# Cyclopedia of Painting/Pigments

PIGMENTS.
Names of pigments are not always synonymous with the colors. Dutch pink is yellow, verditer is blue, lake is not purple-blue always, but sometimes green, yellow, brown, etc., or it may be found as a pigment color, with a chalk base, or body.
Before proceeding to describe the actual method of mixing, a few general remarks on colors may be given. White lead is used for the base of paints, because that pigment possesses greater covering properties, or body, as it is technically termed, than any other. Zinc white may be used for a base under certain conditions, and color mixed with it will not be so likely to fade as when mixed with lead. The tendency of zinc white, however, to chip and crack renders the addition of lead necessary in some cases. When practicable, the natural earth pigment should be used for tinting purposes in preference to those which are manufactured. Raw umbers, raw siennas, etc., will be found to last longer than burnt umbers and burnt siennas. As a rule, burnt umber should not be used for outside painting, but the required shade should be obtained by mixing lamp black and an oxide color, such as Venetian red.
Common colors include lamp black, red lead, white lead, Venetian red, umbers, and all other common ochres, such as greys, buffs, stones, etc. Superior or ornamental colors include bright yellows, warm tints, blues, mineral greens, etc.
In compounding pigments for painting, there is yet a further matter requiring some little consideration by the painter. All blue pigments are not chemically suitable for mixture with yellows or reds, nor all yellows with reds; in fact, a knowledge of the chemical source and affinities of pigments is almost a necessity to the painter and decorator. ​As the most brief and simple way of aiding the student, it will be well to mention those ordinary pigments which it is usually advisable not to mix together.
For mixing with oil color paints, chrome is an undesirable pigment, and it is particularly to be avoided when compounding greens from Prussian or Antwerp blues, which latter colors it would eventually destroy. In such an instance, for common use the best substitute for the chrome would be bright yellow ochre, or, as it is often called, yellow paint. Raw sienna can also be used with the above blue pigments without much detriment to either. In any case where a bright mixed green is absolutely necessary the lemon chrome can be used in conjunction with good ultramarine blue or indigo.
In compounding the secondary color of purple from blues and reds, there is less danger of trouble arising. The best and purest is obtained by mixing ultramarine with madder lake, which is a beautiful crimson and transparent permanent pigment, while lakes derived from cochineal are unstable, ultramarine and vermilion will also answer. Prussian blue and vermilion give very deep purple, which may be lighted up with white. For common purposes, the cheap purple brown is most useful, if required full in strength, but if lighter and pure tints are wanted in oil or distemper, ultramarine blue and vermilion, or, for cheapness, Venetian red, is necessary. Prussian blue in water would not suit so well, but indigo could be used if cost is not a consideration.
The remaining secondary, orange, is not a color very much called for. Orange chrome or orange red is a bright opaque pigment, but otherwise like all the chromes, not a commendable article. Burnt sienna is a very opposite pigment in both nature and source. It is semi-transparent, reliable, and permanent, and is, when of good quality, a remarkably strong stainer, like Prussian blue in this respect. In compounding orange color, the reds and ochres already mentioned are usually bright enough, yellow ochre and Venetian ​red, or raw and burnt sienna together, give with white lead, a good and serviceable variety of permanent orange and salmon tints.
The compounding of the third division of material colors, the tertiary, from either of the two secondaries, is a subject that need scarcely here be dealt with. The painter who works at this subject will soon find those secondary pigments of orange and green which produce the tertiary citrine, whether bright or sombre, such as occasion requires. Of the remaining tertiaries, russet and olive, prepared from the secondaries purple and orange, purple and green, respectively, there is a good supply in the form of simple pigments. Notwithstanding, therefore, the necessity and advantage of the painter being able to obtain any color by the admixture of the three primaries, it is always most desirable to use a simple article of the desired color when it is to be had.
