oxide, the coloring matter.
The French ochers proper are somewhat richer in the
proportion of oxide of iron contained in them than that
of the sample cited above. Notwithstanding that they
average stronger in coloring matter than the Oxford
ochers, they are commonly of a lighter and brighter tone.
This is remarkable, because ochers which usually contain
large proportions of ferric oxide, are darker than those
which contain less. It is very hard to account satis-
factorily why it is that some samples are so much richer
in tone than others of nearly the same chemical compo-
sition. Some lack in brilliancy, or, if not in that, are found
lame elsewhere. It is therefore useless to look to a
chemical analysis for a reason to explain these things.
Some of the better grades of French ochers make
beautiful cream and buff tints with white lead or zinc
white so rich in fact as to suggest to one used only to
the American ochers that possibly they had been doc-
tored up with chrome yellow. This richness is inherent,
66 MODERN PIGMENTS
and the tints made from them will never fade, as would
those from a chromed ocher.
It is customary with many color grinders to tone up
ochers with chrome yellow. When this is done, and sold
under the proper name, and labeled as a "Chrome Ocher,"
it is all right. That is a legitimate transaction; but
when this is done to tone up a poor ocher so that it will
sell better, then it is all wrong, and is bound to work an
injury upon the unwary users of it.
If such ochers are used for solid painting, the chrome
yellow will fade away, leaving the ocher its original ugly
color. If such an ocher has been used in making tints,
the rich tone will disappear even more quickly.
The painter using these may possibly have saved a
quarter of a dollar in the difference of cost between a
good French ocher and what he used in the making up
of his tint if the house was a good-sized one, but in repu-
tation the loss cannot be computed in quarter dollars.
Had he used the right ocher, the gain would have been
permanent; the customer would have been better satis-
fied, even if he knew little about color. Every neighbor
seeing the house holding its color so well and so long
would have become a free "ad" for the painter. The
wishy-washy, fady, spotty-looking house is another
kind of an "ad" loudly proclaiming that the man who
did the job did not know his business.
Page after page of ocher analyses might be given, but
would only confuse the mind. All they do or would
prove is that there is no such thing as uniformity to be
found in them, and this has been said so often here that
it is unnecessary to prove it again by crowding in useless
testimony.
The reader has been advised to buy his ocher ground
in oil. There are good reasons for it. % Manufacturers
YELLOW PIGMENTS 67
of reputation are much more careful buyers than the
average painter can be. They know how and where to
buy pure French ochers. They have men in their employ
who are experts in this line. They can buy direct from
the importers, if it be so that they do not import it them-
selves, and will receive it in the original packages from
the custom house as imported. The painter who thinks
he can tell unerringly a French ocher when he sees it, or
who depends upon the stenciled marks on the barrels
bought from his supply houses or the jobbers, will in nine
cases out of ten be imposed upon. Besides, the best
reason of all is, that allowing he can buy just the same as
the manufacturer, he certainly cannot afford to grind it.
The grinding of a good ocher should never be done in
an iron mill, as, when it is so ground, it is likely to lose
brilliancy, or at least impair some richness. Stone mills
are the only ones fit for grinding ocher, or, for that matter,
all other colors, including the blacks, if brightness of the
color is of any object and it surely ought to be. The
above is said for the benefit of the painter who is thinking
about the buying of a paint mill so he can buy his colors
dry and pure (?), and save his hard-earned dollars instead
of giving them away for colors ready ground. The man
who owns a collection of paint mills, and has them
rusting away down in the back part of the cellar, knows
better, and the advice given does not concern him. All
the money that a painter has ever saved by the grinding
of his own colors can be put inside of a very small pocket
book, and in old-fashioned copper cent cart-wheels at
that.
Grinding colors so that they retain their brilliancy of
tone, and are ground to the last degree of fineness, is a
science and trade by itself. The painter can never learn
it thoroughly, nor can he equip himself rightly for it except
68 MODERN PIGMENTS
at too great an expense for it ever to pay him to do so.
