitate
to settle, filter off the clear liquid and wash twice by
decantation with hot water. Redissolve the ferric and
aluminium hydroxids by running hot dilute hydrochloric
acid through the filter paper into the beaker containing
the major portion of the precipitate. Reprecipitate with
ammonia, as before, filter, wash and ignite wet in the
platinum crucible containing the residue obtained after
Si02 was volatilized with HF and H2SO4. Weigh as
FeaOs + AI2O3.
For the determination of iron in the mixed oxids, sae
Treadwell and Hall, Vol. II, p. 109.
Calcium. — Evaporate the filtrates from the ferric and
aluminium hydroxids to a small volume. Heat to boil-
ing and precipitate with a boiling solution of ammonium
oxalate. Allow to stand for several hours. Filter and
wash. Puncture the filter paper with a glass rod, wash the
precipitate into a beaker with a stream of water from the
^ Hillebrand, "Analysis of Silicate and Carbonate Rocks."
314 CHEMISTRY AND TECHNOLOGY OF PAINTS
wash bottle, and pass 20 c.c. of hot .dilute sulphuric acid
(1:1) over and through the filter paper. . Heat to 90® C.
and titrate with N/io KMn04.
Magnesium. — Evaporate the filtrate from the calcium
oxalate to dryness, and ignite in a porcelain dish. Moisten
the residue with a little concentrated hydrochloric acid
and dissolve in hot water. Filter and determine mag-
nesium in the filtrate. Heat to boiling and treat with an
excess of sodium or anunonium phosphate. Add an
amount of 10 per cent ammonia equal to | of the volume of
solution. AUow to cool and set aside for a few hours.
Filter through an alundum crucible, wash with 2.5 per cent
ammonia, dry, ignite slowly at first and finally strongly
until the precipitate is white. Weigh as MgiPjOi.
Alkalies. — See J. Lawrence Smith (Bulletin 422, U.
S. Geologic Survey).
Barytes
Make a preliminary test for lead compounds. In
the absence of the latter weigh ofiF i g. sample and mix
with 5 g. anhydrous sodium carbonate in a platinum
crucible. Fuse over the blast lamp for a half hour, occa-
sionally imparting a rotary motion to the crucible to
insure thorough reaction. Allow to cool, then heat the
lower part of the crucible to dull redness, and cool again.
Add a little water, bring carefully to boil, and the melt
will readily separate from the crucible. Place in an
evaporating dish, add 100 c.c. of water, and digest on
the steam bath until com])letely disintegrated. Filter
and wash the insoluble residue (BaCOs) until free from
soluble salts. Dissolve the BaCOa with 25 c.c. of hydro-
chloric acid (1:3), catching the filtrate and passing it
through the filter to insure complete solution of the
barium carbonate. Boil to expel carbon dioxid, neu-
^i^ALYSIS OF PAINT MATERIALS 315
tralize the filtrate with ammonia, reacidify with a few
drops of hydrochloric acid, heat to boiling, and precipi-
tate with dilute sulphuric acid. Filter and wash on a
Gooch crucible, dry at 130° C. and report as BaS04.
In the presence of lead, first extract the barytes with
hot concentrated ammoniimi acetate solution before
proceeding with the sodium carbonate fusion, since the
presence of metallic lead in the fusion will ruin the
platinum crucible.
Iron. — Determine colorimetrically .
Clay and Silica. — Acidify the filtrate from the barium
carbonate with hydrochloric acid, evaporate to dryness
on the steam bath, heat for 20 minutes longer on the
steam bath, and extract with hot water and a little
hydrochloric acid. Filter, wash and weigh the insoluble
Si02. Determine alumina in the filtrate from Si02 as
usual. See also determination of silica in blanc fixe
(p. 311).
In reporting the presence of silica and alumina, it
must be remembered that the reagents used in the above
determination, sodium carbonate and ammonia, almost
always contain appreciable quantities of silica and alu-
mina. Especially is this true of aqua ammonia, except
when kept in bottles lined with ceresin or paraffin wax.
Analysis of Barium Carbonate
Water Soluble Sails. — Determine by difference in a i
g. sample, treat with hot water, filter, wash, and weigh
the insoluble.
Insoluble. — - Dissolve about 10 g. in dilute hydro-
chloric acid. Heat to boiling, filter, wash and weigh
the insoluble residue. The latter is generally silicious,
but should be examined to determine the presence of
barium.
3l6 CHEMISTRY AND TECHNOLOGY OF PAINTS
Barium. — Dissolve 0.5 g. in dilute hydrochloric acid,
neutralize with ammonia, then reacidify faintly with
hydrochloric acid. Dilute to 100 ex., heat to boiling,
and precipitate with hot dilute sulphuric acid. Filter on
a Gooch crucible, wash, and dry at 130° C. Calculate
BaS04 to BaCOs. For the separation of barium, cal-
cium, and strontium from each other, see Treadwell and
Hall, Anal. Chem., Vol. II, p. 79.
Carbon Dioxid. — Determine by evolution as outlined
under "White Lead."
Iron.^ — Treat 2 g. in a beaker with 15 c.c. of water
and sufficient nitric acid to dissolve the barium carbonate.
Boil for several minutes to expel carbon dioxid and to
convert all the iron to the ferric state. Filter and
wash the residue. Cool the filtrate, neutralize with
ammonia and acidify faintly with nitric acid.
Wash the contents of the beaker into a 100 c.c.
Nessler cylinder, add 15 c.c. of dilute ammonium thio-
cyanate (1:20) and dilute to the mark. The depth of the
blood red color developed is a measure of the amount of
iron present. Compare with a blank made as follows:
Prepare a standard solution of ferric ammonium sul-
phate by dissolving 0.7022 g. of ferrous ammonium sul-
phate in water. Acidify with sulphuric acid, heat to
boiling and oxidize the iron by the addition of a solu-
tion of potassium permanganate. Only the faintest
excess of permanganate should be added. The faint pink
tinge due to the latter soon disappears. The solution is
cooled and diluted to i liter. One c.c. of this solution
is equivalent to o.oooi g. of iron.
Into a 100 c.c. Nessler cylinder add about the same
amount of nitric acid as was used to dissolve the barium
^ Modified Thompson & SchacfTcr method. J. Ind. Eng. Chem.
1912, 659.
ANALYSIS OF PAINT MATERIALS 317
carbonate, and 15 c.c. of ammonium thiocyanate solution.
Dilute to 100 c.c. and add the standard ferric ammonium
sulphate solution, drop by drop, until the color exactly
matches that developed in the sample being tested.
One c.c. of the solution is equivalent to o.oi per cent
iron when a i g. sample is used. Not more than
2 or 3 c.c. of the standard should be required to equal
the color; otherwise, the color becomes too deep for
comparison.
Sulphur . — For colorimetric determination see Tread-
well & Hall, Vol. II, pages 354-7.
Chlorine. — Determine in the water soluble portion
(acidified with nitric acid) by precipitating hot in the
presence of a slight excess of silver nitrate, filter on a
Gooch or aluridum crucible, wash, and weigh the insoluble
AgCl after drying at 130° C.
Analysis of Mixed White Paints
I. By use of Acetic Acid
Treat i g. of the mixed white pigment with 22 c.c. of
water and 10 c.c. of glacial acetic acid. Boil, filter, and
wash with water. The filtrate is heated to boiling, and
precipitated with hydrogen sulphide. Filter off the lead
and zinc sulphides, dissolve in hot dilute nitric acid, and
determine lead and zinc as usual. Calculate the lead to
white lead, and zinc to oxid. The filtrate from lead and
zinc sulphides is tested for Ba, Ca, and Mg. Determine
and calculate to carbonates.
To the residue from the acetic acid treatment add
10 c.c. of water, 10 c.c. of strong hydrochloric acid, and
5 g. ammonium chloride. Heat on steam bath for 5
minutes, dilute with boiling water to 400 c.c, boil, filter,
wash, ignite and weigh the insoluble. Examine for
silica, clay, barytes or asbestine.
3i8 CHEMISTRY AND TECHNOLOGY OF PAINTS
Precipitate the lead in the filtrate with hydrogen sul-
phide, filter and wash. Dissolve in hot dilute nitric acid,
and determine as usual. Report as PbS04. The fil-
trate is boiled to expel hydrogen sulphide, a few drops
of nitric acid, ammonium chloride, and anmtionia in excess
are added to precipitate iron and aluminium. Calcium
is determined in the filtrate as usual. Report as CaSOf.
II. By G. W. Thompson, {Jour. Soc. Chem, Ind. i§, 4J2)
"The qualitative examination for the elements pres-
ent may be determined as follows: Effervescence with
concentrated hydrochloric acid indicates carbonic acid,
sulphuretted hydrogen if zinc sulphide is present, or sul-
phurous acid if lead sulphite is present. These latter
two may be recognized by their odors. Boil a portion
of the paint with acid ammonium acetate and test a
portion of the filtrate for sulphuric acid with barium
chloride. Test another portion of the same solution
with sulphuric acid in excess for lead and test filtrate
for zinc by making alkaUne with ammonia, and adding
ammonium sulphide. Test another portion of the am-
monium acetate solution for lime by making alkaline
with ammonia, adding ammonium sulphide, filtering and
adding ammonium oxalate to filtrate. The portion
insoluble in ammonium acetate, in the absence of sul-
phite of zinc and sulphate of lead may be barytes, China
clay, or silica. The qualitative examination of this
residue is best combined with quantitative examination
given further on.''
'*The oxids and elements, the presence of which is
usually possible in a white paint, are: carbonic acid,
water (combined), sulphuric acid, sulphurous acid, sulphur
(combined as sulphide), silica, barium oxid, calcium
oxid, zinc oxid, and zinc combined as sulphide, lead
oxid, aluminium oxid."
ANALYSIS OF PAINT MATERIALS . 319
"In the absence of sulphuric acid^ the lead soluble in
acetic acid may be directly calculated to white lead."
"Sulphuric acid may exist in two conditions, in one
it is soluble in ammonium acetate, and in the other, as
in barytes, it is insoluble in ammonium acetate. That
soluble in ammonium acetate may be determined by
precipitating with barium chloride in that solution.
Sulphuric acid in barytes is best calculated from the
barium present, and determined as described later on.
Sulphurous acid may be determined by oxidation to sul-
phuric acid, or its determination may be based on the
insolubility of lead sulphite in ammonium acetate. For
instance, one portion of the sample is oxidized with
nitric acid and the total lead determined. Another
portion is treated directly with ammonium acetate, and
the lead soluble in that menstruum determined. The
diflFerence between the two determinations is the lead
present as sulphite, from which we may calculate the
sulphurous acid present. Sulphur as sulphide is always
present as zinc sulphide, which is never used in the
presence of lead compounds. It may be determined by
oxidation with bromine water and precipitation with
barium chloride, or by determining the zinc insoluble
in ammonium acetate. Silica may be determined by
treating the matter insoluble in ammonium acetate with
hydrofluoric acid and sulphuric acid. The loss on
ignition is silica, or it may be determined by fusing the
residue in the regular way. Barium oxid is determined
by precipitation with sulphuric acid from hydrochloric
acid solution of that part of fused residue insoluble in
water."
Rapid Methods for White Pigments
"Sample i is a mixture of barytes, white lead, and
zinc oxid.
320 CHEMISTRY AND TECHNOLOGY OF PAINTS
"Two i-gram portions are weighed out. One is
dissolved in acetic acid and filtered, the insoluble matter
ignited and weighed as barytes, the lead in the soluble
portion precipitated with dichromate of potash, weighed
in Gooch crucible as chromate, and calculated to white
lead.
"The other portion is dissolved in dilute nitric acid,
sulphuric acid added in excess, evaporation carried to
fumes, water added, the zinc sulphate solution filtered
from barytes and lead sulphate and precipitated directly
as carbonate, filtered, ignited, and weighed as oxid.
"Sample 2 is a mixture of barytes and so-called sub-
limed white lead.
"Weigh out three i-gram portions. In one determine
zinc oxid as in Case i. Treat a second portion with
boiling acetic acid, filter, determine lead in filtrate and
calculate to lead oxid. Treat third portion by boiling
with acid ammonium acetate, filter, ignite, and weigh
residue as barj^tes, determine total lead in filtrate, deduct
from it the lead as oxid, and calculate the remainder
to sulphate. Sublimed lead contains no hydrate of lead,
and its relative whiteness is probably due to the oxid of
lead being combined with the sulphate as basic sulphate.
Its analysis should be reported in terms of sulphate of
lead, oxid of lead, and oxid of zinc.
"Sample 3 is a mixture of barytes, sublimed lead, and
white lead.
"Determine barj'tes, zinc oxid, lead soluble in acetic
acid and in ammonium acetate, as in Case 2; also deter-
mine carbonic acid, which calculate to white lead, deduct
lead in white lead from the lead soluble in acetic acid, and
calculate the remainder to lead oxid.
"Sample 4 is a mixture of barytes, white lead, and
carbonate of lime.
ANALYSIS OF PAINT MATERIALS 321
"Determine barj^tes and lead soluble in acetic acid
(white lead) as in Case i. In filtrate from lead chromate
precipitate lime as oxalate, weigh as sulphate, and cal-
culate to carbonate. Chromic acid does not interfere
with the precipitation of lime as oxalate from acetic acid
solution.
'^Sample 5 is a mixture of barytes, white lead, zinc
oxid, and carbonate of lime.
"Determine barytes and white lead as in Case i.
Dissolve another portion in acetic acid, filter and pass
sulphuretted hydrogen through the boiling solution, filter,
and precipitate lime in filtrate as oxalate; dissolve mixed
sulphides of lead and zinc in dilute nitric acid, evaporate
to fumes with sulphuric acid, separate, and determine
zinc oxid as in Case i.
"Sample 6 is a mixture of barytes, white lead, sub-
limed lead, and carbonate of lime.
"Determine barytes, lead soluble in acetic acid and in
ammonium acetate, as in Case 2, lime and zinc oxid, as
in Case 5, and carbonic acid. Calculate lime to car-
bonate of lime, deduct carbonic acid in it from total
carbonic acid, calculate the remainder of it to white lead,
deduct lead in white lead from lead soluble in acetic acid,
and calculate the remainder to oxid of lead.
"Sample 7 contains sulphate of lime.
"Analyses of paints containing sulphate of lime
present peculiar difficulties from its proneness to give
up sulphuric acid to lead oxid if white lead is present.
Sulphate of lime and white lead boiled in water are more
or less mutually decomposed with the formation of sul-
phate of lead and carbonate of lime. A method for the
determination of sulphate of lime is by prolonged washing
with water with slight suction in a weighed Gooch
crucible. This is exceedingly tedious, but thoroughly
52J CHEMISTRY AXD TECHSOLOGY OF PAJSTS
accurate. A reservpir containing water may be placed
above the crucible, and the water allowed to drop slowly
into it. This may take one or two days to bring the
Siunple to constant weight, during which time several
liters of water will have passed through the crucible.
