chief use in decorative work is where that effect counts
heavily.

Its main use to-day is as an ingredient in many anti-
fouling preparations for the painting of ships' hulls
below the water line, especially for the copper sheathing
placed upon the bottoms of wooden vessels. It is claimed
that barnacles and other sea pests which love to attach
themselves to ship-bottoms thereby causing in the
roughness of their uneven accumulations an impediment
that results in more friction and lessened speed when plow-
ing through the water that said pests will not attach



142 MODERN PIGMENTS

to vessels whose bottoms have been painted with it.
The poisonous character of that pigment may have some-
thing to do with that; possibly it kills them. At any
rate, their number is greatly lessened when such bottoms
have been painted with verdigris. Sulphureted-
hydrogen gases darken verdigris. It is not safe nor
suitable in any way to use it in water colors, nor is
its use in oil desirable, although when mixed in that
vehicle it is at its best.

It is poisonous, and while not of as violent a character
in that regard as that other copper-base pigment, Paris
green, hereafter described, it is bad enough in that respect
even for use in making a successful suicide. One must
exercise some caution with it.

The use of this pigment has been replaced by that of
other greens, and it is almost exclusively confined to anti-
fouling paint for ship-bottoms.

It is still used as a glazing color by a few old-fashioned
carriage painters.

MALACHITE, OR GREEN VERDITER

Properties and Uses

Under the name of malachite, a natural green
carbonate of copper has been a long time in use as a
pigment. It is mined in various parts of the world,
freed from its impurities, and treated in sundry ways.
Its formula is CuCo 3 CuH 2 O 2 . It resembles in composition
the azurite or blue verditer, but contains less of the
copper carbonate.

It is fairly permanent; but acquires a dull brownish
hue, due to the darkening of the linseed oil; is not
safe as a water color, therefore inadmissible for dis-
temper work.



GREEN PIGMENTS 143

It is so seldom used now, even by artists, that it will
be cut off with the above mention and with a parting
warning for paint students to leave it alone. It possesses
no peculiarity of tone but such as can be obtained by the
use of less dangerous pigments which can be depended
on as having greater permanency.

EMERALD, OR PARIS GREEN

Chemistry, Preparation, and Uses

Paris green is the name under which this pigment is
best known in the United States. It is a beautiful, most
rich and brilliant, transparent green, but for all its beauty,
its violent poisonous properties unfit it for the use of the
house painter, and it is only with the utmost care that it
should be employed by the coach painter as a finishing
glaze. There is, of course, nothing like it for this purpose,
and hence it is that one may be excused in taking some
risk in its application. With a great deal of care and by
the wearing of a sponge at the nostrils during its mixing
and manipulation, the danger is reduced to a minimum.
It affects some painters more injuriously than others.
Some men can never work with it without it making them
sick; such should never use it.

Its use as a glazing color in vehicles is questionable, to
say the least. For a time, while it is protected by good
coats of varnish, it may be safe enough. But when the
varnish decays, and is not promptly replaced, there is al-
ways some danger of particles of it becoming absorbed
into the human system, especially that of children.
They know nothing about the dangerous qualities of the
paint, but, attracted by its beauty, are tempted to rub
their hands over it, and become poisoned. When a
death occurs (and many have happened) from such a



144 MODERN PIGMENTS

cause, what useless regrets it must cause. Therefore the
reluctant advice is given let it alone.

This pigment is cupric aceto-arsenite, and is permanent
in oil. In water colors it is not, and will not long remain
untarnished in impure air.

SCHEELE'S GREEN

Characteristics

Scheele's green, or cupric arsenite, is another copper pig-
ment. It is an arsenite of copper, and its process of manu-
facture need not be given, as it has become obsolete. In
every respect but one, it is the inferior of Paris green,
and that one is, that, if possible, it is even a stronger
poison. As is the case of many another pigment for which
generations of painters once found some uses, its use to-
day is about nil, and it has been replaced by others bet-
ter adapted to any of the purposes to which it was put
by old-time decorators. Its place at the tail end of green
pigments is well deserved.

Owing to its frequent mention in the antiquated litera-
ture of painters of the eighteenth century, it was thought
best to list it here, simply as a warning example and to
advise against its use.