There is quite a capital tied up in such an equipment,
which in an ordinary shop will be required to work for
possibly one week out of the fifty-two in the year. This
machinery will have to lie idle fifty-one weeks yearly.
There will be nothing for it to do. If he intends to keep
it going so as to sell to others, all right and good but
then the painter will find it more profitable to give up
the painting business, as he cannot expect to make a
success of both at the same time.
There are few shops, aside from those of large railway
systems, where the grinding of colors has ever been done
advantageously. In these there is a set of men whose
sole business it is to attend to the grinding, and who, if
they are not expert grinders at the beginning, soon become
skilled by keeping constantly at it. Even in these large
shops there is no economy claimed by the master mechan-
ics. The cost of installing and maintaining the grind-
ing plant, and the wages of the employees detailed to
that work, more than eat up the difference in cost between
the dry pigments and the ground goods prepared ready
for thinners, bought in large quantities, as these shops do.
The large capital invested in expensive machinery
which is constantly needing repairs soon disgusts the
most enthusiastic, and, like all dearly bought experience, it
comes to stay with them. Hence the discarded machinery
in the cellar, or that which goes to the scrap-iron heap.
This lengthy advice and warning is given here, not so
much because it appertains to ocher more than to any
of the other colors, but because ochers being the first ones
of the colored pigments under consideration, it seemed
best to give it under that head, and it will not have to be
repeated again. Such advice and warning is needed,
and if followed it will save dollars to the man heeding it.
YELLOW PIGMENTS 69
During a lifetime, the author has visited in one capacity
or another for nearly fifty years several thousand paint
shops. In a very few he has seen mills set up; in many
more he has seen the self-same mills relegated to some out-
of-the-way place. In all instances where the owners were
asked about the saving effected by their use, the reply has
been nothing.
Upon returning after a year's absence to shops where
they had been set up, they had disappeared, and the same
answer was received as the reason for their removal.
As nearly all the characteristics presented so far apper-
tain mainly to the class of ocher known as the " silicate "
or the French and English, more will be said now of the
special characteristics which belong to the other or
argillaceous class those where the clay base predom-
inates.
Reasons have been given why the silicate ochers were
the best for outside painting, and why they should be
used for that purpose to the exclusion of the clay ochers.
But for distemper or water-color work the French and
English ochers are not nearly as well adapted as the
American clay ochers.
Most people are better acquainted with them under the
name of American ocher than any other. In the markets,
the division of ochers into the silicate or clay classes is
unknown. The French and English or the American
in various grades is all the classification they receive.
To all intents and purposes it really amounts to the same,
as the imported represents the silicate class, and the
American the clay class, because about all found so far
in America partake more or less of this character.
In distemper painting, clay ochers work better. They
cover better, and, what is still more prized, they look better
than the silicate class does; so that what they lack for oil
70 MODERN PIGMENTS
painting becomes their chief redeeming quality in water-
color work.
This class of ocher is very common. It is found in
nearly all if not in every state in the Union. Like the
other ochers, it varies very much in composition. So far,
the best that have been found are mined in Eastern Vir-
ginia on the Appomattox River below Petersburg, and
in the same section at Bermuda Hundreds.
Those Eastern Virginia ochers contain a fair per-
centage of silica in their base, but the alumina predomi-
nates. They carry about 25 per cent of ferric oxide.
Their tone is fair, and they may be said to be the nearest
approach to the imported many jobbers sell them as
" Rochelle." These represent the better grade of American
ochers found so far.
On the other extreme in Missouri down on the
Iron Mountain railroad below St. Louis there are found
numerous beds of ocher. The remarkable peculiarity of
these ochers is the enormous quantity of ferric oxide
they carry. Some samples analyze as much as 85 per cent
ranging down to 20 per cent. A fair average for that
section will be more than double that of the imported
class. But what the oxide of iron makes up in quantity
it seems to lose in quality, the tone being universally
poor.
Their chief use so far has been found in the burning
of them into a red ocher and in compounding them with
talc in the making of a cheap Venetian red or rather
mortar color for which they are excellent, being so strong.