Another method for separating the sulphate of lime is
by treatment in a weighed Gooch crucible with a mixture
of nine jxirts of 95 per cent alcohol and one part of
glacial acetic acid. Acetates of lead, zinc, and lime being
sohible in this mixture, the residue contains all the sul-
phate of lime and any sulphate of lead and barytes which
may be present. Determine the lead and lime as in
s;\mple 4, and calculate to sulphates. Sulphate of lime
should be fully hydrated in paints. To determine this,
obtain loss on ignition; deduct carbonic acid and water
in other constituents; the remainder should agree fairly
well with the calculated water in the hydrated sulphate
of lime, if it is fully hydrated. If, after washing a small
portion of the sample with water, the residue shows no
sulphuric acid soluble in ammonium acetate, the sulphate
oi lime may bo obtained by determining the sulphuric
;uid soluble in ammonium acetate and calculating to
sulphate oi lime. The dilTiculty is in determining the sul-
pluilc of lime in the presence, or possible presence, of
sulphate oi lead. To illustrate the analysis of sample of
w hilc paint contaiuing sulphate of lime and the difliculty
atlciuling thereon, wc would mention a sample containing
suhlimed lead, while lead, carbonate of lime, and sulphate
o\ lime. In such a samj^le we would determine the
lead, lime, sulphuric acid, carbonic acid, loss on ignition,
the portion soluble in water, and the lime or sulphuric
acid in that portion, calculating to sulphate of lime.
Deduct the lime in the sulphate of lime from the total
lime, and calculate the remainder to carbonate of lime;
ANALYSIS OF PAINT MATERIALS 323
deduct the carbonic acid in the carbonate of lime from
the total carbonic acid, and calculate the remainder to
white lead; deduct the sulphuric acid in the sulphate of
lime from the total sulphuric acid, and calculate the
remainder to sulphate of lead. The lead unaccounted for
as sulphate or white lead is present as oxid of lead.
Deduct the carbonic acid and water in the carbonate of
lime and white lead from the loss on ignition, the re-
mainder being the water of hydration of the sulphate of
lime.
*^ Sample 8 contains as insoluble matter, barytes,
China clay and silica.
'* After igniting and weighing the insoluble matter,
carbonate of soda is added to it, and the mixture fused.
The fused mass is treated with water, and the insoluble
portion filtered off and washed. This insoluble portion
is dissolved in dilute hydrochloric acid, and the barium
present precipitated with sulphuric acid in excess. The
barium sulphate is filtered out, ignited, weighed, and if
this weight does not differ materially — say by 2 per
cent, — from the weight of the total insoluble matter,
the total insoluble matter is reported as barytes. If the
difference is greater than this, add the filtrate from the
barium sulphate precipitate to the water-soluble portion
of fusion. Evaporate and determine the silica and the
alumina in the regular way. Calculate the alumina to
China clay on the arbitrary formula 2SiOi. AI2O3. 2H2O,
and deduct the silica in it from the total silica, reporting
the latter in a free state. It is to be borne in mind that
China clay gives a loss of about 13 per cent on ignition,
which must be allowed for. China clay is but slightly
used in white paints as compared with barytes and
silica."
"Sample 9 contains sulphide of zinc.
324 CHEMISTRY AND TECHNOLOGY OF PAINTS
'^Samples of this character are usually mixtures in
var>'ing proportions of barium sulphate, sulphide of zinc,
and oxid of zinc. Determine barytes as matter insolu-
ble in nitric acid, the total zinc as in Case i, and the zinc
soluble in acetic acid, which is oxid of zinc. Calculate
the zinc insoluble in acetic acid to sulphide."
"Sample lo contains sulphite of lead.
"This is of rare occurrence. Sulphite of lead is in-
soluble in ammonium acetate, and may be filtered out
and weighed as such. It is apt on exposure to the air in
the moist state to become oxidized to sulphate of lead.
"There are certain positions which the chemist must
take in reporting analyses of white paints:
^^ First. White lead is not uniformly of the composition
usually given as theoretical 2PbC0j- Pb(OH)i, but in
reporting we must accept this as the basis of calculating
results, unless it is demonstrated that the composition of
the white lead is very abnormal.
^^ Second. In reporting oxid of lead present this
should not be done except in the presence of sulphate of
lead, and if white lead is present, then only where the
oxid is more than i per cent; otherwise calculate all
the lead soluble in acetic acid to white lead.
" ThiriL China clav is to be calculated to the arbi-
trar>' formula given.
"In outlining the above methods we have in mind
many sami)les that we have analyzed, and the combinations
we have chosen are those we have actually found present."
Analysis of Paints
Separation -of Pigment from Vehicle. — The can of paint
is weighed off and if free from water, heated on the steam
bath for 1 5 to 30 minutes. Owing to the marked decrease
in the s])ecific gravity and the viscosity of the i)aint
ANALYSIS OF PAINT MATERIALS 325
vehicle at the higher temperature, the pigment generally
settles to the bottom very quickly.
In the case of paints which show the presence of
water, it is best to allow the pigment to settle out in
the cold in order to avoid any saponifying action which
the pigment might exert on the vehicle. The clear
liquid is then drawn off as far as possible and set
aside for analysis. The can is carefully wiped and
weighed again.
About 25 g. of the residue in the can are weighed
into a tall weighing tube. A mixture of benzol and
alcohol 1:1 is added and the contents carefully stirred
up with a glass rod. Another tube containing a similar
weighed quantity of the same material is balanced to
within 0.1 of a gram against the first tube, after adding
the solvent and stirring.
The two are then placed in the opposite receivers of a
centrifuge and whirled at a moderate or high speed,
(depending upon the facility with which the pigment set-
tles out) for about five or ten minutes. The clear liquid
is then drawn off, the tubes balanced, and after the
addition of fresh solvent, stirred and again centrifuged.
This is continued until no more of the vehicle can be
extracted.
The tubes are then placed in an air oven first at 80°
C. and then at 100° C. until dry. From the weights of
the tubes before and after extraction, the weight of paint
extracted, and the weights of the can with and without
the supernatant liquid, the percentage of vehicle and
pigment can be calculated.
There is generally left with the extracted pigment a
small percentage of unextracted matter (probably soaps
resulting from the interaction of pigment and vehicle,
or linoxyn), for which allowance must be made.
326 CHEMISTRY AND TECHNOLOGY OF PAINTS
The extracted pigment is analyzed as outlined in the
chapter on "Methods of Analysis of Pigments."
Determination of Volatile Matter.^ — Weigh oflF into a
round bottomed flask, 50 to 75 g. of the ready mixed
paint. Connect with a condenser by means of a steam
trap. Pass live steam through until no more of the
volatile oil comes over. Allow the distillate to separate
from the water and analyze separately. Shut oflF the
steam and drive air through the apparatus. At the same
time, heat the contents of the flask to 130° C. The
residue is analyzed for non-volatile oils. Acetone, if
present, will be- found in the aqueous as well as oily
layers of the distillate.
. Analysis of Non-volatile Portion Extracted from the
Ready Mixed Paint, as Previously Outlined. — As a rule,
very little information can be obtained, in the present
state of our knowledge of this subject, from the analysis
of a varnish or the non- volatile portions of a paint vehicle.
Most of the constants or characteristics of the various
ingredients which go to make up the varnish are so altered
in the process of cooking that it is often extremely difficult,
if not impossible, to distinguish them in the final material.
Rosin can generally be determined qualitatively and
quite often, quantitatively, but even here it is some-
times impossible to detect it in admixture with other
varnish resins.
Determination of Rosin
(Tu^tcheU Method) ^
Fatty or aliphatic acids are converted into ethyl
esters when acted upon by hydrochloric acid gas in their
' Amer. Soc. Testinjr Mat. Report t)f Comm. on Preservative
Coatings for Structural Materials, 190^^-1913.
- J. Soc. Chem. Ind. 1891, 10, 804.
ANALYSIS OF PAINT MATERIALS 327
alcoholic solution; rosin acids undergo little or no change,
abietic acid separating from the solution.
Weigh oflf 2 .to 3 g. of the mixed fatty or rosin acids
in a flask, dissolve in 10 volumes of absolute alcohol and
pass a current of dry, hydrochloric acid gas through the
solution, the flask being kept cool by immersion in cold
water. After about 45 minutes the reaction is complete,
when unabsorbed HCl gas escapes.
The flask is allowed to stand for one hour to permit
complete esterification and separation of the ethyl esters
and rosin acids. Dilute the contents of the flask with
five times its volume of water and boil until the aqueous
solution has become clear.
Gravimetric Method. — Mix the contents of the flask
with a little petroleum ether (b.p. below 80°) and trans-
fer to a separatory funnel. The flask is washed out with
the same solvent. The petroleum ether layer should be
about 50 c.c. in volume.
After shaking, the acid solution is removed, the
petroleum ether layer washed once with water, then
treated in the same funnel with 45 c.c. N/5 KOH and 5
c.c. of alcohol. The liquids in the funnel then separate
into: 1° a petroleum ether solution floating on top, and
2° an aqueous solution containing rosin soap. The
soap solution is run off, the rosin esters liberated by
decomposition with dilute hydrochloric acid, dissolved in
ether, and separated by evaporating the solvent on the
steam bath.
Volumetric Method. — The acidified mixture is poured
into a separatory funnel and the flask washed a few
times with ether. The mixture is thoroughly agitated,
then allowed to separate, the acid layer run out, and the
remaining ethereal solution containing the mixed ethyl
esters and rosin acids washed with water until free from
328 CHEMISTRY AND TECHNOLOGY OF PAINTS
hydrochloric acid. 50 c.c of alcohol is then added and the
solution titrated with standard alkali, using phenolphthalein
as indicator. The rosin acids react immediately, forming
rosin soaps; the ethyl esters remain unaffected.
The number of c.c. of N alkali is multiplied by 0.346,
giving the amoimt of rosin acids in the sample.
The gravimetric method is the more accurate one, due
to the difference in combining weights of the rosin acids
in different samples of rosin. The results obtained by
the Twitchell method are only approximately accurate.
In the case of a mixture of rosin acids, fatty and un-
sap>onifiable, saponify with alcoholic KOH and drive
off the alcohol (after dilution with water) by continued
boiling. Disregarding the undissolved unsaponifiable,
the aqueous soap solution is transferred to a separatory
funnel and shaken out with petroleum ether; this removes
the unsaponifiable. On treating with mineral acids, the
soap solution yields a mixture of rosin and fatty acids
which are separated by the Twitchell process.
In the volumetric method, the unsaponifiable need
not be separated as above. 2 g. of the mixed acids
and unsaponifiable are weighed off accurately, titrated
with N alkali and the number of c.c. (a) noted. Another
2 g. are treated with HCl gas and titrated with N alkali,
using (b) c.c; taking 346 as the combining weight for
rosin and 275 for the fatty acids (palmitic, stearic and
oleic), the weight of the rosin acids is b X 0.346; the weight
of fatty acids is (a — b) X 0.275, and the weight of the un-
saponifiable equals 100 — {b X0.346 + (a — b) X 0.275} .
Separation of Rosin Acids from Fatty. — After the
esterification process, we get a mixture of free acid and
esters, and after titration (e.g. in the volumetric process)
we get a mixture of rosin soap and ethyl esters of fatty
acids. If the alcohol is distilled off and the remaining
ANALYSIS OF PAINT MATERIALS 329
mixture treated with water, the soap is dissolved, leaving
the esters floating on top of the soap solution. The
two layers are separated and the soap solution, after
washing with ether to remove traces of esters, yields
rosin acids on acidulating. The ethyl esters are saponi-
fied by caustic alkali and the fatty acids separated.
Determination of Rosin
(Woljf dr Scholze Method) '
Quick Titrimetric Determination. — 2 to 5 g. of the
rosin — fatty — acid mixture, according to the quantity
weighed off, are dissolved in 10 to 20 c.c. of absolute
methyl or ethyl alcohol, treated with 5 to 10 c.c. of a
solution of one part of sulphuric acid in four parts
alcohol (methyl or ethyl) and boiled for two minutes
wth reflux condenser.
The reaction liquid is then treated with 5 to 10 volumes
of 7 to 10 per cent sodium chloride solution and the fatty
acid esters together with the rosin acids extracted with ether
or a mixture of ether and a little petroleum ether. The
aqueous solution is drawn off and agitated once or twice
with ether. The ethereal solutions are united, washed
twice with dilute sodium chloride solution (or when the
washed water is not neutral, to neutrality), and after
the addition of alcohol, titrated with N/2 KOH.
Assuming an average of 1 60 as the acid value of the
rosin acids and a correction for unsaponifiable fatty acids
of 1.5, and further taking "m'' as the amount of the
weighed fatty — acid — rosin mixture and "a" as the
number of c.c. of KOH used for neutralization, we obtain
as the rosin acid content in per cent, the following:
a. 17. 76
— ^ ^-5
m
1 Chem. Ztg. 7,^ (igu), 369, 382.
330 CHEMISTRY AND TECHNOLOGY OF PAINTS
The amount of rosin is approximately obtained. by
multiplying this value by 1.07.
Gravimetric. — 2 to 5 g. of the fatty acid mixture
are treated as in the first method. After neutraliza-
tion, I to 2 c.c. more of alcoholic KOH are added
and the ethereal solution repeatedly washed with water.
The wash water and soap solution are concentrated to a
small volume, transferred to a separatory funnel, acidi-
fied, and after the addition of the same amoimt of sodium
chloride solution, extracted two to three times. The
ethereal solution is dried with fused sodium sulphate and
the ether distilled off in a small flask.
The residue on cooling is dissolved in 10 c.c. of
absolute ethyl alcohol, and 5 c.c. of a mixture of i part
sulphuric acid with 0.4 parts alcohol are added. The
mixture is allowed to stand for i^ to 2 hours at
room temperature. It is then treated with 7 to 10 volumes
of 10 per cent sodium chloride solution, extracted with
ether two to three times, and the united ether extracts
(after twice washing with dilute sodium chloride and
drying with fused sodium sulphate) distilled off.
The percentage of the thus isolated rosin acids may be
multiplied by 1.07 in order to yield approximately the
rosin content.
Rosin and Rosin Oils
LicbermanU'Storch Reaction, — Dissolve the washed and
dried mixed acids (obtained by saponification of the
material to be analyzed and liberating the acids with
dilute hydrochloric or sulphuric acid) in acetic anhydride
on the water bath, cool and add a few drops of sulphuric
acid (specific gravity 1.53).