In the actual mixing of paints, it must not be thought that there is any one way that is exactly right while all other methods are exactly wrong. Every painter has his own peculiar way. In nearly all cases, the simplest plan is to use pigments ground in oil instead of dry powders. With a pallet knife break up the lead rather stiff, adding a little oil. Thin down each paint until it is rather stiffer than the whole will be when ready for actual application, or if dry pigments be used, add a little oil, and thoroughly mix. The lead, zinc, or other base being ready, add some pigment, and well stir. If several pigments are required to produce the tint, be sure to add only one at a time, and take great care that each is thoroughly mixed before the next one is added. As a further precaution, it is well not to add the pigment all at once, but to do so a little at a time. When it is certain that a thorough admixture has been effected, the next pigment may be added a little at a time. It is well to remember that some pigments, such as Prussian blue, are very strong, and the addition of too much will spoil the job. It is easy to add a little more, while it is impossible to take any out. A little ​precaution in this respect will save much trouble, and although it takes longer to mix the paint, it is the much safer plan. Of course, a practical painter who is used to mixing paints can add the necessary amount of colors without taking these precautions.
Having mixed the paint, add as much driers as may be necessary, taking care not to use too much. Then the paint should be strained through a fine wire strainer. It is well to mix up enough of the paint in one batch to do the whole of the job in hand, so that there may be no trouble or waste of time in matching tints. Paint mixed in cold weather is very likely to give unsatisfactory results, because the oil will stiffen and be more difficult to form into a perfect admixture. To remedy this, a gallon or so of the oil should be heated, and this poured in will warm up the paint, and prevent it pulling when applied, and so avoid the unnecessary force required to draw the brush along.
In preparing oil paint, the first question to be considered is the nature of the surface to be painted, whether of wood, stone, or metal, and to what degree it is absorbent; second to this must be remembered the conditions and position of the work, such as refer to expense, durability, and drying qualities; and lastly, to bear in mind the all-important matter of appearance and color, whether the paint is for the first or last coat.
The quantities of driers, oil, and turpentine required to bring 100 pounds of white lead to the consistency of paint is a matter that must be varied according to the conditions of the work it is required for. In summer-time, 1 pound of good driers to 14 pounds of white lead is ample for out-door purposes; in winter-time, 1 in 10 would be best. The quantity of oils required would be about 1+$^1$⁄$_2$ gallons for 100 pounds of lead. The proportions of linseed oil and oil of turpentine it is advisable to use depends entirely, upon the purpose it is intended for. With reference to the question of boiled or unboiled oil, it should be remembered that both ​oils are glossy when applied in sufficient quantity, boiled linseed oil has more body, and is more brilliant than raw linseed oil, raw linseed oil is lighter in color, and is not so liable to blister as boiled linseed oil, boiled linseed oil dries quicker than raw linseed oil.
To mix 1 pound of ordinary oil paint, take about 8 ounces of pigment the desired color. White lead for white, light grays, pinks, cream, etc., Venetian red or vermilion for red, and so on, according to the color desired. Add to this about 2 ounces of liquid driers, then make up to 1 pound with either linseed oil alone or oil and turpentine in equal parts. Remember, the more oil, the more driers is advisable, but never less than 1 part driers in 8 or 10 of entire bulk. If only small quantities of paint are wanted, that sold ready mixed would be cheapest and would do for ordinary inside work. A single pound could not be made cheaply, and some of the colors, bright red, for instance, could not be made at twice the retail price.
The ingredients for making about 40 pounds of best paint for indoors, tinted to a French gray color, would be 28 pounds of genuine white lead, 3 pounds of patent driers, about $^1$⁄$_2$ gallon of raw linseed oil, and 1 quart of turpentine. Mix up the lead and driers with a broad stick to the consistency of a thick paste, using linseed oil. If all is to be tinted one color, for French gray add a little ultramarine blue and either a little Venetian red or lamp black. If a warm gray is wanted, add the red, if a cool metallic tint, add the black. The ultramarine can only be bought in powder; mix this well with a little oil before adding it to the paint, the other colors can easily be obtained ready ground in oil. For first coating on new plaster, nearly all linseed oil and a little driers may be used, very little lead. This will stop the suction of the plaster. As a rule, new plaster requires four coats to get a good surface.