CHAPTER XIII
BLUE PIGMENTS
ULTRAMARINE BLUE
Chemistry and Manufacture

ULTRAMARINE BLUE is one of the conquests of science of
which chemistry may well be proud. As a pigment, in its
natural state it has long been known. It can be obtained
in its natural state and condition from lapis-lazuli, a
semi-precious stone. There is little danger of the natural
ultramarine ever becoming a dangerous rival of the arti-
ficially prepared ; and if it had to be extracted from the
stone now as formerly, it would hardly be employed as
lavishly as it is to-day.

Chemistry, however, revealed its composition; and ever
since, its artificial reproduction has permitted it to be
furnished at a nominal cost, and put it within the reach
of any one, whereas formerly royalty only could have
afforded its use as profusely as the average whitewasher
could do to-day.

The processes of manufacturing it artificially are well
known, but are very intricate; and until within a com-
paratively short time, this pigment was imported from
Europe. To-day the largest works in the world are
located at Newark, N. J., and produce as good an article
as can be imported from anywhere. All the raw material
that is used in the manufacture of ultramarine is cheap;
it consists of kaolin, or china clay, silica, sodium sulphate,

145



146 MODERN PIGMENTS

sodium carbonate, sulphur, charcoal, and rosin. Calcined
alum is sometimes used instead of kaolin. After heating
the ingredients together in crucibles and then cooling, a
greenish porous cake is found, which is powdered
and roasted (after the addition of sulphur) for several
hours. It requires several powderings, washings, and
dryings, also further calcinations to develop the proper
blue color.

To prepare it for use requires some careful manipula-
tion. It should be washed with water free from lime,
and requires to be finely ground. This improves the
color very much, and any soluble impurities are removed
by these washings.

Properties and Uses

The range of color is great in this pigment. It runs
from a pure blue to a purple blue, and some shades even
border upon the green, and are called green ultramarines.
However, they are not true greens, and they cannot be
listed among them. The shades that are free from purple
are accounted the best, and for the purposes of the painter
are certainly superior, as it is very easy to make a
purple-shaded tint from a blue ultramarine, but it is
impossible to make a clean blue tint from a purple
tone of the same.

Ultramarine should never be mixed with white lead
for the making of tints, on account of the sulphur it con-
tains. When it is used with a white base for that pur-
pose, zinc white is much the best, and the tone of the
tints will be cleaner and purer-looking.

Sulphureted hydrogen does not affect artificial ultra-
marine blue, neither does lime and other alkalies. Weak
acetic acid or a saturated cold solution of alum does affect
it, and in time will destroy it. It may be called a per-



BLUE PIGMENTS 147

manent pigment, as sunlight does not impair it, and it is
useful in either oil, japan, varnish, or distemper; but to
be safe, it should not be used in connection with pigments
that have acetic acid or alum in their composition. It
is always safe when used alone as a solid color or with
zinc white for the making of all blue tints.

The coach painter finds good use for it, both for the
painting of solid surfaces and for the glazing of them
with the transparent kind. As this pigment is usually
prepared, it covers fairly well, but it is inferior to Prussian
blue in this regard.

There is no particular standard whereby to judge of
the value of this pigment other than that it should be of
good blue tone, that it should cover well, and that it
should be strong in coloring matter for the solid varieties;
but the last two items do not apply to the kinds of it
which are made upon a transparent base and which are
intended for glazing.

It is also extensively used for house painting, in the
making of tints with zinc white, as these stand well, and
remain unaffected by sunlight, which cannot be said of
those made with Prussian blue.

For distemper, it is also very useful for wall work and
in decorating.

This pigment may vary a good deal without any
intentional adulteration of it. But, intentional or other-
wise, it should be up to some good sample, which can be
selected and preserved for comparison with it. There-
fore the only rule to judge it by, and the one point upon
which all would agree, is purity of its blue tone and
brilliancy.

It comes to market in its dry state in boxes containing
28 pounds. It also comes ground in oil, japan, or varnish,
as well as in water for distemper painting.



148 MODERN PIGMENTS

PRUSSIAN BLUE

History and Chemistry

This pigment really deserves to be placed first upon
the list of blues. It is probably used the most of
all the blues by painters and decorators, but, owing to its
being more fugitive in sunlight than ultramarine, it was
thought best to give it as second on the list.