This acid is made by mixing 34.7 c.c. of concentrated
sulphuric acid with 35.7 c.c. of water, yielding 62.53
ANALYSIS OF PAINT MATERIALS 331
per cent sulphuric acid. The presence of rosin or rosin
oil is detected by a very fine reddish violet coloration
produced on the addition of the acid.
Detection. — Rosin oil may be detected by the Lie-
bermann-Storch reaction already mentioned, or by the
following : ^
Stannic bromide is prepared by adding bromine drop-
wise to granulated tin in a dry flask immersed in cold
water until an excess is present. Then a little more
bromine is added and the whole diluted with three to
four volumes of carbon disulphide. The reagent thus
obtained is stable.
To carry out the test, a few drops of the rosin oil are
placed in a dry test tube and dissolved in i . c.c. of car-
bon disulphide. Add the stannic bromide reagent grad-
ually. If rosin oil is present, the liquid assumes an
intense, brilliant, violet coloration.
It may be necessary to dilute with more carbon disul-
phide in order to bring out this color.
On standing, a violet sediment is formed in the tube
from which, after removing the liquid and warming the
residue with carbon disulphide, the purple coloration
is again obtained free from impurities.
In the presence of much mineral oil, mix the sample
with the solution of stannic bromide in carbon disulphide,
and then add, drop by drop, a solution of bromine and
carbon disulphide. This yields the coloration unmasked
by any due to the mineral oil.
. Rosin Oil
Rosin Spirit. — This is the lighter and more volatile
portion obtained in the dry distillation of rosin. It is
separated from the aqueous acetic acid layer, purified with
^ Allen, "Commercial Organic Analysis.^'
332 CHEMISTRY AND TECHNOLOGY OF PAINTS
sulphuric acid and caustic soda, and then re-distilled.
It is insoluble in water or alcohol, but soluble, in all pro-
portions, in ether, petroleum-ether and turpentine. The
specific gravity varies from 0.856 to 0.883.
Composition. — The hydro-carbons,^ of which this is
principally composed, include pentane and pentene and
their homologues, toluene and its homologues, tetra and
hexahydrotoluene and their homologues, terpenes, etc.
The characteristic constituent of rosin spirit is hep-
tine, C7H12, (methyl-propyl-allene). The compound boils
at 103° to 104° C, and has a specific gravity of 0.8031
at 20° C. It is soluble in alcohol and ether, absorbs
oxygen very readily, but does not affect ammoniacal
cuprous chloride or silver nitrate.
Rosin Oil. — This is the heavier and less volatile por-
tion obtained after the rosin spirit has been collected.
It generally has a strong fluorescence although the lat-
ter can be more or less destroyed by hydrogen i>eroxid,
the addition of nitro-benzol, nitro- or dinitrotoluene,
dinitronaphthalene, or by heating with sulphur. The
specific gravity of the crude rosin oil varies from 0.96
to I.I while the refined generally has a specific gravity
of 0.97 to 0.99.
Determination of Water
Qualitative. — Water in an oil, paint, dryer or varnish
may be detected by adding a few c.c. of dry mineral oil
to an equal quantity of the sample in a test tube and
shaking vigorously with a few grains of a strong dye like
er\'throsine, rhodamine or methylene blue. Coloration
proves the presence of water. Solvents like alcohol,
acetone or amyl acetate which dissolve these dyes must
of course be absent.
* Rcnard, Amer. Chcm. Phys. 1884 (6) i, 323.
ANALYSIS OF PAINT MATERIALS 333
The presence of an appreciable quantity of water in
an oil is indicated by the crackling produced when some
of it is heated in a test tube beyond 212° F.
Quantitative. — (i) In the case of non-volatile oils, about
5 g. are accurately weighed into a small evaporating dish
or watch-glass and dried in the air oven at 100-110° C.
for two hours. The loss in weight (except where volatile
fatty acids are present) is reported as moisture.
For accurate determinations, however, the above
method is open to serious objection. In the case of soya
bean oil, for example, owing to its comparatively high
content of volatile acids and glycerides, the results
obtained may be somewhat high; whereas in the case of
linseed oil the loss due to moisture may be more than
counter-balanced by the gain in weight due to oxidation.
With drying oils, the following method^ is therefore
recommended :
(2) A small Erlenmeyer flask fitted with a cork
through which pass two tubes, a long tube reaching down
to the bottom of the flask and a short one ending just
below the cork, is carefully dried and weighed. 5 g. of
oil are then introduced, the flask placed upon a steam
bath, and dry carbon dioxid, hydrogen or coal-gas
passed through the oil for i or 2 hours by connecting the
short tube to an air pump or aspirator. The flask is then
carefully dried and weighed.
(3) For the determination of water in oils like pine
oil, which always contain an appreciable quantity of
water, as well as in ready mixed paints, the method ^
outlined on the next page is very useful:
^ Determination of moisture in oils in a current of air — Son-
nenschein-Zeit. anal. Chem. 25, 373. J. Soc. Chem. Ind. 1886,
508.
- Michel, Chem. Ztg., 1913, 353.
334 CHEMISTRY AND TECHNOLOGY OF PAINTS
The substance containing water is distilled in an inert, water-
insoluble medium, lighter than water and having a higher boiling
point. For this purpose a mixture of toluene and xylene (1:2) is
found most suitable. On condensing the water sef)aratQ3 quanti-
tatively from the toluene-xylene mixture.
150 c.c. of a dry mixture of i pure toluene (b. p. 110° to 112® C.)
and I commercial, pure xylene are placed in a 300 c.c. Jena flask, and
the substance to be examined added. It is well to add a small spiral
of aluminium to produce uniform ebullition. The distillate is col-
lected in a separatory funnel about 10 cm. in diameter, and provided
with a glass cock having a bore of at least 5 mm. A 10 c.c. tube,
graduated in o.i or 0.05 c.c, in which the water is collected is at-
tached. The distillate, which is milky in appearance on account of
suspended water, is best separated by centrifuging. The amount of
water is then read off on the graduated tube. The toluene-xylene
may be dried over calcium chloride and used again.
(4) Determination of water by means of calcium
carbide (see U. S. Circular No. 97, of the Bureau of
Chemistry) .
Analysis of Oils
Specific Gravity, — This is determined at 15.5° C.
(60° F.). For most technical purposes the hydrometer
is universally used. Where, however, a greater degree of
accuracy is desired or where the amount of oil available
is rather small, the Westphal or Mohr's balance, the
si)ecific gravity bottle, SprengeFs picnometer or finallv
the analvtical balance mav be used. In the latter case
the si)ecific gravity is determined by means of a plummet
suspended from one of the balance beams and immersed
in the oil maintained at 15.5^0. The latter is contained
in a beaker or short cylinder placed upon a bridge so as
not to interfere with the balance pans.
If the i)lummct weighs in air a grams, in water w grams, and in
the oil at 15.5° C. grams.
ANALYSIS OF PAINT MATERIALS 335
a — w= loss in weight of plummet when immersed in water
= weight of vol. of water equal to vol. of plummet
a— o = wt. of vol. of oil equal to vol. of plummet
a —
= sp. gr. of oil
a — w
For the determination of the specific gravity of
viscous oils Lewkowitsch mentions the use of BruKl's
picnometer.
Eichhorn's araeopicnometer is used in the case of
very small quantities of oil.
In the latter case also the specific gravity of the oil
may be obtained by preparing a mixture of alcohol and
water so that a drop of the oil remains in suspension
wherever it is placed in the mixture. The sp. gr. of the
alcohol-water mixture is then determined by means of a
hydrometer.
It is advisable to determine the specific gravity at
^S'S^ C. Where, however, this is not feasible a correc-
tion^ must be made. This has been found by Allen to
be approximately the same for most vegetable and hydro-
carbon oils, and is equal to 0.00064 for 1° C. or 0.00035
for 1° F.
Saponification Value. — This expresses the number of
mgms. of potassium hydroxid necessary to completely
saponify the glycerides and fatty acids in i g. of oil.
Weigh„off in a 200 c.c. Erlenmeyer flask about 2 g. of
oil, add 25 c.c. (from a pipette) of N/2 alcoholic potash,
and heat on the steam bath for ^ to i hour with reflux
condenser. The contents of the flask should boil gently,
and should be agitated occasionally. When saponification
is complete, cool, add 5 drops of i per cent phenolphthalein
solution, and titrate the excess of alkali with N/2 hydro-
chloric acid solution. A blank titration is made with
^ Allen, Comm. Org. Anal. 1910, Vol. 2, pp. 49-51.
336 CHEMISTRY AND TECHNOLOGY OF PAINTS
25 c.c. N/2 alcoholic potash which has been heated as
outlined above.' The difference between the two titra-
tions shows the number of c.c. of N/2 HCl equivalent
to the KOH required to saponify the oil.
The alcoholic potash must be prepared from pure grain
alcohol (95 per cent) and chemically pure caustic potash.
Dissolve 40 g. of the stick potash in about 25 c.c. of
water and dilute with alcohol to i liter. After standing
for one day the solution may be filtered from the precipi-
tated potassium carbonate (which the stick potash always
contains) and set aside in a uniformly cool place.
The saponification value of an oil is valuable as a cri-
terion of its freedom from adulteration with mineral oils.
It does not, however, assist in detecting adulteration with
other vegetable oils, since most of the naturally occurring
vegetable oils have saponification values which vary be-
tween rather narrow limits. (See table, page 343.)
Acid Value. — This expresses the number of mgms. of
potassium hydroxid necessary to neutralize the free
fatty acids in i g. of oil.
Weigh oflf s to 15 g. of oil in an Erlenmeyer flask,
add 50 c.c. of alcohol, amyl alcohol, or ether-alcohol
mixture (1:1), add 2 to 3 drops of phenolphthalein and
titrate against N/io or N/5 caustic potash or soda. Of
the above solvents amyl alcohol and ether-alcohol dis-
solve most oils and resins almost completely. They
are especially valuable in the case of viscous oils. Where
alcohol alone is used it is generally best to heat it with the
oil for a short time on the steam bath before titrating in
order to completely extract the free fatty acids. Titrate
cold.
In the case of resins, and especially fossil resins, the
method must be modified somewhat. Dissolve about i g.
of the sample in 50 c.c. of a mixture of absolute alcohol
ANALYSIS OF PAINT MATERIALS 337
and benzol (i:i) or a similar mixture of alcohol and ether
by boiling, with reflux condenser, on the steam bath.
Titrate against N/2 or N/5 alcoholic alkali. It has been
found in this laboratory that aqueous alkali yields acid
values much higher than those obtained with alcoholic
alkali.
Oils which have been thickened by blowing generally
have a lower acid value. On the other hand we have
found that boiled bodied oils show a fair content of free
fatty acids.
Same OH Boiled
Varnish Oil
and Bodied
Sp.gr. 0.933
973
Acid. Val. 3 . i
14.8
Sapon. Val. 194.2
194.2
Iodine Val. 193 . 2
93-5
Iodine Value. — This figure represents the percentage
of iodine chloride (expressed in terms of iodine) absorbed
by the unsaturated glycerides and acids in i g. of oil.
Hiibl Method. — About 0.15 g. of drying oil, 0.25 g. of
semi-drying oil or i g. of non-drying oil is weighed off in
a capsule, placed in a 500 to 1,000 c.c. glass-stoppered
bottle, and dissolved in 10 c.c. of chloroform or carbon
tetrachloride. 25 c.c. of mercury iodochloride prepared
as shown below are added from a pipette. Empty the
pipette each time in exactly the same way, draining until
one or two drops have fallen. Moisten the glass stop-
per with potassium iodide solution, and set the bottle
aside in the dark. If after two hours the color of the
solution in the bottle is not a deep brownish red,
add another 25 c.c. of mercury solution. When the
reaction is complete the solution should contain an excess
of iodine at least equal to the amount absorbed. For
semi-drying oils allow 8 hours for complete absorption
338 CHEMISTRY AND TECHNOLOGY OF PAINTS
of the -iodine; for drying oils allow i8 hours. 15 c.c.
of 10 per cent potassium iodide solution (or more in case
a red ppt. of mercuric iodide is formed) are added,
and the contents of the flask diluted to about 500 c.c, at
the same time washing in any volatilized iodine trapped
by the potassium iodide solution on the stopper. The
excess iodine in the aqueous and chloroformic layers is
titrated against N/io sodium thiosulphate with frequent
agitation until the color of both layers is but faintly
yellow. A few c.c. of freshly prepared starch solution
are then added, and the titration continued imtil the
blue color is discharged. A blank containing exactly
the same quantities of solvent and mercury iodochloride
solution must be set aside along with the oil, and then
titrated after the addition of the same quantity of potas-
sium iodide and water.
The difference between the number of c.c. of sodium
thiosulphate required to neutralize the free iodine in the
blank and the excess iodine with the oil represents the
amount of iodine absorbed by the oil; from the latter
the iodine value can be calculated.
To prepare the mercury iodochloride solution (i)
25 g. of pure resublimed iodine are dissolved in 500 c.c.
of pure alcohol; (2) 30 g. of mercuric chloride are dis-
solved in the same quantity of alcohol in another bottle.
On mixing the above two solutions and allowing to stand
for 12 to 24 hours a solution of mercury iodochloride is
formed containing i molecule of iodine (I2) to one mole-
cule of HgClj. The mixed solution cannot be used for
making iodine value determinations when it is older than
24 hours. However, the two solutions in themselves
will keep indefinitely. It is therefore best to prepare
only as much iodochloride solution as is required.
The sodium thiosulphate solution is made by dis-
ANALYSIS OF PAINT MATERIALS 359
solving 25 g. of the crystals in i,ocx> c.c. of water. It
may be standardized by either of the following methods:
(a) Against Potassium Permanganate
Dissolve I or 2 g. of pure potassium iodide in a 400
c.c. flask, using a small amount of water; add 5 c.c. of
hydrochloric acid (1:1) and then 20 or 25 c.c. of an
accurately standardized N/io potassium permanganate
solution; the liberated iodine is titrated with the sodium
thiosulphate solution after diluting to 200 c.c. The
reaction involved is indicated below:
2KMn04-f loKI-f i6HCl= i2KCl-f 2MnCl2-f SHaO-f lol.
(b) Agaijist Potassium Dichr ornate
KaCraOi + 6KH-14HCI = 8KC1 -f 2CrCl3 -f 7H2O -f 61
Weigh off accurately 3.8633 g. of pure potassium
dichromate and dissolve in exactly 1,000 c.c. of water.
This quantity of dichromate solution is equivalent to
exactly 10 g. of iodine liberated according to the above
equation. In a 600 c.c. Erlenmeyer flask place 10 c.c.
of 10 per cent potassium iodide solution and 5 c.c. of
hydrochloric acid (1:1), and add exactly 20 c.c. of the
dichromate solution from a burette. Dilute to 300-400
c.c. and titrate against sodium thiosulphate after adding
starch solution. The end point is indicated by a change
in the color of the solution from deep blue to pale green.