White Lead. The pure product dissolves completely in dilute nitric acid, as well as in potash and in soda lye. When ​exposed to the sulphuretted hydrogen or moistened with ammonium hydrosulphide it turns brown or black, whereby it is distinguished from zinc-white. When heated with the access of air it yields its carbonic acid, and at 572° Fahrenheit passes into lead oxide and finally into minium. When digested under pressure with carbonated water for some time, the water may contain 0.22 drachm of lead per quart. The difference in covering power is due to the form, size, density and composition of the smallest particles. The white lead obtained by the French or precipitation process is looser, of a coarser grain, and possesses less covering power than the product obtained by the Dutch or German process, which is denser, of a finer grain, and never crystalline, and, though of a greater specific gravity, requires less oil.
When exposed to the light and air, white lead is fairly permanent and will resist exposure to normal conditions for a great length of time; on the other hand, when exposed to the fumes of sulphuretted hydrogen and other sulphurous gases, white lead turns brown or black through the formation of the black sulphide of lead. The production of this body is more likely to occur in large towns, where great quantities of gas are used for lighting and other purposes, which usually contains some sulphuretted hydrogen or other sulphur compounds.
White lead can be mixed with all pigments except those which, like cadmium yellow, ultramarine or King's yellow, contain sulphur, such pigments sooner or later causing the formation of the black sulphide, and thus bringing about the discoloration of the pigment or paint.
In commerce white lead is found in two forms, as a heavy white powder, having a specific gravity of about 6.47 and weighing about 180 pounds to the cubic foot, or as a paste containing about 8 per cent of the linseed oil. To make the latter, the dry white lead is first mixed in a mixing mill with about 8 to 9 per cent of its weight of raw linseed oil; it is then run through a grinding mill several times to ​ensure a thorough mixture of the oil and white lead. This form is much liked by painters, it being more readily miscible with oil and turpentine to make it into paint.
In order to obtain a cheaper product, white lead is frequently mixed with barytes which is distinguished by its white color and great specific gravity. The mixture is often effected in fixed proportions and for certain varieties of white lead, which are known by special names or numbers, remains unchanged. Thus Venetian white consists of equal parts white lead and barytes, Hamburg white of 2 parts barytes and 1 part white lead, Dutch white with up to 75 per cent barytes. The so-called Kremnitz white is a pure white lead. It is produced by placing trays containing a paste made of litharge and either acetic acid or lead acetate upon shelves in a chamber built of brick or wood. When the chamber is filled carbonic acid gas is sent into it and is absorbed by the lead oxide present in the paste.
Zinc White or Zinc Oxide has, in recent years, made great advances in popularity among painters. Compared to white lead, it is as white to yellow. It is indeed beautifully white, very fine, and easily worked. The whiteness is of importance in mixing paints, as the purity of color is retained, while when mixed with lead the yellowish east to some extent destroys the purity of the original color. The fact that oxide of zinc is non-poisonous is a point in its favor of very considerable importance. It is claimed that painters who take care to wash themselves frequently and to take every precaution, are not likely to contract lead poisoning. As a matter of fact, the best of painters are at times careless, while in the rush of work, it is often impossible to take the precautions required. The most important quality of zinc white is its extreme durability.
Properly mixed it will last, at a moderate estimate, twice as long as lead, especially in large cities where the air is impregnated with sulphur derived from burning coal. Lead, in such circumstances, turns yellow or black and quickly ​decays, and some places, such as stables, where sulphuretted hydrogen abounds, it is useless to paint with white lead, and if zinc is used these disadvantages are avoided.
Zinc white has a very good body, better, or as good as white lead. If a proper comparison be made, and if both be thinned out to a consistency suitable to be applied by brush, it is true that zinc white will apparently not have so good body as lead, but it will spread much farther. If an exactly equal quantity of lead and zinc are both painted on an exactly equal area, zinc will cover a little better than lead. In this state, however, the consistency of the zinc paint would be rather too thick. It is easily thinned, more so, comparatively, than the lead would be.
A consideration of these facts will show the practical painter that less zinc than lead will be required to perform a good job, and when the durability is also taken into consideration as well as the beauty, it will not take long for him to make up his mind as to the superiority of zinc.