Enormous quantities are sold for that purpose alone.
Some of these very strong American ochers are also
compounded with ground talc, gypsum or silicate earths;
some being sold as French and English, but the bulk
going under the American name.
YELLOW PIGMENTS 71
Most of the American ochers are semi-transparent, and
but for their tones could be classed with perfect propriety
with the siennas. Some which do come nearest to them
are so classed and sold as American siennas. This trans-
parency is not apparent in distemper painting, but it
becomes decidedly objectionable for oil painting, even
when compounded with silicate earths, and thus rendered
unobjectionable in all other respects.
In addition to the natural ochers, tons upon tons of that
pigment are made artificially. When a good quality
of ferric oxide is used as the coloring agent, and a right
base selected to hold it up just right, the product can
hardly help being a good one. There surely cannot be
any good reasons given why an excellent artificial ocher
should not be made as well as an artificial Venetian red,
which these all are. What is said under the heading of
that pigment regarding preparation will give the reader
an idea of how these artificial earths are produced and
prepared for use. There is this difference, however, that
in the case of ochers no calcination is necessary all that
is needed is mixing and triturating. The base is usually
either china, clay, talc and silicate earth in such propor-
tions as best suit the compounders.
The great trouble heretofore has been in the finding of
an hydrate-ferric oxide of sufficient richness to compete
with the French and English imported ochers. So far,
all these artificial ochers have had a lame side in that they
are all too transparent in oil to be palmed off as genuine
French ocher upon the expert ones at least.
For all that, the French and English ochers are silicious;
they are very opaque, much more so than any sample of
American containing twice the quantity of coloring matter.
It looks as if the atomic formation of the hydrate-ferric
oxide from over the water was somehow different from
72 MODERN PIGMENTS
that produced on this side of the big pond or is this due
to the forms of atoms in some of the bases? There seems
to be an opening here for scientists to investigate.
This kind of transparent ferric oxide appears to be
found in Italy, as many of the Italian siennas contain
twice as much as many of the French ochers, and yet they
are very transparent for all that.
As soon as the proper hydrate-ferric oxide can be
found or artificially produced with as good tone as that
in the imported ochers and as opaque, so that they can
be duplicated at will here, there will be as little French
and English ochers imported as there is now of English
Venetian red. In all likelihood it is only a question of
time when this will take place. All signs point that
way now, and the painter will gladly hail the day when
he can depend to a nicety upon the uniformity and exact
composition of his ochers.
Some of these artificial ochers that have been very
carefully compounded, can be relied upon as being very
superior for outside painting to those that are mined
and that are of uncertain composition. Samples which
were examined and tested show up nearly as good as
many that are imported.
As ocher is the most important of all the colored earth
pigments to the painter, no apology is needed for having
given so much space to its consideration.
CHAPTER VI
CHROME YELLOW
YELLOW PIGMENTS (Continued)
General Remarks Concerning Them.
THE chrome yellows follow the ochers in the list of
yellow pigments, and rank next to them in usefulness and
importance to the painter.
These yellows are all chemically made in color works,
and are found of various tones covering the whole range,
from a deep orange bordering upon a true red to the
lightest of the canary yellows.
Commercially they are known as "canary yellow,"
which is the palest; "lemon yellow" comes next to
that in paleness ; " medium chrome yellow " is the neu-
tral chromate of lead, and its shade borders neither
towards the orange nor the lemon. It is neutral in this
respect as well as chemically. "Orange chrome yellow"
runs in a variety of shades from a very pale tinge of
that color to a deep almost scarlet shade of it.
Some manufacturers make it up in three shades,
which they mark as "pale orange," 'orange," and
"deep orange."
The medium chrome yellow is the only one of the whole
range that is the true "chromate of lead." The varia-
tions from it are due to the addition of other substances
added purposely to produce them. So the medium or
neutral chromate of lead, is the base, or standard, from
73
74 MODERN PIGMENTS
which all the others are mere variations. For this reason
its character will be the first one considered.