The starch solution is best prepared, as needed, by
shaking up about 0.5 g. starch with 50 c.c. of water,
heating, and boiling for i or 2 minutes. The solution
should be cooled before being used. The dichromate
solution keeps indefinitely and may be used for stand-
ardizing the thiosulphate solution, the strength of- which
varies slightly with age.
340 CHEMISTRY AND TECHNOLOGY OF PAINTS
Wijs Method. — Dissolve 13 g. of iodine in glacial
acetic acid, and determine accurately the amount of
iodine present, using 25 c.c. for the determination. Then
pass dry chlorine gas into the solution until the color
changes suddenly from deep reddish brown to pale yellow,
due to the complete transformation of the iodine . into
iodine chloride. The iodine equivalent of this solution
must be exactly twice that of the original iodine solution.
If a titration shows more than double the iodine equiva-
lent, there is an excess of chlorine and enough iodine
should be added to combine with it. If the analysis
shows less than double the amount of iodine there is still
an excess of iodine and more chlorine should be added.
The iodine value determination is carried out exactly
as in the case of the Hiibl method; the time of absorp-
tion, however, is very much less, being ^ hour for non-
drying oils, I hoiu" for semi-drying oils, and 2 to 6 hours
for drying oils and marine animal oils.
According to Allen, absorption in the case of oils of
low iodine value is complete in 4 minutes, while those
of higher value require not more than 10 minutes, provided
too much oil is not taken. In this laboratory we have
made it a practice to allow about i hour for semi-drying
and drying oils.
The values obtained by the Wijs method are as
accurate as those obtained by the Hiibl method, and agree
very closely with the latter.
Bromide Test
It has been founds that on treating the ethereal
solutions of certain oils with a slight excess of bromine,
an insoluble precipitate is obtained.
^ Hehner & Mitchell, Analyst, 1898, 23, 313.
ANALYSIS OF PAINT MATERIALS 341
Method. — Dissolve i or 2 g. of oil in 40 c.c. of
ether, add a few c.c. of glacial acetic acid (the precipi-
tate formed with bromine is more granular when the acid
is used), stopper the flask, and cool to 5° C. Add
bromine, drop by drop, from a very fine pipette until the
brown coloration persists. The temperature must not
be allowed to rise.
Allow to stand for 3 hours at 5° C, filter (preferably
by suction); and wash four times with- ice-cold ether.
The residue is dried in the water oven and weighed.
The insoluble bromides obtained from linseed oil melt
at 140 to 145° C. and contain about 56 per cent bromine.
Those obtained from marine animal oils decompose be-
fore melting. This property, therefore, furnishes a good
method of detecting small amounts of the latter in
linseed oil.
The bromide test is useful in the examination of
boiled and bodied oils. Lewkowitsch ' has found that
the process of boiling linseed oil decreases the yield of
insoluble bromides.
On the other hand, an oil which has been bodied bv
blowing at a low temperature will give as high a yield
of bromides as the oil from which it is prepared.
Lewkowitsch recommends that the mixed fatty acids,
carefully prepared in an atmosphere of carbon dioxid
or hydrogen, be used in making the bromide test. The
precipitate then obtained is much easier to filter than
when the oil is used.
According to Eibner and Muggen thaler, ^ the bromide
test is carried out as follows:
2 g. of the mixed fatty acids are dissolved in 20 c.c.
of dry ether, and cooled to minus 10° C; 0.5 c.c.
^ Farben Ztg., 191 2, 33 ff.
^ Muggenthaler, Inaug. Dissert., 191 2, Augsburg.
342 CHEMISTRY AND TECHNOLOGY OF PAINTS
of bromine are added, drop by drop, from a very fine
pipette, allowing about 20 minutes for the addition of
this amoimt of bromine. Another 0.5 c.c. of bromine
are then added in 10 minutes' time. The temperature
must not go beyond — 5® C. The flask is corked and set
aside for 2 hours at — 10® C. The solution is then filtered
through a weighed asbestos filter, and washed 5 times
with dry ice cold ether, using 5 c.c. each time.
The precipitate is then dried for 2 hours at 80 to 85®
and cooled in a dessicator.
Hexabromides by the above Method
Fatty Adds from Per Cent
PerillaOil 64.12
Linseed Oil (Baltic) 57-96
Linseed Oil (Dutch) 51 . 73
Linseed Oil (La Plata) 51 .66
Linseed Oil (Indian) 50. 50
Tung Oil nil
Soya Bean Oil up to .78
Poppy Seed Oil nil
The melting point of the bromides obtained by Eibner
and Muggenthaler from the mixed fatty acids of linseed
oil was 177° C.
The following table will give an idea of the yield of
bromides obtained from various oils:
Material Per Cent *
PeriUaOil 53.6
Linseed (iodine value 181.) 23 . 14 : 23 . 52
Linseed Oil (iodine value 186.4) 24. 17
Linseed Oil (iodine value 190.4) 37-72
Tung Oil nU
Hempseed Oil 8.82
Walnut Oil i .42 : i . 9
Soya Bean Oil 3 . 73
Poppy Seed Oil nil
^ Lewkowitsch, Vol. I, p. 477.
ANALYSIS OF FAINT MATERIALS 343
Material Fer Cent
Soya Bean Oil 3 . 62
Com Oil nil
Cottonseed Oil "
Menhaden Oil 61.8
Cod Oil 32.68 : 30.62
Seal Oil 27 . 54 : 27 . 92
Whale Oil 15.54 125 .
Some Characteristics and Variables of Commercial Boiled Oils
Description
Somewhat thin and fluid.
Very viscid
Tacky, yielding strings. .
Ver>' thin.
Thin
Thin
Stout
Stout
Very stout.
Solid
\'ar>nng in consistence in the
same order, from thin to very
viscous
Double boiled oil, I
Commercial boiled oils, 8 samples.
Specific
gravity
at is-s"" C
0.947
0.948
0.961
0.972
0.982
0.983
0.9493
0.9595
0.9621
0.9355-
0.9474
Acid
value
13-4
24.9
32.6
8.8s
7.06
12.43
19.69
20.89
24.97
14.02
4.8
,2
,8
5
,1
7
.8
5
7
9
9
II,
18.
0.98
3 00
2.8-6.4
Saponifi-
cation
value
188.1-192
• • • • •
182.2
180.9
1795
189.3
185.6
183.0
193 9
188.7
189. 1
189. 1
186.6
187
187
192
191
192
192.8
187.5
192.2
2
2
3
o
3
Iodine
value
Per cent
101.3
77-3
73-7
145.1-157
149
7-153
159
100
95
83
79
76
71
16
o
7
6
6
I
2
I
1 .0
2
4
180. 4-183. 3
Characteristics op Boiled Oils (Lewkowitsch)
Name
Specific gravity
Iodine value
Ether-insoluble
bromides from
glycerides
Linseed oil (raw)
0.9308
0.9429
0.9449
0.9310
0.9388
0.9483
186.4
171.
169.96
180. 1
171. 2
169.7
Per cent
24.17
20.97
13.03
36.26-36.34
25 -73
30.19
Pale boiled linseed oil
Double " " "
Ozonised " "
(( << it
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# • • • •
344
CHEMISTRY AND TECHNOLOGY OF PAINTS
The Conversion of French (Metric) into English Measure
1 cubic centimeter -
17 mmmis.
2 cubic centimeters -
34
3
SI
4 " -
68
or I dram
8 minims.
5 " -
8S
(( T «
25 "
6 " -
lOI
« . U
41 "
7 " -
118
<i - f(
58 "
8 " -
ns
" 2 drams
IS "
9 " -
152
<c 2 "
32 "
ID " -
169
« J u
49 "
20 " -
338
u ^ u
38 "
30 "
507
" I ounce
dram 27 minims.
40 "
676
« - it
3 drams 16
50 "
84s
tt - tt
6 " S
60 " -
1014
" 2 ounces
" 54
70 "
1 183
« 2 ««
3 " 43
80 " -
1352
« 2 "
6 " 32
90 " -
1521
" 3 "
I " 21
100 " -
1690
" 3 "
4 " 10
1000 " »
I liter -
34
fluid ounces nearly, or 2^ pints.
The Conversion of French (Metric) into English Weight
The following table, which contains no error greater than one-tenth of a
grain, will suffice for most practical purposes:
I gram
■•
iSj grau
2 grams
—
30I "
3
»
46i "
4
«
6ii "
5
a
77i "
6
«
92! "
7
s
108
8
»
123? "
9
»
154* "
10
»
II
a
i69t "
185* "
12
a
13
a
200i "
14
=.
216
15
=
231} "
16
a
247 **
17
a
202^ "
18
a
277^ "
19
1^^
293i "
20
»
308? "
30
»
4^>3 "
40
a
6i7^T "
50
=
//If
(K>
a
026
70
B
loSol "
80
«.
1234! "
90
-
1389 "
100
-0
1543^ "
1000
-
1 kilogram
32 "Z-, I
or I dram li grain.
17JI grains.
325
I
I
I
2 drams
2
2
2
3
3
3
3
4
4
4
4
^
:>
7
10
12
15
18
20
23
25
dr., 125 gr.
48
3?
i8t
34!
49J
5i
205
36
7
S3i
8?.
43
I7i
si;
26
o\
345
9
43I
14
u
u
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tt
tt
tt
tt
tt
tt
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tt
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tt
tt
tt
tt
tt
tt
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it
tt
ANALYSIS OF PAINT MATERIALS
345
Metric System of Weights and Measures
Measures of Length
Denominations and Values
Equivalents in Use
Mvriameter
10,000 meters.
1 ,000 meters.
100 meters.
10 meters.
I meter,
i-ioth of a meter,
i-iooth of a meter,
i-ioooth of a meter.
6.2117 miles.
K.ilometer
328
393
39
3
62137 mile, or 3.280 ft. 10 ins.
Hectometer
Dekameter
Meter
Decimeter
Centimeter
Millimeter
feet and i inch.
7 inches.
37 inches.
937 inches.
3937 inch.
0394 inch.
Measures of Surface
Denominations and Values
Elquivalents in Use
Hectare
Are
Centare
10,000 square meters.
100 square meters.
I square meter.
2.471 acres.
119.6 square yards.
1,550. square mches.
Measures of Volume
Denominations and Values
Equivalents in Use
Names
No. of
Liters
Cubic Measures
Dry Measure
Wine Measure
Kiloliter or stere.
Hectoliter
Dekaliter
Liter
1,000
100
10
I
I-IO
l-IOO
I-IOOO
I cubic meter,
z-ioth cubic meter.
10 cubic decimeters.
I cubic decimeter,
i-ioth cubic decimeter.
10 cubic centimeters.
I cubic centimeter.
1 . 308 cubic yards.
2 bu. and 3.35 pecks.
9.08 quarts.
. 908 quart.
6. 1023 cubic inches.
.6102 cubic inch.
.061 cubic inch.
264.17 gallons.
26.417 gallons.
2.6417 gallons.
1.0^67 Quarts.
Deciliter
Centiliter
Milliliter
.845 Rill.
.338 fluid oz.
.27 fl. drm.
Weights
Denominations and Values
Equivalents
in Use
Names
Number of
Grams
Weight of Volume of Water
at its Maximum Density
Avoirdupob
Weight
Millier or Tonneau
1,000,000
100.000
10,000
1,000
100
10
I
l-IO
I-IOO
I-IOOO
I cubic meter.
I hectoliter.
10 liters.
I liter.
I deciliter.
10 cubic centimeters.
I cubic centimeter.
z-ioth of a cubic centimeter.
10 cubic millimeters.
I cubic millimeter.
2204.6 pounds.
220.46 iwunds.
22.046 pounds.
2 . 2046 pounds.
3.5274 ounces.
.3527 ounce.
15 432 grains.
I ■ 5432 grains.
.1543 grain.
.0154 grain.
Quintal
Mviiasram
Kilosrram or Kilo
Hectosram
Dekaeram
Gram
Decieram
Centiirram
Milligram
For measuring surfaces, the square dekameter is used under the term of ARE: the hectare, or 100
ares, is equal to about 2^ acres. The unit of canity is the cubic decimeter or LITER, and the series
of measures is formed in the same way as in the case of the table of lengths. The cubic meter is the
unit of measure for solid bodies, and b termed STERE. The unit of weight is the GR.XM, which is
the weight of one cubic centimeter of pure water weighed in a vacuum at the temperature of 4 deg.
Cent, or 39.2 deg. Fahr.. which is about its temperature of maximum density. In practice, the term
cubic centimeter, abbreviated c.c, is generally used instead of milliliter, and cubic meter instead of
kiloliter.
546
CHEMISTRY AND TECHNOLOGY OP PAINTS
Specific Gravity of Various Materials
Acetic Add
Acetone
Acetylene
Acrylic Add
Agate
Alabaster
Aluminium Oxid
" Sulphate
" i8H,0.
Alum, Potassium
" Soda
" Ammon. Chrome. .
" Potass. Chrome. . .
Amber
Ammonia (gas)
(liq.)
Ammonium Carbonate
NHiHCQ,..
Chloride .
" Nitrate
" Sulphate
" add
Amyl Acetate
" Alcohol
" Valerianate
Aniline
Anthracene
Anthracite
Antimony Oxid, Tri
" Tetra . .
" " Penta..
" Pentasulphide.
Arsenic Disulphidc
" Pentoxid
•* Trioxid
Asbestos
Asphalt
<<
1.0607 V
.788-.790
.92
1.063 1 y
2.5-2.8
2.3-2.8
3-75-3.99
2.71
1.62
I.7S
1.65
1.81278 (o.'O
I.O-I.I
•5971
.6234 (o. )
1.586
1.520 (i7.p
1.725 (15. )
1.7687 V
1.787
.8792 (20. J
.8144-8430
.8812 (o.^)
1.0276 (12.**)
1.147
M-1.7
5.2-5.7
4.07
3.78 ^
4.120 (o. )
3-4-3.6
3.99-4.25
3.646
1.2
I.I-I.5
(t
tt
it
ti
Barium Carbonate 4.27-4.37
Chloride 2H2O. .3.097 V
I*croxid 4958
Sulphide 4.25
Sulphate 4.33-4.476
Barley 51-69
Baryles 4-476
Basalt 2.7-3.2
Bees Wax (see wax).
Beef suet m.p. 3i.°-3i.5°
C 968
Bellmetal 8.81
Benzene b. p. 80.5"^ C 8799(2o.°C.)