Its history now dates back nearly two centuries, and
its discovery was accidental. One Diesbach, in 1714,
while he was precipitating a solution of alum to obtain a
white base for the manufacture of lakes, used some potash
that had been rectified with animal oil, and instead of
precipitating a white substance, it precipitated a blue one.
He had purchased the potash from a man named Dippel,
who, having been informed of the occurrence, traced it to
the proper cause and was able to produce Prussian blue.
The process was kept a secret as long as possible, but in
1724 it was discovered by Woodward, and by him made
public.

Its manufacture is as simple as can be, and is done by
various processes, the necessary agent being prussiate of
potash. This is obtained by fusing the potash of com-
merce with blood or other aninial refuse. After careful
preparation, it is of a yellow color. It is added to another
solution made from two parts of alum and one part of
sulphate of iron, the mixture filtered and allowed to settle.
A double decomposition ensues, in which the iron com-
bines with the potash of the prussiate, forming a sulphate
of potash, while the prussiate of iron is thrown down,
the sulphate of potash being held in solution.

On the other hand, a similar decomposition takes place
with the alum, and the superabundant carbonate of
potash is mixed with the solution of prussiate of potash.



BLUE PIGMENTS 149

By this means a sulphate of potash is formed, and the
alumina or base of the alum is precipitated. These two
precipitates, prussiate of iron and alumina, are produced
at the same instant of time and are intimately mixed,
producing a substance of a brilliant and intense blue,
the Prussian blue of commerce; this, of course, after it has
been well washed and dried.

Whatever may be the system and methods of manipu-
lation, and these may differ greatly, the equivalents of
the above must be present to produce Prussian blue.

Properties and Uses

Prussian blue is a transparent pigment of great strength
of coloring matter, capable of absorbing enormous
quantities of linseed oil. On account of the fineness of its
particles, and the still greater fineness which can be given
them by thorough grinding, Prussian blue is held a long
time in suspension before precipitating in that vehicle.

Plow and implement manufacturers use it to paint over
polished steel parts to preserve them from air or moisture,
and consequent rust. In the diluted condition in which
it is used for that purpose, it is thinned out in the pro-
portion of one hundred pounds of linseed oil to one pound
of the pigment.

One may well wonder at the strength and power of
coloring matter. A pound of it will tint a ton (2000
pounds) of white lead to a decided sky blue.

There are two qualities of Prussian blue, which may be
thus described : Quality No. 1 is very good; quality No. 2 is
good for nothing. The good should have a decided blue
tone of great clearness; that is the only tone of it worth
having. The other has a purplish or dirty blue-black
tone, and no amount of trying to doctor it up will help any.
The tints made from it are invariably sickly, miserably



150 MODERN PIGMENTS

muddy-looking, and never give satisfaction. Any tint
made from Prussian blue of good quality and a suitable
white base is very clear, clean-toned, and fairly permanent
under proper conditions. In time it acquires a slightly
greenish hue, but much of this is due, in part at least, to
the change that takes place in the oil. When, however,
it comes in contact with lime, it bleaches entirely away;
even the tints of it made with a white base will suffer.
All the alkalies have the same property, which is fatal to
it. Therefore it is unsuited for distemper work, especially
when the walls are newly plastered, and where it will come
in contact with lime which has lost none of its causticity.

Soluble and Insoluble Varieties

There are two distinct varieties of Prussian blue that
differ only in that one is soluble in water, and the other
is not. In the United States it is customary to designate
as Prussian blue, only the variety which is insoluble in
water; the soluble variety being better known as Chinese
blue or as soluble blue.

CHINESE OR SOLUBLE BLUE

Properties and Uses

Chinese blue is only a variation of Prussian blue. It
possesses all the characteristics of the former with the one
exception, it is soluble in water instead of insoluble.
On account of its solubility, it is seldom used for distemper
painting. A damp handkerchief laid over it for a minute
will extract color. It is also subject to the same vicissi-
tudes, when it comes in contact with lime and other
caustic substances, as Prussian blue.