MEDIUM CHROME YELLOW
Its Characteristics, Chemistry, and Manufacture
Chrome yellow has been known under various names
for over a century. As its name indicates, it is derived
from chromic acid and a lead base.
It is easily obtained as a precipitate by simply making
solutions of the acetate or of the nitrate of lead, which
are soluble in water, and of bichromate of potash, and
pouring the two solutions together in a settling tank.
The chrome yellow will instantly precipitate.
Color manufacturers, however, make it from white lead,
as it is more economical to produce in that way. This
being insoluble in water, requires more manipulations
and boiling. The proportions used are about four pounds
of white lead to one of the bichromate of potash.
CANARY AND LEMON CHROME YELLOW
Manufacture
The lighter shades of chrome yellow are made in
precisely the same manner as the ,neutral chromate
of lead or medium chrome yellow, with this difference:
lead sulphate or sulphuric acid must be added to
the white lead and bichromate of potash. According,
therefore, to the quantity of the sulphate of lead added,
will be the canary, lemon, or intermediate light shades.
The more sulphate of lead that goes in the mixing liquids,
the lighter will be the shade; the less of it used, the nearer
will it approach to that of the medium chrome yellow.
Sulphate of lead is a legitimate component part of a
pale chrome yellow, however much of an adulterant it
YELLOW PIGMENTS 75
may be when added to an already made and precipitated
medium chrome yellow or an orange shade where it has
no business to be, and where, if found, it is a sure indication
of adulteration.
The sulphate of lead must be added before the precipi-
tation of the solutions so as to produce the lighter shades,
as it combines with them then, which it will not do if
added afterward.
Sulphate of lead is frequently used as an adulterant
of medium chrome yellow by simply mixing the two by
trituration. In such a mixture the color of the medium
yellow is not changed.
Chemists who are not familiar with this fact, and who
have not made the study of paint-making a specialty,
frequently make queer mistakes in their analysis. They
know that chrome yellow is neutral chromate of lead, so
that when the lighter samples of chrome yellow are handed
to them for analysis they are sure to call the sulphate of
lead they are bound to find in it an adulterant, not know-
ing enough about color-making to make the proper allow-
ance for the difference in the shade between that and the
medium. It is only when found in a medium chrome
yellow, where it has no business to be, that it can be
considered an adulterant.
As these light shades of chrome yellow vary, so much, it
is impossible to give the exact amount of sulphate of lead
they should contain.
Alum and barytes are. sometimes used to lighten the
tones, but principally as adulterants.
ORANGE CHROME YELLOW
Manufacture
Orange chrome yellows are the opposite of the lemons.
It has been shown that in the lemon and canary chrome
76 MODERN PIGMENTS
yellows, the change of tone from that of the medium was
due to the addition of an excess of acid in the form of
sulphate of lead or sulphuric acid.
In the orange chrome yellows, the deepening of tone
and reddish hue is due to an excess of alkali from the use
of some caustic substance. It may be obtained in many
different ways, but, after all, the difference is in the caustic
substance added to the white lead and bichromate of
potash. As stated under the lemon yellows, they must
be added to the chromate of lead, or rather to the
solutions of chemicals which are equivalent thereto,
and the whole precipitated together. The alkaline
substances mainly employed for this purpose are
caustic soda or caustic potash. The greater the quantity
of these used, the redder will be the tone of the orange
chrome yellow.
In an analysis of orange chrome yellow there will be
found, besides chromate of lead, either lime, soda, or
potash, according to which of those substances was used
before the striking of the precipitate. Therefore, accord-
ing to the quantities of the alkali, the various hues and
shades of orange are produced from the faintest tinge of
orange to those of near approach to a fiery red. There
can be no formula given of the proper amount to use for
the producing of any given shade. The manufacturers
hardly ever strike duplicates of any shade, but produce
hundreds which are not alike. They do grade and mix
many together which will give a fair average for the
standard they have adopted for the required shades of it.
Properties and Uses of Chrome Yellow
Chrome yellows of all shades and hues have about the
same general characteristics and properties, qualities and
defects. It is proper, therefore, to bunch them together,
YELLOW PIGMENTS 77
and to review them under the general head which is the
common property of all.