Benzoic Acid 1.201 (21.°)
Blanr Fi.xc 4.02-4.53
Blue Vitriol 2.27
Bones 1.7-2.0
Borie Acid 1.46
Butter 865-868
Butyric Acid 9599 ^
«
({
«
«
«
«
«
«
admium Sulphide (artif.). . . 3.9-4.8 C
" " (Greenockitc).4.&-4.9
Caldum Carbide 2.22
Carbonate 2.72-2.95
Chloride (6 HtO) 1.654
" 2.26
Fluoride 3.15-3.18
Hydroxid 2.078
Oxid 3.i5-3«40
Sulphate 2.964
(Gypsum) 2.32
Sulphide 2.8
Tungstate 6.062
Camphor 992
Caoutchouc 92-.96
Carbolic Add 1.0597 (33.**)
Carbon (Amorphous). . . .z. 75-2. 10
" (Graphite) 2.10-2.585
" (Diamond) 3.47-3.5585
" Dioxid 1.529
** Disulphide 1.28
'' Monoxid 0.967
" Tetrachloride 1.59
Cast Iron 7.25
Cellulose 1.27-1.45
Charcoal (Airfilled) 0.4
" (Airfree) 1.4-1.5
Chlorine 2.491
Chloiofonn 1.5264
Chrome Alum Crt(S04)s.
KtS04. 24H,0 1.81278
Chromic Oxid 5.04
Chromium 6.92
Chromium Trioxid 2.67-2.82
Citric Add 1.542
Clay 3.85
Cobalt Chloride 2.94
Cobaltic Oxid (CoA) • • .4.81-5.6
Cocoabutter (m.p. 33.5°-
34.° Q 89-.91
Copal 1.04-1.14
Copper 8.91-8.96
Copper Carbonate, Basic. 3. 7-4.0
Cork 24
Corundum 4.0
Cotton (Airdr>') 1.4 7-1. 5
Cr>'olite AlFs3NaF 2.9
Cupric Hydroxid Z-S^
Oxid (Black) 6.32-^.43
Sulphate 3.516
Sulphate (5HsO).. 2.284
Sulphide 3.8-4.16
Cuprous Oxid (Red) 5.75-<>.oq
C>'mene b. p. 175.°-! 76.® 0.862 (20.**)
Dextrin 1*0384
Diamond 3.49-3.52
Dolomite 2.9
II
u
u
tt
ANALYSIS OF PAINT MATEIRALS
347
Specific Gkavity of Various Materials — Continued
Earth:
Gravel, dry 1.4
Humus 1.3-1.8
Lean 1.34
Loam 1.6-1.9
Ethane 1.036
Ether (Diethyl) 0.7183 (17.°)
Ethyl Acetate 8920-.9028
Ethyl Alcohol 7937 y
Ethylene 9784
Eucal>'ptol 9267 (20.°)
Eugenol 0630 (i8.°)
t<
«
((
n
Ferric Chloride 2.804- (10.8 )
Hydroxid 3.4"~3.9
Oxid 5.12-5.24
Ferrous Carbonate 3.70-3.87
Sulphate 1.86-1.90
Sulphide 4.75-5.04
Flax (airdry) - 1.5
Fish Oil 0.920-0.928
Formaldehyde (-20.°) 8153
Formic Acui 1.219-25°
1.244—0
Fumaric Acid 1.625
Furfural i.i594 -V
Gasoline (b. p. 70^.-90.°) . .66-.69
Gas Carbon i . 88
Glass:
Window 2.4-2.6
Mirror 2.45-2.72
Crystal 2.95
Flint 3-0-5-9
Glue 1.27
Gneiss 2.4-2.7
Granite 2.51-3.05
Graphite (Natural) 2.17-2.32
" (Artificial) 2.10-2.25
Gum Arabic 1.31-1.45
Guttapercha 981
Gypsum 2.32
Hemp (Air-dry) 1.5
Hornblende 3.0
Hydriodic Acid 4.3737A
Hydrobromic Acid 1.278A
Hydrochloric Acid 1.195 (8°)
Hydrocyanic Acid .697 (i8.°)
Hydrofluoric Acid 9879 (15.°)
Hydrogen 06949
Hydrogen-peroxid 1.4584 (0.°)
Hydrogen-sulphide 9-1. 1895
Hydroquinone 1.326
India Rubber 93
Indigo 1.35
Iodic Acid 4.629 (0.°)
Iodine 4.948 (17.°)
Iodoform' 4.09
Iron (pure) 7.85-7.88
" (gray pig) 7.03-7.13
" (white pig) 7.58-7.73
" (cast) 7.217
" (wrought) 7.86
" Bisulphide 4.86-5.18
" Sesquioxid 5.12
Ivory 1.82-1.92
Japan ^Wax (m. p. 53.5°-
54.5°) 992
Kaolin 2.2
Lactic Acid 1.2485
Lard (m. p. 41.5-42.C.). . .92-.94
Lava 2.00-3.00
Lead (milled sheet) 11.42
" (wire) 11.28
Acetate. 3H2O 2.50
Carbonate 6.43
** , Basic. . .6.323-6.492
" Chloride 5.8
Chromate 6.123 (15.*^)
Hydroxid
(3PbOH20) 7.592
** Iodide 6.12
" Nitrate 4.5
" Oxid (PbO) 9.2^.5
" (PbaOO 9.096(15.°)°
Sulphate 6.23
Sulphocyanate 3.82
Tungstate 8 235
Leather 86-1.02
Lime (unslacked) 1.3-1.4
" (slacked) 2.3-3.2
Limestone 1.86-2.84
Linolemn 1.15-1.3
Linseed Oil (raw) 93 -.934
" " (boiled) 934-.940
Litharge (natural) 7.83-7.98
" (artificial) 9.3-9.4
Lithimn Carbonate 2.1 1 1
Chloride 1.998-2.074
II
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It
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Malachite. 3.85
Manganese Chloride
(MnCl^HjO) 1.913
Manganese Nitrate 1,82
Oxid (M nO) . . 5 .09-5 . 1 8
" (Mn02)5.026
" (Mn2Q8)4.325-4.82
Sulphate
(MnS047H20). 2.092
Marble :
African 2.8
British 2.71
n
<<
a
n
348
CHEMISTRY AND TECHNOLOGY OF FAINTS
Specific Gra\ity of Various Materials — Continued
Marble:
Carrara 2.72
Egyptian, Green 2.67
Florentine 2.52
French 2.65
Marl 1.6-2.5
Masonry :
Ashlar Granite 2.37
Limestone 2.32-2.70
Millstone 2.01-2.51
Sandstone 2.61
Rubble (dr>') 2.21
" (mortar) 2.42
Meerschaum 99-1.28
Mercuric Chloride 5.32-5.46
" Oxid 11.0-11.29
Mercuric Sulphide:
(HgS black) 7-55-7. 70
(HgSred)..... 8.06-8.12
Mercurous Chloride:
(Calomel) 6.482-7.18
Methyl /Ucohol 7984 (15.°)
Methyl Ethyl Ether 7252 (0.°)
Mica 2.65-3.2
Milk (cow's) 1. 028-1. 035
Milk Sugar 1.525 (20. )
Molybdic Acid:
HjMoOiH^O 3.124 (15°)
Morphine 1.317-1.326
Mortar (hardened) 1.65
Mutton Suet (m.p.47.® C.) .92
Napthalene 1.1517
(15.° C.)
Na])hthol a 1.224 (4.° C.)
fi. 1. 217(4.° C.)
Xcatsfoot Oil 914 (39.°F.)
Nickel (rolled) 8.67
'^ (cast) 8.28
Nicotine i.oii
Nitranilinc m 1.43
P 1.4-24
V
Oats 43
Ochrc 3.50
Oleic Acid 8qoS
(12.° C.)
Oolitic Stones 1.89-2.6
Opal
Oxalic .\ci(l 1.^)53 (i8.°C.)
Oz)ne 1.058 (.\.)
Palmitic Acid 846^
(7.6" C.)
Palm Oil (m. p. 30.°C.). . . .905
PajHT 70- 1. 15
ParalVine:
m. p. 38.-52.°C 87-.88
m. p. 52.-50.
'C
.S8-.93
Pearls 2.72
Peat 1. 2-1. 5
Petroleum Ether:
b. p. 40.-7o."C 65-.66
Phenol 1.0597 isS'^'C.)
Phosphorus (yellow) 1.8232
(red) 2.11
Phthalic Acid i. 585-1. 593
** anhydride... 1.527 (4.'*^C.)
Picric Acid 1.813
Pinene 8587
(20.° C.)
Pitch 1.07-1.10
Plaster of Paris : 2.96
Platinum 21.52
Porcelain:
Berlin. •. 2.29
Meissen 2.49
Sevres 2.24
China 2.38
Portland Cement i. 25-1. 51
Potash 2.10
Potassium 875 ( 13°)
Bromide 2.756 -j*
Carbonate. ... 2.29
" (2H20)2.o43
Chlorate 2344 ( 1 7°)
Chloride i .994 y
Chromate. . . . 2.721 (4°)
Cyanide 1.52 (16°)
Bichromate. . .2.692 (4°)
P'crricyanide. .1.8109 07°)
Fcrn)cyanide . 1.8533 07^)
Hydro.xid 2.044
Iodide 3.043 1^24.3^)
Nitrate 2.1 (4.^)
Permanganate 2.70
Sulphate .?-6633 y
*' . Acid 2.245
Sulphide KjS. 2.13
Sulphocyanate i .006
Tartrate 1-975
Potatoes 1. 10
Pumice nat.) v~0O
(artif.j 2.2-2.5
Pyridin g855 (15.')
Pyrogallol i.4^>3 (40.';
Realgar AsjSa 3.4-3-6
Red Lead 9.07
Rosin 1.07
Ruby 3.95-4.02
Salt (table) 2. 15- 2.1 7
Sand (dry) 1.4- 1.05
'' (moist) 1.9-2.05
Sandstone 2.2-2.5
It
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A^'ALVSIS OF PAINT MATERIALS
349
Specific Gravity of Various Materials — Continued
<(
(<
n
it
Sapphire 3.95-4.02
Serpentine 2.4-2.7
Silicon (cryst.) 2.49 (io.°)
(graphitic) 2.0-2.5
(amorphous) 2.00
Silk (raw) 1.56
Silver Chloride 5-56i
Cyanide 3.95 ^
Nitrate 4.352 (19. )
Slate 2.65-2.7
Snow (loose) 1 25
Sodium Acetate 1.4
Bicarbonate 2.19-2.22
Bromide 2.95-3.08
Carbonate
(anhyd.) 2.43-2.51.
Carbonate
10 H2O 1.446 (17-)
Chloride 2.1741 (V)
Chromate 2.71 (16. )
Dichromate 2.52 (i6.°)
Hydroxid 2.13
Nitrate 2.267 V*
Nitrite 2.157*^
Oxid 2.805
Peroxid 2.805
Phosphate
Na2HP04i2H,0 1.5235 (16.**)
Potassium Tar-
trate 1.77
Sulphate (anhyd.) 2.67 1 V
10H2O.. 1.492 (20.**)
Sulphide NajS. . . 2.471
Sulphite 7H2O. . . 1 . 561
acid 1.48
Tartrate i-794
Tetraborate
(Borax) 1.694."®
Thiosulphate
5H2O 1.729 (17.°)
Tungstate 3.259 (17.5°)
Spathic Iron Ore 3-7-3-9
Stannous Chloride 2H2O. . 2.71 (15.5°)
Starch i. 53-1. 56
Stearic Acid 8428 ^
Stearin 9245 (65.®)
Steel 7.6-7.8
Strontium Chlorate 3.152
Strontium Nitrate 2.24-2.98
ti
It
n
ti
n
it
<<
it
a
a
a
a
a
it
a
<t
((
a
a
a
ti
a
a
a
ti
it
Sugar (cane) 1.588 (20.) ^
Sulphur nat 2.07
amorph. soft 1.9556 (0.°)
plastic S7 1.92
monoclinic S/3 . . .1.958
rhombic So 2.05-2.07 (0°)
Sulphur Dioxid 2.2639
Sulphuric Acid H2SO4. . . . 1.8342 V
Syenite 2.6-2.8
Talc 2.7
Tartaric Acid i. 666-1. 764
Terpincol 9357 (20.°)
Thymol (3:2:1) 0941 (0.°)
Titanium Oxid Ti02 3.75-4.-5
Toluene 866 y
Toluidine 998-1.046
Tungsten Oxid WO2:
(brown) 12. 11
Tungsten Oxid WO3:
(yellow) 7.16
Urea i .323
Uric Acid. i . 855-1 . 893
Verdigris 1.9
Wax, Bees:
Yellow m.p. 62.-62.5. "C .96-.965
White ni. p. 63.-63. 5®C. .96-.Q69
Wax, Japan:
(m. p. 53-S°-54-5°) • • -992
WTieat 7-.8
Wood (see table on page 351).
Wool (sheep) air-dry 1.32
Xvlene o 8032 (c.°)
m. 866 V
p 8801 (0.°)
ti
ti
Zinc Acetate i . 84
Blende ZnS 4.03-4.07
Carbonate 4.42-4.45
Chloride 2.91 V
(JXIQ 5.7^
Sulphate anhvd 3.6235 (15.°)
7H2O 1.964
Sulphide 3.98
it
ti
it
it
it
t(
a
(All temperatures, unless otherwise noted, are given in Centigrade degrees.)