After it has dried, when mixed with linseed oil, it is all
right, and moisture will not affect it as long as the linseed



BLUE PIGMENTS 151

oil is undecayed. Therefore for use in oil it is probably as
good as the insoluble or Prussian blue. But, as it is
identically the same thing, there is no need of cumbering
the color list so uselessly as with a separate pigment.
Prussian being the same, and furthermore, insoluble, it is
the better of the two.

As soluble blue, it has uses which are mainly in the
preparation of bluing, either in the liquid form or in a dry
powder for laundry purposes, for the preparation of car-
penters' crayons, and many other economical purposes
which are foreign to the subject matter of this treatise,
and for that reason need not be related here.



CHAPTER XIV

BLUE PIGMENTS (Continued)

COBALT BLUE

Manufacture, Properties, and Uses

UNDER the name of cobalt blue there are several
substances sold which claim to be it. The best known
is that which is made by a combination of cobalt oxide
and alumina. Thenard's blue, another variety of it,
is a cobalt phosphate on an aluminous base.

The first is the less complicated, and can be produced
by calcining a well-triturated mixture of aluminum-
hydrate and cobalt-oxide. The greatest care must be
taken that the material used in the preparation of this
pigment shall be free from iron and nickel; these sub-
stances injure the purity of tone and the brilliancy of
the cobalt blue.

Cobalt blue is a permanent pigment, unaffected by
light, moisture, or by oxygen. Cobalt can be safely used
in true fresco, as it is unaffected by lime. It can also be
safely used with any of the other pigments. It is not
as strong in coloring matter as ultramarine blue, and is
decidedly lighter in tone.

Nineteen twentieths of the cobalt blue that is offered
for sale in the United States, is compounded from a good
quality of ultramarine blue and an admixture of zinc
white, so that its shade may be lightened to that of cobalt

162



BLUE PIGMENTS 153

blue, and of which this makes a good imitation. This
imitation, in fact, is so close that even an expert would
have difficulty in detecting it. To all intents and pur-
poses, when the pigment is mixed with linseed oil, it is
fully as good as true cobalt ; but if used in distemper, it is
subject to the same baneful liabilities which have been
indicated under the heading of that pigment, and
instead of perfect security, which the true pigment would
have given, there are the usual troubles arising from
ultramarine.

It is, therefore, questionable whether it will pay the
painter to buy this as long as there is no assurance
of its purity to be had. It is just as easy to make it
as it is wanted; it is simply an ultramarine tint which
can be prepared by any one from the mixing of ultra-
marine and zinc white.

CERULEUM

Properties and Uses

Ceruleum is little known in the United States. Church,
in his " Chemistry of Paints," has this to say of it:

"When oxide of tin is moistened with a cobalt nitrate
solution and strongly heated, a greenish blue mass is
obtained, which after powdering and washing consti-
tutes one of the varieties of the pigments obtained from
cobalt and known as Ceruleum. There are other ways
of obtaining and preparing this pigment. One of these
consists in precipitating potassium stannate with cobalt
chloride, collecting and washing the precipitate and then
mixing it with some pure silica. Some samples contain
calcium sulphate or lead sulphate in place of the silica;
these are of an inferior quality.

" Ceruleum is a permanent pigment of a rather greenish



154 MODERN PIGMENTS

blue color without any tendency to the violet cast, so
noticeable with other cobalt blues when viewed by gas
or candle light. It suffers little or no change by exposure
to light or impure air, or by commixture with other pig-
ments. It is a sub-opaque, rather earthy pigment with
a moderate tinting power."

Although some painters find it useful, it can really
become so only when used where such deleterious con-
ditions exist as would injure the otherwise excel-
lent imitations that can be made of it from mixing
together in the right proportions, viridian, ultramarine
blue, and zinc white.

It is never offered for sale in America except as an
artist's color in tubes, and is likely to remain so, as the
general trade can readily dispense with it and without
inconvenience.

CHESSYLITE, OR BLUE VERDITER

Production, Properties, and Uses

Chessylite comes from the village of Chessy near the
city of Lyons, France, or rather it is named after it. It
is of the same general character as malachite, and, like
that pigment, is a copper compound, but contains less
hydrate and more of the carbonate of that metal. It
can be produced artificially, but when it is so made it is
not as permanent as the natural.