From their composition, one may well surmise that
they are hardly fit to be used in distemper or water-color
painting owing to the liability of their chromic constituents
of losing their oxygen and of thus becoming changed into
the lower oxide of chromium, which is greenish. The lead
also is subject to the attacks of sulphureted-hydrogen
gases which turn it into a black sulphide. It must be
easily seen by any one that great risks are run when they
are used in water colors for interiors, about the only
place where water colors can be used. When used in oil,
they are protected to some extent by the linseed oil with
which they are mixed, but in water colors there is no
protection whatever against deleterious attacks. -
In oil, however, there are but few colors which the
painter or decorator could find more useful than the
chrome yellows. While not absolutely unfading when
mixed with oil or varnish, in those vehicles the color
remains a reasonably long time before changing to such
a degree as to be disagreeably noticeable.
The range of tints obtainable from them covers the
whole field of yellows and red yellows, which are easily
made and at a very moderate cost.
There is one thing that is sure : There is nothing in the
whole field of pigment that would replace them, let them
be good or bad. It is true that some very few tones could
be made from combinations of other pigments, but at a
greatly increased cost only, almost prohibitive for general
house painting, and nearly all these substitutes would be
much more subject to fading than the chrome yellow itself.
With all their defects, and it is admitted that they have
many, they stand high above every other pigment pro-
ducing the same range of color. They will continue to be
78 MODERN PIGMENTS
used until something better is discovered to replace
them.
There are many fancily named yellow colors upon the
market, usually with a proprietary name. They are
mainly prepared for the carriage trade. Most of them
are chrome yellows of peculiar shades.
The fancy names sometimes mislead the uninitiated into
the belief that they are not chrome yellows. This belief
is dangerous, as it may lead one into using those yellows
upon work where chrome yellow should not be employed,
the workman thinking that they are not subject to the
same vicissitudes. With a knowledge of their real char-
acter, such mistakes need not occur.
Chrome yellows are extensively used for all kinds of
painting. The carriage, car, and implement trades use
them in enormous quantities as well as the house painter.
Decorators and artists are the ones who are the most
likely to have trouble with them. They are the only ones
who need have any misgivings regarding their use. They
know that even when mixed with oil, the chrome yellows
are not to be depended upon for use in interior work.
They are therefore warned to be shy of them, substituting
other yellows as far as they can.
BARYTA LEMON YELLOW
Properties and Uses
This is a distinct color from lemon chrome yellow.
It contains no lead in its composition, baryta being the
base of it. It is by far the most permanent form of that
color.
It is made by mixing solutions of neutral potassium
chromate and of barium chlorite; both solutions having
previously been heated to 100 C. It precipitates as all
YELLOW PIGMENTS 79
others made by mixing solutions having an affinity for
each other.
Unlike the lead chromates, it does not blacken by con-
tact with sulphureted-hydrogen gases, that lurking
enemy of interiors. It may also be mixed with impunity
with any of the other permanent pigments.
This yellow is of great use to decorators and artists,
more so to them than to the general house or carriage
painter, because it has not so much opacity in oil as the
chrome yellows, on account of the transparency of its
base.
It possesses one of the defects which is also common
to the chromates of lead. It loses some of its chromic
oxide and becomes greenish in hue.
Adulteration in Chrome Yellows
To detect adulteration in chrome yellow is an easy
thing. It can be done by a very simple operation, which
while it is not a scientific one, and while it gives no indi-
cation of the nature of the adulterant, is nevertheless
very effective. By its use, any one can readily deter-
mine for himself whether a given sample of chrome yellow
is pure or not. This, after all, is all that either a painter
or a dealer cares to know about a color anyway. The
test gives approximately the percentage of adulterant
contained in the color under examination. Its lameness
is that the nature of the adulterant is not revealed. That
requires a chemical analysis. As this test is applicable
to many other pigments, especially to all made from chem-
icals and which possess a recognized standard of purity
and composition, and as it is also, in part at least, appli-