350
CHEMISTRY AND TECHNOLOGY OF PAINTS
Si»EciFic Gravity of the Elements
Aluminium 2.66
Antimony 6.62
Argon 1.379 (Air-I)
Arsenic 5.73
Barium 3.75
Bismuth 9.80
Boron 2.50
Bromine 3.15 (Air-I)
Cadmium 8.64
Caesium 1.88
Calcium 8.64
Carbon.... I'H
3-53
Cerium 6.68
Chlorine ^.49 (Air-I)
Chromium 6.50
Cobalt 8.60
Columbium (Niobium). 7.20
Copper 8.933
Erbium 4.77
Fluorine 1.26 (Air-I)
Gadolinium 1.31
Gallium 5.95
Germanium 5*469
Glucinum (Beryllium).. 1.93
Gold 19.32
Helium 1 363 (Air-I)
Hydrogen o6g6 (Aii^I)
Indium 7.12
Iodine 4-943
Iridium 22.42
Iron 7-86
Krypton 2.818 (Air-I)
lanthanum 6.1545
Lead 11.37
Lithium 59
Magnesium 1.74
Manganese 7-39
Mcrcur>' 13-55
Molybdenum 8.60
Neodymium 6.956
Xeon 674 (.Vir-I)
Nickel 8.90
Nitrogen 96737
Osmium. 22^8
Oxygen.- 1.10535 (Air-I)
Palladium 11.40
Phosphorus:
(White) 1.83
(Red) 2.20
Platinum 21.50
Potassiimi 87
Praseodymium 6.4754
Radium
Rhodium 12.10
Rubidium 1.52
Ruthenium 12.26
Samarium 7.7-7.8
Scandium
Selenium 4.8
Silicon:
(Cryst.).' 2.39
(Graphitic) 2.00
(Amorph.) 2.35
Sflver 10.50
Sodium 978
Strontium 2.54
Sulphur 2.07
Tantalum 10.4
Tellurium 6.25
Terbium
Thallium 11.85
Thorium 1 i.oo
Thulium
Tin 7.29
Titanium 3.543
Tungsten:
(Wolframium) 19. i
Uranium 18.7
Vanadium 5.50
Xenon 4.422 (.\ir-I)
Ytterbium
Yttrium 3.80
Zinc 7.25
Zirconium 4.15
Pounds of Oil Required for Grinding 100 Pounds Various Dry Ph;ments
INTO Average Pastes*
Asbestine 32
Barytcs (Xat.) 9
Black, Ik>ne 50
Black. Drop 50
Black, Hydro Gas Carl>on 88
Black. Lamp 78
Blanc Fixe 25
Blue, Chinese or Prussian 62
Blue, Ultramarine 28
Brown, Mineral 24
BrowTi, Vandyke 58
China Clay 2S
Dutch Pink (Quercitron I^kc) 2S
(Jraphite (Plumbago), qo*'( 48
Clrecn, Pure, Light, Chrome 21
Green, Pure, Dark, Chrome 2S
ANALYSIS OF FAINT MATERIALS
351
Green, 25% Color, Light Chrome. 18
Green, 25% Color, Dark Chrome. 20
Green Earth (Terhi Verte) 32
Green, American, Paris 23
Green, English Paris 20
Green, Ultramarine '.'... 28
Gypsum 22
Lithopone 30-25
Ochre (American) 28
Ochre (French) 28
Ochre, Golden (Pure) ' 30
Red, Indian (Pure q8%) 20
Red, Tuscan 2q
Red, Venetian 23
Red Iron Oxid, Pure 28
Red Lead. . . ! 10
Sienna, Raw American 45
Sienna, Burnt Italian 45
Sienna, Raw Italian 52
Silex 24
Umber, Burnt American 36
Umber, Raw American 38
Umber, Burnt Turkey 47
Umber, Raw Turkey 48
Vermilion, American (Chrome Red) 18
Vermilion, English (Mercury) 14
White Lead (Basic Carbonate) 10
White Lead (Basic Sulphate) 11
White, Paris (Whiting) 20
Yellow, Lemon, Chrome 28
Yellow, Med., Chrome 30
Yellow, Orange, Chrome 20
Yellow, Dk. Orange, Chrome 18
Zinc Lead 12
Zinc Oxid (American), ordinary , . 18
Zinc Oxid (White Seal) 20
* These figures are approximately correct. For instance, lamp black is
given as 78 pounds. There are, however, some lampblacks which require as much
as 100 pounds, and others which require as low as 70 pounds, but 78 pounds is the
exact amount for commercially pure lampblack. This figure means that 100
pounds of lampblack will require 78 pounds (about 10 gallons) of oil to make
a stiff paste.
Specific Gravity of Various Woods
Acacia
Alder
Apple
Ash
Birch
Box
Cedar
Cherry
Ebony
Ebn
Fir
Mahogany. . .
Maple
Mountain Ash
Oak
Pear
Pine
Plum
Poplar
Willow
Air dry
58- -85
42- .68
C6- .84
57- -94
51- -77
91-1 . 16
57 .-.
76- .84
26 ...
56- .82
37- .75
56-1.06
53- .81
69- .89
69-1.03
61- .73
35- .60
68- .90
39- -59
49- -59
Fresh
75-1 00
63-1. 01
95-1 • 26
70-1.04
80-1 .09
20-1 . 26
05-1. 18
78-1 . 18
77-1-23
83-1.05
87-1 13
93-1 • 28
96-1 .07
40-1 . 07
87-1. 17
61-1 .07
79 •••
352
CHEMISTRY AND TECHNOLOGY OF PAINTS
Table Showing the Comparison of the Readings of Thermometers
Celsius, or Centigrade (C). R6aumur (R). Fahrenheit (F).
C
R
-30
— 24.0
- 25
- 20.0
- 20
— 16.0
- 15
- 12.0
- 10
- 8.0
- 5
- 40
- 4
- 32
- 3
- 2.4
- 2
- 1.6
— I
- 0.8
+
22.0
13.0
4.0
50
14.0
23.0
24.8
26.6
28.4
30.2
Freezing point of water.
o
I
2
3
4
5
6
7
8
9
10
II
12
13
14
15
16
17
iS
10
20
21
0.0
0.8
1.6
2.4
32
4.0
4.8
5-6
6.4
7.2
8.0
8.8
9.6
10.4
II . 2
12.0
12. ii
13.0
14 4
15 2
16.0
16,8
17. ^>
32.0
33-8
35-6
37-4
39 2
41.0
42.8
44.6
46.4
48.2
50.0
51.8
53 6
55 4
57 2
59 o
60.8
62.6
64.4
66 . 2
68 . o
6g.8
71.6
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
50
55
60
65
70
•• ^
80
85
95
100
R
18.4
19.2
20.0
20.8
21.6
22.4
23.2
24.0
24.8
25.6
26.4
27.2
28.0
28.8
29.6
304
31 2
32.0
32.8
33 6
34 4
35 2
36.0
40.0
44 o
48.0
52.0
56.0
(^K3.0
64.0
68.0
72.0
76 o
80.0
73 4
75 2
77 o
78.8
80.6
82.4
84 2
86.0
87.8
89.6
91.4
93 2
95 o
96.8
98.6
100.4
102.2
104.0
105.8
107.6
109
III
113
122
131
140
I4Q
i5'S
167
176
i«S5
194
203
212
4
2
o
o
o
o
o
o
o
o
o
o
o
o
Hoilinjj ix)int of water.
Readings on one scale can be changed into another by the following formuhe,
in whidi r indicates degrees of temperature:
Reau. to Tahr.
V R i s^^' = l^ I'
Reau. to Cent.
V R -. /' C
Cent, to Fahr.
^/" C + 32" = f I'
5
Cent, to Reau.
\r C = /" R
5
Fahr. to Cent.
Fahr. to Reau.
ANALYSIS OF PAINT MATERIALS
353
International Atomic Weights. 19 13
0-16
Aluminium Al 27-1
Antimony Sb 120-2
Argon A 39 • 88
Arsenic As 74*96
Barium Ba i37*37
Bismuth Bi 208-0
Boron B 11 -o
Bromine Br 79-92
Cadmium Cd 112-40
Careium Cs 132-81
Calcium Ca 40-07
Carbon C 12-00
Ceriimi Ce 140-25
Chlorine. CI 35*46
Chromium Cr 52-0
Cobalt Co 58^7
Columbium Cb 93-5
Copper Cu 63-57
Dysprosium Dy 162-5
Erbium Er 167-7
Europium Eu 152-0
Fluorine F 19-0
Gadolinium Gd 157-3
Gallium Ga 69-9
Germanium Ge 72-5
Glucinum Gl 9-1
Gold Au 197 • 2
Helium He 3-99
Holmiimi Ho 163 - 5
Hydrogen H i -ooS
Indium In 114-8
Iodine I 1 26 • 92
Iridium Ir 193 - 1
Iron Fe 55*84
Krypton Kr 8292
Lanthanum La 139-0
Lead Pb 207-10
Lithium Li 6-94
Lutecium Lu 1740
Magnesium Mg 24-32
Manganese Mn 54-93
Mercury Hg 200-6
o = 16
Molybdenum Mo 96-0
Neodymium Nd 144-3
Neon Ne 20-2
Nickel Ni 58-68
Niton(radium emanation). Nt 222-4
Nitrogen N 14-01
Osmium Os 190-9
Oxygen O 16.00
PaUadium. Pd 106 - 7
Phosphorus P 31 -04
Platinum Pt 195 - 2
Potassium K 39 * 10
Praseodymium Pr 140-6
Radium Ra 226-4
Rhodium Rh 102-9
Rubidium Rb 85-45
Ruthenium Ru loi - 7
Samarium Sa 150-4
Scandium Sc 44-1
Selenium Se 79-2
Silicon Si 28-3
Silver Ag 107-88
Sodium Na 23-00
Strontium. Sr 87-63
Sulphur S 32-07
Tantalum Ta 181 -5
Tellurium Te 127-5
Terbium Tb 159-2
Thallium Tl 204-0
Thorium. Th 232-4
Thulium Tm 168-5
Tin Sn 119-0
TiUnium Ti 48-1
Tungsten W 184-0
Uranium. U 238-5
Vanadium V 51-0
Xenon Xe 130 • 2
Ytterbium(Neoytterbium)Yb 172-0
Yttrium Yt 89-0
Zinc Zn 65-37
Zirconium Zr 90-6
PHOTOMICROGRAPHS
I.
2.
3.
4.
6.
7.
8.
9.
NUMBER PAGE
Corroded WTiite Lead. 29
Old Process A\Tiite Lead. 30
White Lead (New Process). 31
Sublimed White Lead. 36
Standard Zinc Lead White. 38
Ozark White. 40
American Zinc Oxid. 43
French Green Seal Oxid. 44
Lithopone (dry). 47
10. Lithopone (ground in oil). 48
11. Litharge. 54
12. Litharge. 55
13. French Orange Mineral. 57
14. Red Lead (Photomicrograph
of paint film freshly ap-
plied, showing separation of
the pigment from the oil). 58
15. Red Lead (Photomicrograph
of red lead applied one hour
after mixing, showing sepa-
ration and air bells en-
cysted in film). 59
English Venetian Red. 64
American Venetian Red. 65
American Hematite. 66
Indian Red. 66
American Burnt Sierma. 72
Prince's Metallic. 75
Ordinary American Washed
Ochre. 79
American Washed Ochre. 80
J. F. L. S. Ochre. 81
Ultramarine Blue. 85
26. Ultramarine Blue (ground in
oil). 8s
27. Artificial Cobalt Blue. 88
28. Lampblack. 99
16.
17.
18.
19.
20.
21.
22.
23-
24.
25.
NUMBER
29. Carbon Black.
30. Natural Graphite.
31. Natural Graphite.
32. Artificial Graphite.
33. Artificial Graphite.
34. Fine Charcoal.
35. Charcoal Black.
36. Vine Black.
37. Wood Pulp Black.
38. Drop Black.
39. Drop Black.
40. Barytes.
41. Bar>'tes, /\merican.
42. Blanc Fixe.
43. Blanc Fixe.
44. Barium Carbonate.
45. Silica or Silex.
46. Silica.
47. Silica.
48. Infusorial Earth.
49. Diatoms.
50. Diatoms.
51. Clay.
52. China Clay.
53. Colloidal Clay.
54. Asbestine.
55. WTiiting.
56. Gilder's A\Tiiting.
57. Calciimi Carbonate, artificial.
58. Talc (Soapstonc).
59. Basic Magnesium Carbonate.
60. Alumina Hydrate.
61. American Gypsum.
62. American Gypsum.
63. American Terra Alba.
64. Calcium Sulphate (Gypsum).
65. P>cnch Terra Alba.
PACE
100
lOI
102
103
104
105
los
106
107
108
108
113
115
117
120
122
123
123
124
126
127
127
128
129
129
130
131
131
132
132
133
^33
136
136
136
136
137
356
PHOTOMICROGRAPHS
NUMBER PAGE
66. Terra Alba (French Gypsum). 137
67. Calcium Sulphate. 137
68. Precipitated Calcium Sul-
phate. 137
69. Photomicrograph of Portland
cement floor composed of 2
parts sand and i [>art
cement. 147
70. Highly magnified view of a
NUMBER PAGE
fine crack in Portland
cement construction. 148
71. Olive green fungus growing
on paint. 284
72. Penicilium Crustaceum. 285
73. Aspergillus Niger. 2S5
74. Aspergillus Niger. 286
75. Aspergillus Flavus. 286
76. Cladosphorium Herbarum. 287
INDEX
Acetylene black, as black toner,- io8
Acid value, det. in oils and resins, 336
Adulteration of white lead, 16, 17
Alabaster, use in making g>'psum, 137
Alum salts, use in fireproofing wood,
129
Anti-fouling paints, preparation of, 144,
145
Antwerp blue — see Prussian blue
Asbestine, analysis of, 130, 312
composition, 128
fireproof paint, use in, 1 28
shingle stain, use in, 156
Asbestos, fireproof paints, use in, 128
identification, 130
Aspergillus Flavus, 286
Aspergillus Niger, 286
Asphalts, influence of sunlight on, 261,
262
chemical composition of, 262
Bancroft — see lithopone
Barium carbonate, 121
analysis of, 315
manufacture of, 122
paints, value in, 122
versus Witherite, 122
Barium sulph., artificial — see blanc fixe
natural — see barytes
Barytes, 112
analysis of, 312^ 314
bleaching of, 116
bulkuig of, in oil and paint, 115
chirt rockin, 116
exposure tests of paints containing,
114
filler, value as, 113
versus other fillers, 115
occurrence, 115
para red, use of with, 113
treatment of, 116
wearing qualities of paints contain-
ing, 112, 114
Battleship gray, blanc fixe, use of, in,
118
exposure tests of, on "Panther," iig
manufacture of, 119
Beck ton white — see lithopone
Benzine, 238
and condensation of water due to
evaporation of, 239
distillation of, 241
use in paints, 238
Benzol, composition, production and
cost of, 243
crude, 243
properties of, 244
use in black paints, 244
use in finishing coats (objection to),
244
use to prevent livering, 244
use in priming paints, 244
Benzol black, 107
behavior in oil, 108
Bitumens, chemical composition of, 262
exposure tests of, 264
paints, deterioration of, 264
sunlight, effect of, on, 261, 262
Black lead, — see graphite
Black pigments, 97
analysis of, 309
Prussian blue in detection of, 309
varieties of, 97
acetylene, 108
benzol, 107, 108
bone, 97
carbon, 100
color in varnish, 98
Black pigments, varieties of,
drop, 106, 107
358
INDEX
Black pigments, varieties of,
ivory, io6
lamp, 98, 99
mineral, 109
sugar house, 97
toner, 97
vine, 104
Blanc fixe, 116
analysis of, 310
consumption of, in U. S., 120
manufacture of, 116, 121
salt water, effect of, on paints con-
taining, 120
use in enamels, 117, 118
" " lakes, 117, 118
" " linoleum, 120
" " oil cloth, 120
" " paints, as reinforcing pigment,
118
" " paper, 116, 117
" " printing ink, 120
Bleaching, of oils, 171, 172
Blood stone — see iron oxids
Blown oils, analysis of, 1 79
Blue lead, composition and properties, 61
pigments, 84
Boiled linseed oil, specifications for, 1 74,
175
Bone black, 97
Branding, of white lead, 16, 17
Branding of mixed paint, 17
Breninig — see silex
Bromide test, 340
Bronze blue — see Prussian blue
Brooke — sec soya beans
Brown pigments, 71
Burnt ochre. 74
Burnt sienna, 71
American, 71, 72
Italian, 72, 73
Burnt umber, 63
Calcium carl^onatc — see whiting
resinate, formation of, in concrete
ll(H)rs, 147
as i^rotcction for concrete from
machiner>' oils, 147
sulphate — sec gypsum
Carbon black, properties, 100
dioxid, effect of, on white pigments,
140
paints, 141
wearing qualities of, 141
Cassel brown — sec Vandyke brown
Cement paints — see concrete paints
Cement, Portland, use of, in paints, 146,
149
Chalk — see whiting.