In the past century, and especially in the first half, it
was much more employed than it is now. The cobalt
blues and their ultramarine imitations have well-nigh
driven it out of the market; and as these blues, to all
intents and purposes, are non-poisonous while chessy-
lite is not there can be no good excuse for continuing
its use. It should be abandoned.



BLUE PIGMENTS 155

ROYAL BLUE BLUE SMALT

Properties and Uses

Under the above name, glass and other vitreous sub-
stances containing cobalt and of a rich blue tone have
long been known.

It is now very seldom, if ever, used, and the term smalt
has itself become diverted from its original meaning, and
is applied to coarsely powdered colored glass and also to
coarsely powdered colored sand which have been artifi-
cially colored not only in blue but in black, or anything
else. This smalt is chiefly used to sand grounds in sign
work, the grounds having first been painted in oil color
of a similar tint to the shade of the smalt thrown over
it so as to hold the latter.

Formerly blue smalt crystals were finely powdered,
washed, and the lightest-weighted particles were used as
pigment. Owing to its poor covering properties and the
difficulty in using it, it is nearly obsolete, but as it is
indicative of the origin of what is now known as Smalt, it
is well worth notice.

There are several other blues which at times have been
used as pigments either in oil or distemper. All of them
are now obsolete and their place taken by better ones.
The introduction of artificial ultramarine blue and of
Prussian blue has nearly destroyed the trade in other
blues; indigo and other vegetable blues of a similar
character being too fugitive and unstable in strong light,
and all of them are undesirable in many respects.



CHAPTER XV
BROWN PIGMENTS. UMBERS

RAW UMBER
Provenance and Chemistry

RAW UMBER is an earth pigment, and is found in every
part of the world. As may be supposed, it differs greatly
in quality as well as in composition, and its variations may
well be called numberless.

The umbers which have been found and mined so far in
America are very inferior in quality to that which has
come to be regarded as the standard by the color trade.

The umbers mined in England and upon the continent
of Europe come closer to the standard of excellence than
the American umbers do; still, they fall short.

That which is found in the island of Cyprus possesses
in the highest degree all the good points, consequently
it is the recognized standard. Some few samples are
mined in and imported from Asia Minor that are little
short of equaling the Cyprus umbers, and at one time
these were so abundant upon the market that umbers
of good quality were named after them; and even
to-day in the United States all good umbers are sold as
Turkey Umbers.

Umbers are mined like all earth pigments such as ochers,
etc., and in their natural state contain impurities which
are removed by levigations in the manner described under
ochers.

166



BROWN PIGMENTS . 157

The coloring matter of umbers is due to both iron oxides
and to manganese dioxide. To the latter is no doubt due
its excellent drying qualities in oil. The following
analysis by Church shows the composition of a good
sample of Cyprus umber, such as is imported, and is
fairly representative of what the standard of excellence
should be:

Water given off at 100 C 4.8

Water given off at red heat 8.8

Iron oxide (Fe 2 2 ) 48.5

Manganese oxide 19.0

Lime 1.4

Magnesia 0.5

Phosphoric acid (P 2 5 ) 2.1

Silica 13.7

Carbonic acid, etc 0.3

100

Properties and Uses

The color of a good raw umber should be a greenish
yellow brown, upon the citrine order when dry. It is
classed among the semi-transparent pigments. It can be
used in oil, japan varnish, or for distemper work, and in
any of the vehicles gives good satisfaction. Without
doubt it is the most useful of the brown pigments to be
found in the whole list. While umber is not so brilliant
as the burnt siennas, it can be used for a much wider
range of purposes, and it is a pure brown. The siennas,
or at least the burnt, should have been classed with the
reds, but the raw sienna is a true brown and this saves
a double classification of it.

All classes of painters regard umber as a necessity:
the house painter to mix tints from it for his drabs and
the various browns; the grainer for most all of his colors
either in oil or in distemper; the coach and car painter
for mixing many popular brown tints; the kalsominer



158 MODERN PIGMENTS

and decorator for making wall tints; the frescoer and
decorators for mixing into tints and for solid work; the
japanner for the hundreds of browns and drabs of which
it is the foundation; and the artists in either oil or water-
colors. What would they do without it?

It is prepared by paint manufacturers in oil, japan
varnish, and in distemper. For the grinding of it in paste
form in oil, it takes up nearly as much linseed oil as do