There is one point, however, about its use which must be explained. Zinc white is, when compared with lead, quite light in weight, or, in other words, its volume is much greater than lead. Now, it being an entirely different product, it must not be treated in the same way as lead would be. The painter, perhaps, takes some zinc, mixes it with raw oil, with a liberal amount of patent driers and a more liberal dose of turpentine, and then he grumbles because it does not show up to advantage. What he does is to destroy its inherent good qualities. To repeat then, zinc white must not be treated in the same way as white lead.
The proper way to treat zinc white is to mix it with refined boiled oil, no driers should be used, and only just sufficient turpentine to bring it to the required consistency. Being pale, it does not destroy the whiteness of the zinc, while it certainly aids considerably in drying. In fact, it is the only practical drier for the zinc, far better than patent driers, or any other goods of the kind. It is paler than raw ​linseed oil, and hence it does not destroy the most delicate tints, however light.
PIGMENTS LIABLE TO CHANGE UNDER THE INFLUENCE OF SULPHURETTED HYDROGEN, AIR AND MOISTURE.
* Yellow. Chrome yellow, mineral yellow, Naples yellow.
* White. Cremintz white, flake white, pearl white.
* Red. Red lead, purple led, iodine scarlet.
* Green. Verdigris, Scheele's green, emerald green, mountain green.
* Blue. Prussian blue, Antwerp blue.
* Orange. Orange chrome.
PIGMENTS LITTLE LIABLE TO CHANGE UNDER THE INFLUENCE OF SULPHURETTED HYDROGEN, AIR AND MOISTURE.
* White. Zinc white, constant white, tin white.
* Red. Vermilion, red ochre, Indian red, madder lakes.
* Yellow. Yellow ochre, barium chromate, zinc chromate, aureolin, raw sienna.
* Green. Chrome green, cobalt green.
* Blue. Ultramarine, smalt, Thenard's blue.
* Brown. Vandyke brown, raw umber, burnt umber, manganese brown, sepia.
* Black. Ivory black, lamp black, Indian ink, graphite.
* Orange. Orange vermilion, burnt sienna.
PIGMENTS LIABLE TO DETERIORATION WHEN IN CONTACT WITH WHITE LEAD, CHROME OR OTHER LEAD PIGMENT.
* Yellow. Yellow orpiment, king's yellow, Indian yellow, gamboge.
* Red. Iodine scarlet, cochineal, carmine.
* Orange. Golden antimony sulphide, orange orpiment.
* Green. Sap green.
* Blue. Ultramarine.
PIGMENTS WHICH ARE LITTLE AFFECTED BY HEAT, AND WHICH MAY BE USED WHEN THE MATERIAL HAS TO STAND FIRE.
* White. Tin white, barium white, zinc white.
* Red. Red ochre, Venetian red, Indian red.
* Yellow. Naples yellow, antimony yellow.
* Blue. Smalt and royal blue, ultramarine.
* Green. Chrome green, cobalt green.
* Orange. Burnt sienna, burnt ochre.
* Brown. Burnt umber, manganese brown.
* Black. Graphite, mineral black.
COLORS THAT MAY BE USED WITH LIME.
* White. Permanent white, baryta white, gypsum, zinc white.
* Red. The vermilions, light red, Venetian red, Indian red, madder lakes.
* Orange. Cadmium, orange chrome. Mars orange, burnt sienna, burnt Roman ochre, light red.
* Yellow. Aureolin, cadmium yellow, lemon yellow, Naples yellow. Mars yellow, raw sienna, yellow ochre, Roman ochre, transparent gold ochre, brown ochre, Indian yellow, Oxford ochre.
* Green. Oxide of chromium, transparent oxide of chromium, viridian, emerald green, malachite green, verdigris, terre verte, cobalt green, chrome green.
* Blue. Genuine ultramarine, artificial ultramarine, new blue, permanent blue, cobalt blue, cerulean blue, smalt.
* Purple. Purple madder. Mars violet.
* Brown. Bone brown, bistre, Prussian brown, burnt umber, Vienna brown, Vandyke brown, Cologne earth, asphaltum, Cassel earth, manganese brown. Citrine. Raw umber, Mars brown.
* Blacks. Ivory black, lamp black, blue black, charcoal black, cork black, Indian ink, black lead, drop black, plumbago.