Charcoal, alkalinity in, 104
manufacture of, 104
paint pigment, use as, 104
preservative coating from, and
litharge, 104
saponification of, paints in presence
of moisture, 105
uses in oil cloth and coated leather,
Charlton white — see lithopone
China base oil, 185
Chinese blue — see Prussian blue
wood oil, 180
acidity of, effect in enamels, 185,
186
adulteration of, 184
detection of, 187
analysis of, 182
calcium oleate in, 182
Canton, 181
chemical composition of, 183
constants of, 182
drying of, 180, 181
gelatinization, 181, 185
Hankow, 181
heating of, 181, 184
odoroF, means of detection, 182, 185
paints, 181
enamel, 182
polN-merization of, 181, 185
raw, in flat wall paints, 186, 187
rosin varnish, 187
specifications for, 190
uses, 183, 184
in baking enamels, 187
in cement floor paints, 187
waterproof (qualities of, 183
wearing qualities of, 183
INDEX
359
Chirt rock — see barytes
Chlorophyll ia linseed oil, 169
Chrome green, analysis of, 304
composition of, 92
permanence of, 93
Chrome yellow, analysis of, 303
composition of, 82
permanence of, 82
preparation of, 81
Chromium oxid, 93
manufacture of, 94
use in delicate greens, 94
Cinnabar, 66
Clay, 127
analysis of, 128, 312
presence of, in ochres and siennas, 127
uses, in paints to prevent settling, 127
in cheap barrel and paste paints,
127
water in, 127
wearing qualities of paint containing,
127
Coal, use of, in paints, 106
Coarse paints, value as priming coats, 259
Cobalt blue, 87, 88
determination of, in paints, 88
distinction from lithopone, 88
permanence of, 88
strength of, 88
with driers, 89
Cobalt driers, 247
amount required to dry oil, 249
incorporating, in oils, 252
linoleate, 251
liquid, 252
oleate, 251
oleoresinate, 251
leslnate, 250
tungate, 251
use with soya bean oil, 200
Cobalt salts, 247
acetate, 252
oxid, 252
oxidation of, 248
Combining mediums, 254
rosin-mixing varnishes as, 254
rubber solutions as, 254
water as, 254
Conmionwealth white — see whiting
Complex ore, low grade, 37
Concrete floors, abrasion and dusting
of, 146
acids, use of, in painting of, 146
calcium resinate as protection for, 147
lime, free, in, 147
machinery oils, effect of, on, 147
resin acids for coating, 147
zinc sulphate, use in, 148
Concrete paints, 146
consumption of, 148
use of Chinese wood oil and copals in,
147, 148
"Cooler," 18
Copper, anti-fouling paints, 145
green, 96
Com oil, 214
analytical constants, 215^ 216
drying of, 235
■
treatment of, 215
uses, 214
versus soya bean oil, 215
Corrosion, electrolytic, of structural
steel, 276
electrolytic, at anode, 276, 277, 278
paint vehicles as protective • agents
against, 266
Creosote, use in shingle stain, 156
Damar enamels, 151
gum, acid value of, 151
varnish, preparation of, 152
Damp-resisting paints, 149, 150
adhesion of, to brick and mortar, 149,
ISO
use of Chinese wood oil and linseed
oil in, 150
Diatoms, nature of, and composition,
126
use in lakes and paints, 126
Dickens's "Bright Star in the East," 31
Drier, cobalt, 247
Japan, 163
Japanners' Prussian brown as, 163
lead sulphate as, 163
lime oil, 163
litharge as, 162
360
INDEX
Drier, manganese salts as, 162, 163
Prussian blue as, 163
red lead as, 162
zinc sulphate as, 163
"Drifts," 19
Drop black, 106, 107
Durcx white — see barium carbonate
Blast Indian red, 65
Eibner and Muggenthaler — see bro-
mide test
Emulsiiiers, 256, 257
Enamel oil, typical analysis of, 1 79
Enamel paints, composition, 151
damar type of, 151
definitions of, 150
lithopone, wood oil, rosin type
of, 152
stand oil t>'pe of, 152
Erythrophyll in linseed oil, 171
Exposure tests of paint vehicles, 266,
272, 273
Extenders — see fillers
Famau — see lithopone
Ferric oxid paints — see iron oxid
paints
Ferric oxids — see iron oxids
Fillers, as adulterants, iii, 112
bar>' tes as, 113
battleship gray, use in, in
clay, use of, as, 127
inert, value in paints, 1 10
occurrence in pigments, iii, 127
principal, value of, 112
wearing qualities of paints as affected
by. 141
Fine grinding. 259
for finishing coats, 250
and rubbing of varnishes, 260
Fire proof paints. 128. 129
alum s;ilts, usi' in, 129
for shingles. 130
Fish oil, analytical constants of men-
haden. 207
analytical constants of varieties of,
204
drying of, 208
herring oil, 210
pseudo versus genuine, 203
red lead, use of, in, 207
sp>ecifications for, 209
treatment of, 205
Fish oil, use of, in baking japans, 207
in enamel leather and printing
ink, 206
in exterior paints, 205
in [>aints, 204
on seacoast, 207
in smokestack paints, 207, 208
in waterproof paints, 207
Floor paints — see concrete paints
Foots, in linseed oil, 171
Fuller's earth, 126, 127
Fungi, definition of, 284
fungicides, use of, for, 286
growth of, on paints, 284
varieties of, 286
Gilder's white — see whiting
Glycerides, influence of sunlight on, 263
Gmelin — see ultramarine blue
Graphite, Acheson, 102
analysis of, 310
behavior of, in linseed oil with other
pigments, 101
brown, 102
exjwsure of, and iron oxid, 102
fillers in, use of, 103
film, adaptability for reixainting. 103
green, 102
paint film, 103
paints, 141
properties of, loi
red, 102
Green aniline lakes, 95
chrome, 92, 304
Grinding, fine, 259
paste, 18, 19
surfaces of mills, 19
Ciuinet — see ultramarine blue
(Jypsum, alabaster as source of, 137
analysis of, 139, 311
calcium chloride as source of. 138
comjKisition and occurrence of, 135
free lime in, 136
INDEX
Gypsum, hydration of, 137
presence of, in Venetian red, 138
use of, in freight car color, 138
as paint filler, 136
water in, 136
Harrison Red, 69
Helio Fast Red, 69, 70
Hematite — see iron oxids
Hermann — see ultramarine blue, 85
Herring oil, 210
acidity of, 211
drying of, 214
treatment of, 213, 214
Hough process — see pine oil, 229
Huhlmann — see ultramarine blue, 8$
Hygiene, painters', 281
Hypha — see fungi, 284
H>'pochlorite of lime, in shingle stain,
156
Indian red — see iron oxids, 64
Infusorial earth, 122
composition and properties, 1 25
use of, in paints, 126
Iodine value, det. of, of oils, 337
Iron — see corrosion
Iron oxids, analysis of, 299
bloodstone, 65
East Indian red, 65
hematite, 65
Indian red, 64
manufacture of, 63
paints, 141, 142, 144
Persian,' 63, 65
protective pigments, 62
rouge, watch case, 66
rubber pigments, 62
shingle stain, 156
Venetian reds, 63, 64
Ivory black, coach color, 106
extract of, 106
properties, 106
Japanners' Prussian brown, 163
Jersey lily white — see Iithoix)ne
Kaolin, 127, 128 — sec clay
361
Kaolinite, 128
Kauri dust, use of, in japan driers, 163
Kieselguhr, 126
Koettig — see ultramarine blue, 86
Lake base — see blanc fixe
Lampblack, 98, 99
Lapis lazuli, 84
"Lead," meaning of, 19
Lead, oxids, 53
peroxid, det. of, in red lead, 298
sulphate, basic, anal, of, 290, 26, 35,
38,39
drier, 163
Les Val6es — see soya beans, 194
Leverkus — see ultramarine blue, 86
Leverkusen — see ultramarine blue, 86
Leykauf, see ultramarine blue, 87
Leykauf and Zeltner — see ultramarine
blue, 86
Liebermann, Storch reaction, 330
Light — see sunlight
"Light wood " — see pine oil, 231
Lime oil, 163
Linseed oil, adulteration of, 159
analysis, typical of, 1 74
analytical constants of, 158, 161
Baltic, 158
bleaching of, 171
blown, typical analysis of, 1 79
^ boiled, specifications for, 1 74, 1 75
* "breathing of," 168, 169
Calcutta, 159
carbon dioxid from, 168, 169
coloring matter in, 169, 171
deterioration of, 173
driers and drying of, 162, 163
extraction of, 160
film, porosity of, 164, 166
new process, 160
N. American, 158
paints, 164, 165
patent leather, use of, in, 165
reactions of, with pigments in can,
173
refining of, 169
saponification of, 164
specifications for, 174, 175
362
INDEX
Linseed oil, treating of, 165
waterproof qualities of, 164, 165
Liquid paint, 23
Litharge, as drier, 162
-cement, 56
flake, 54
livering of, in mixed paints, 53
manufacture of, 53
testing of, 53
use, in black paints, 53
in preservative paints, 53
Lithol red, 70
Lithopone, 26, 46
analysis of, 296
barium sulphate in, 48
composition of, 46
darkening of, by sunlight, 49 '
enamels, 152
manufacture of, 46, 47
paint pigment, 49
yellow color of, cause, 49
zinc oxid in, 48, 51
Long oil, 177, 178
fillers in, 14, 16, 141
fire- resisting, 155
flat, wall, 154
floor, 15s
graphite, 141
guarantees of manufacturers, 143
iron oxid, 144
manufacture of, 18
origin of, 13
Portland cement, 146, 149
primer on wood, 143
shingle, 155
storage of, 20, 21, 22
tinting, tanks for, locating, 20
water in, 13, 17
wearing qualities of, effect of fillers
on, 141
white, exposure tests of, 140
white lead, effect of rain water and
carbon dioxid on, 140
zinc vs. white lead, 140, 142
Mixers, liquid, 18
for mixed paint, 20
Maize oil — see com oil
Manganese salts, as driers, 162, 163
Marble dust, as filler, 130, 133, 134
Marble oil, 176
Mercur>' sulphide, 66
analysis of, 302
^lildew. formation of, 284
Mills, for grinding paints, iq, 20
Milori blue — see Prussian blue
Mineral black, C()miK)sition and prop-
erties, log
Mixed paints, analysis of, 324
anti-f.)ulin^. 144, 145
ben/.ol. in. 244
bleadiin^ of white, 173
brandinK of. 17
carl>on, 141
coiKTete, 146
consumption of. 14. 14^
covering qualities of. 141
(lamp-resistinj;. 140, 150
distribution of. in factory. 20
enamel, 150, 151, 152, 153
ferric oxid, i2i, 142
Naphtha — see benzine
Nitroparatoluidine — see Hello Fast Red
O'Brien — see lithopone, 49
Ochre, American yellow, 78
burnt, 74
clay in, 127
cream, 79
French, brands of, 79, 80
golden, 79
gray, 79
grt^n, 80
white, 79
Oils, acid value, det. of, 336
analysis of, 334
blown, typical analysis of, 179
bromide test for, 340
Chinese wcxxl, 180
corn. 214
enamel. ty[)ical analysis of, 179
fish. 203
herring, 210
icMline value, det. of, 337
Ja[)anese wood, 180
INDEX
363
Oils, Japanners* Prussian brown, 178
linseed, 158
long, 177
maize, 215
marble, 176
menhaden, 203
pine, 228
short, 177
soya bean, 192
specific gravity, det. of, 334
stand, 176
Tung, 180
Turpentine, 217
Oleum white — see lithopone
Orange mineral — see red lead
Orr — see lithopone, 46
Orr's white — see lithopone
Ozark white, 26, 39
composition and manufactureof,4o,4i
Paint, bactericidal action of, 284
bitumen, exposure tests of, 264
coarse, as priming coats, 259
fillers, use in, 14
fine, as finishing coats, 259
floor, 19
fungi in, 284
mildew on, 284
mixed — see mixed paints
paste, manufacture of, 18, 19
pigments, analysis of, 317
sunlight, influence of, 261
varnish, 19
Painters' hygiene, 281, 282
" Panther," exposure test of Battleship
gray on, 119
Paranitraniline red, 67
barytes, use of, in, 113
bleeding of, 69
manufacture of, 68
reactions, 67
permanence of, 68
uses of, 69
Paris blue — see Prussian blue
white — see whiting
Paste grinding, 18, 19, 23
advantages of, 25
mills, 23, 24, 25
Patent leather, use of linseed oil in, 165
Penecilium crustaceum, 286
"Periphery," 19
Permanent white — see blanc fixe
Persian oxids, 63, 65
Pigments, analysis of, 317
reinforcing, no
Pine oil, analysis of, 237
distillation of, fractional, 237
extraction of, 228, 230
bath process, 231
destruct.-distill. process, 230
Hough process, 229
formation of, 233
light wood as source of, 231
long leaf, 232
relation to turpentine and rosin, 232
solvent properties of, 234
terpineol in, 233
use of, in paints, 234, 235
water in, detection of, 234, 235, 332
Ponolith — see lithopone
Potassium dichromate, use in shingle
stains, 156
Priming coat for wood, 143
Princess metallic, 71, 74
composition of, 76
mining and milling of, 75
paints, wearing qualities of, 144
properties and uses of, 75
Princess mineral brown, 74
Prussian blue, analysis of, 91, 306
composition and manufacture of,
properties of and uses, 90, 91
varieties of, 90
Prussian brown, japanners, as drier, 163
Prussian brown oil, japanners, 178
Putty, whiting, 132
Quartz, 123
Quicksilver vermilion, 66
Raw sienna, 78
Red lead, analysis of, 298
drier, use of, for oil, 162
Dutch boy. 56
field test vs. laborator>' test, 60
366 INI
Whiti; leaiJ; soap, formation of, 30
sublimed, 26, 35, 38, jg
analysis of, 2Qb
suli^uu gaset, effect of, on, 33
' tozidty of, 30, $1
vuieties of, »6
Venus zinc ond, 143
weathering of, 32, 33
White minersl primer-— see whiting .
VUte piEments, 26, 27, 28
venus other lilleis, 134
WUting, addity la paints, corrected by,
Uia1)w of, 31 1
t^-product, 134 . .
duratnUty of, in oil, 131
filler, 13a, 133, 134 '
Dunufaaute of, 130, 131
putty, 132
idiile miner&l primer, 134
Williams — see anti-footiag paints, 144
Witherite, 122
Wc4f and Scbobe.niethod, fitt iMin, 329
Wood oil, todn *"wb"'1», 15a
Wood turpentine, compo»tion, 113
manufacture of, 221
uses in paints, 123
YeQoiv, chrome, 81, 82, 3C(3.
odirc, 7a
oxid So
IHgmcnts, 78
Snc chrcHnatc, as
green, composition, prapeities, u
95
leac},i6-
aaalysia of, 191
oomplex ore, 37
- composition of , 38
minufactuie of, 37
white, standard, 37
MiDes^ Ppii)t> '6
oiid,4t
kna!yins irf, 193
brands, ,|4, 43 ,
Xantophyll, in linseed oi
Xylol, 246
169
consumption of, 41
oijdatjoa of, in oil, 41
vs. oth« driers, 41, 43
P^t,i3
eipoiure test of, 14a
vs. white lead paint, 141
sulphur gases, effect of, on,
zinc sulphate in, 44, 45
sulphate, as drier, 163
Zinojc, 45
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Craig, J. W., and Woodward, W. P. Questions and Answers About
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Craig, T. Motion of a Solid in a Fuel. (Science Series No. 49.) . i6mo,
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Cramp, W. Continuous Current Machine Design Sto,
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Crosskey, L. R., and Thaw, J. Advanced Perspective 8vo, i 50
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Dadourian, H. M. Analytical Mechanics i2mo, *3 00
Dana, R. T. Handbook of Construction plant i2mo, leather, *5 00
Danby, A. Natural Rock Asphalts and Bitiunens 8vo,
Davenport, C. The Book. (Westminster Series.) 8vo,
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Davies, F. H. Electric Power and Traction 8vo,
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Deerr, N. Sugar Cane 8vo,
Deite, C. Manual of Soapmaking. Trans, by S. T. King 4to,
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Diamond Drilling for Gold *5 00
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Derr, W. L. Block Signal Operation Oblong 1 2mo,
Maintenance-of-Way Engineering {In Prcjxiradon.)
Desaint, A. Three Hundred Shades and How to Mix Thera 8vo,
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Devey, R. G. Mill and Factory Wiring. (Installation Manuals Series.;
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Dichmann, Carl. Basic Open-Hearth Steel Process i2mo,
Dieterich, K. Analysis of Resins, Balsams, and Gum Resins. . . . 8vo,
Dinger, Lieut. H. C. Care and Operation of Naval Machinery i2mo,
Dixon, D. B. Machinist's and Steam Engineer's Practical Calculator.
i6mo, morocco, i 25
Doble, W. A. Power Plant Construction on the Pacific Coast {In /'/•«.<> ■
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Dodge, G. F. Diagrams for Designing Reinforced Concrete Structures,
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Dron, R. W. Mining Formulas i2mo,
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Dumesny, P., and Noyer, J. Wood Products, Distillates, and Extracts.
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A Handbook on Modem Explosives Svo,
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Eliot, C. W., and Storer, F. H. Compendious Manual of Qualitative
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Ellis, G. Modem Technical Drawing Svo,
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Applied Thermodjmamics Svo,
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Ermen, W. F. A. Materials Used in Sizing Svo,
Erwin, M. The Universe and the Atom i2mo,
Evans, C. A. Macadamized Roads {fn Press.)
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Ewing, A. J. Magnetic Induction in Iron ... 8vo, '
Fairie, J. Notes on Lead Ores umo, ■
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Fairweather, W. C. Foreign and Colonis] Patent Laws Svo, *
Faik, M. S. Cement Mortars and Concretes Bvo, *
Fanning, J. T. Hydraulic and Water-supply Engineering 8vo, "
Fay, I. W. The Coal-tar Colors 8to, •
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Fish, J. C. L. Lettering of Working Drawings .Oblong 8vo.
Mathematics of the Paper Location of a Railroad, .paper, iicno, *
Fisher, H. K. C, and Darby, W. C. Submarine Cable Testing 8vo, *
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Svo,
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Vol. U. The Utilization of Induced Currents. . *
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A Handbook for the Electrical Laboratory and Testing Room. Two
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Fleury, P. Preparation and Uses of While Zinc Paints Svo, *
Flynn, P. J. Flow of Water. (Science Series No. 84.) . . unio, 1
■ Hydraulic Tables, (Science Series No. 66.) . .... . . . .i6mo, 1
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Foster, H. A. Electrical Engineers' Pocket-book. (.sVwhM EdUion.)
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Foster, Gen. J. G. Submarine Blasting in Boston iMass.) Harbor 4(0,
Fowie, F. F. Overhead Transmission Line Crossings iimo, *
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Fox, W. G. Transition Curves. (Science Series No. 1 10.) t6mo, 1
Fox, W.. and Thomas, C. W. Practical Course in Mechanical Draw-
ing """Of
Foye, J. C. Chemical Problems. (Science Series No. 6g.j . . . i6mo, •
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Francis, J. B. Lowell Hydraulic Experiments , 4(0, 11
Franzen, H. Exercises in Gas Analysis . lamo, '
French, J, W. Machine Toots, a vols 4to, "i
Freudemacber, P. W. Electrical Mining Installations. < Installation
Manuals Series.) ..... . . . . timo, *
Frith, J. Alternating Current Design 8vo, ';
Fritsch, J. Manufacture of Chemical Manures. Trans, by D. Grant.
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Fumell, J. Paints, Colors, Oils, and Varnishes 8vo. *i oo
Gairdner, J. W. I. Earthwork 8vo (/n Press.)
Gant, L. W. Elements of Electric Traction 8vo, *a 50
Garcia, A. J. R. V. Spanish-English Railway Terms 8vo, *4 50
Garforth, W. E. Rules for Recovering Coal Mines after Explosions and
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Garrard, C. C. Electric Switch and Controlling Gear (/n Press.)
Gaudard, J. Foundations. (Science Series No. 34.) i6mo, 050
Gear, H. B., and Williams, P. F. Electric Central Station Distribution
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Geerligs, H. C. P. Cane Sugar and Its lianufacture 8vo, *5 00
Geikie, J. Structural and Field Geology 8vo, *4 00
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Gerber,N. Analysis of Milk, Condensed Milk, and Infants' Milk-Food. 8vo, i 25
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Gibson, A. H. Hydraulics and Its Application 8yo, '''s 00
Water Hammer in Hydraulic Pipe Lines i2mo, *2 00
Gibson, A. H., and Ritchie, E. G. Circular Arc Bow Girder 4to, *3 50
Gilbreth, F. B. Motion Study i2mo, *a 00
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Field System lamo, leather, *3 00
Primer of Scientific Management i2mo, *i 00
Gillette, H. P. Handbook of Cost Data i2mo, leather, '*'5 00
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and Dana, R. T. Cest Keeping and Management Engineering . Svo, *3 50
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12 D. VAX NOSTRAND CO.'S SHORT TITLE CATALOG
Goodeve, T. M. Textbook on the Steam-engine 12 mo,
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Gould, E. S. Arithmetic of the Steam-engine i2mo,
Calculus. (Science Series No. 112.) i6mo,
High Masom'y Dams. (Science Series No. 22.) i6mo,
Practical Hydrostatics and Hydrostatic Formulas. (Science Series
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Gratacap, L. P. A Popular Guide to Bftinerals 8vo,
Gray, J. Electrical Influence Machines i2mo,
Marine Boiler Design lamo,
Greenhill, G. Djmamics of Mechanical Flight 8vo,
Greenwood, £. Classified Guide to Technical and Commercial Books. 8vo,
Gregorius, R. Mineral Waxes. Trans, by C. Salter i2mo,
Griffiths, A. B. A Treatise on Manures i2mo,
Dental Metallurgy 8vo,
Gross, E. Hops 8vo,
Grossman, J. Ammonia and Its Compounds i2mo,
Groth, L. A. Welding and Cutting Metals by Gases or Electricity.
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Grover, F. Modem Gas and Oil Engines 8vo,
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Gunther, C. 0. Integration
Garden, R. L. Traverse Tables folio, half morocco,
Guy, A. £. Experiments on the Flexure of Beams 8vo,
Haenig, A. Emery and Emery Industry 8vo,
Hainbach, R. Pottery Decoration. Trans, by C. Salter iimo,
Hale, W. J. Calculations of General Chemistry i2mo,
Hall, C. H. Chemistry of Paints and Paint Vehicles iimo,
Hall, G. L. Elementary Theory of Alternate Current Working. .. .8vo,
Hall, R. H. Governors and Governing Mechanism i2mo,
Hall, W. S. Elements of the Differential and Integral Calculus 8vo,
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Haller, G. F., and Cunningham, E. T. The Tesla Coil i2mo,
Halsey, F. A. Slide Valve Gears i2mo,
The Use of the Slide Rule. (Science Series No. 114.) i6mo,
Worm and Spiral Gearing. (Science Series No. 116.) i6mo,
Hamilton, W. G. Useful Information for Railway Men i6mo,
Hammer, W. J. Radium and Other Radio-active Substances 8vo,
Hancock, H. Textbook of Mechanics and Hydrostatics 8vo,
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Hardy, E. Elementary Principles of Graphic Statics i2mo,
Haring, H. Engineering Law.
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Harris, S. M. Practical Topographical Surveying i In Press.)
Harrison, W. B. The Mechanics* Tool-book i2mo.
Hart, J. W. External Plumbing Work 8vo,
Hints to Plumbers on Joint Wiping 8vo,
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D. VAN XOSTRAND CO/S SHORT TITLE CATALOG 13
Principles of Hot Water Supply 8vo, *3 00
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HawkeswOTth, J. Graphical Handbook for Reinforced Concrete Design.
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Hay, A. Alternating Currents 8vo, *2 50
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Hayes, H. V. Public Utilities, Their Cost New and Depreciation. . .8vo, '"a 00
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Heaviside, O. Electromagnetic Theory. Vols. I and U Svo, each, *5 00
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Henrici, O. Skeleton Structures Svo, i 50
Bering, D. W. Essentials of Physics for College Students Svo, *i 75
Hering-Shaw, A. Domestic Sanitation and Plumbing. Two Vols.. .Svo, *$ 00
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Herrmann, G. The Graphical Statics of Mechanism. Trans, by A. P.
Smith i2mo, 2 00
Herzfeld, J. Testing of Yarns and Textile Fabrics Svo, *3 50
Hildebrandt, A. Airships, Past and Present Svo, "^3 50
Uildenbrand, B. W. Cable-Making. (Science Series No. 32.) i6mo, o 50
Hilditch, T. P. A Concise History of Chemistry iimo, *i 25
Hill, C. S. Concrete Inspection i6mo, *! 00
Hill, J. W. The Purification of Public Water Supplies. New Edition.
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Interpretation of Water Analysis (in Press.)
Hill, M. J. M. The Theory of Proportion Svo, *2 50
Hiroi, I. Plate Girder Construction. ( Science Series No. 95.) . . . i6mo, o 50
Statically-Indeterminate Stresses i2mo, *2 00
Hirshfdd, C. F. Engineering Thermodynamics. (Science Series No. 45.)
i6mo, o 50
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Hobart, H. M. Heavy Electrical Engineering 8vo, *4 53
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Hobart, H. M. Electric Propulsion of Ships ; . . .8vo, *2 00
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Hobbs, W. R. P. The Arithmetic of Electrical Measurements i2mo, o 50
Hoif, J. N. Paint and Varnish Facts and Formulas i2mo, *i 50
Hole, W. The Distribution of Gas 8vo, *7 50
HoUey, A. L. Railway Practice folio, 6 00
Holmes, A. B. The Electric Light Popularly Explained. ..iimo, paper, 50
Hopkins, N. M. Experimental Electrochemistry 8vo,
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Hopkinson, J., Shoolbred, J. N., and Day, R. E. Dynamic Electricity.
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Houghton, C. E. The Elements of Mechanics of Materials x2mo, *2 00
Houllevigue, L. The Evolution of the Sciences 8vo, *2 00
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Hovenden, F. Practical Mathematics for Young Engineers i2mo, *i 00
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Ho worth, J. Repairing and Riveting Glass, China and Earthenware.
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Hubbard, E The Utilization of Wood-waste Svo, *2 00
Hiibner, J. Bleaching and Dyeing of Vegetable and Fibrous Materials.
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Humphreys, A. C. The Business Features of Engineering Practice. Svo, *i 25
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Hurst, G. H. Handbook of the Theory of Color Svo, *2 50
— Dictionary of Chemicals and Raw Products Svo, *3 od
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Also published in three parts.
Part L Dynamics and Heat * J 25
Part II. Sound and Light ' i 25
Part III. Magnetism and Electricity ' i 50
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ilri Prfss.)
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Button, W. S. Steam-boiler Construction 8vo, 6 00
The Works* Manager's Handbook Svo, 6 00
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Ingham, A. £. Gearing. A practical treatise 8vo,
Ingle, H. Mannal of Agricultural Chemistry 870,
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The Fan i2mo,
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Jacob, A., and Gotdd, £. S. On the Designing and Construction of
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Jannettaz, E. Guide to the Determination of Rocks. Trans, by G. W.
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Jehl, F. Manufacture of Carbons. x 8vo,
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Jepson, G. Cams and the Principles of their Construction 8vo,
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Joddn, W. Arithmetic of the Gold and Silversmith iimo,
Johnson, J. H. Arc Lamps and Accessory Apparatus. (Installation
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Johnson, W. McA. The Metallurgy of Nickel (/« Pre paraliou .)
Johnston, J. F. W., and Cameron, C. Elements of Agricultural Chemistry
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Jones, H. C. Electrical Nature of Matter and Radioactivity i2mo,
Evolution of Solutions ( /« Press. )
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Joynson, F. H. Designing and Construction of Machine Gearing . . 8vo,
Jiiptner, H. F. V. Siderology : The Science of Iron 8vo,
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Keim, A. W. Prevention of Dampness in Buildings 8vo,
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l6 D. VAN NOSTRAND CO.'S SHORT TITLE CATALOG
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50
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I
50
50
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