Permanency.—It should be stated what is meant by a permanent color. There is no color which is not to be influenced in some way. The most sound of pigments will change if the conditions favor the change. When we speak of a permanent color, we mean only one which under the usual conditions will stand for an indefinite time. By which is meant ordinary diffused daylight, not direct sunlight, and the ordinary air under normal conditions. If there be direct sunlight, you may expect your picture to change sooner or later. But one does not hang his pictures where the sun's rays will fall on them. If there is any exceptional condition of moisture in the air, the picture may suffer. Or if from any cause unusual gases are in the atmosphere, or if the picture be too long in a dark, close place, the picture may smother for lack of fresh air, just as any other thing, plant or animal, which depends on normal conditions of atmosphere would do.
Let us say, then, that what we mean by a permanent color is one which will stand unchanged for an indefinite length of time in a room which is of the usual condition of temperature and freedom from moisture, and where the light is diffused, and such that the direct rays of the sun are not on the picture often, or to any great extent. Cold will not hurt a picture if the canvas is not disturbed in that condition, but to bend or roll it while it is very cold will of course crack it, and sudden and extreme changes of temperature may have the same effect. In other words, some care must be used with all pictures as a matter of course.
COLOR LIST
Whites.—Zinc white is the only permanent white, but it lacks body and is little used. The lead whites, flake, silver, cremnitz, will darken in time, and will turn yellow with oil, and may change with or affect change in other pigments. The zinc white is liable to crack. We have no perfect white, so practically you may consider the lead whites as permanent enough, as other painters do.
Yellows.—Cadmium is permanent in all three of its forms. It is a color the permanence of which is of great importance; for its brilliancy is quite essential to modern painting, and if it were not permanent, the picture would soon lose the very quality for which the color was used. The chromes, which are of similar color-quality, are less permanent, and are almost sure to turn to a horny sort of yellow; and a green, which by their use was bright and sparkling, will, in a few months, lose its freshness—this cadmium will not do. Cadmium is also to be preferred to chrome, because it is of a much finer tonality. Greens and yellows made by the admixture of chrome are apt to be crude as compared with those in which cadmium was used.
Strontian yellow is a permanent and most useful light yellow, much to be preferred to all other citron yellows except the pale cadmium, and can be used in place of that if necessary. They are both expensive colors of about the same cost.
Naples yellow was a very prominent pigment with the older painters. It is still very much used, but in the simplification of your palette you may as well leave it out, as you can get the same qualities with cadmium and white. It is durable and safe, but adds another tube to your palette which you can well dispense with.
The ochres are among the oldest and safest of pigments. You can use them with any colors which are themselves permanent. There are several of them,—yellow ochre, Roman ochre, transparent gold ochre, and others. They are all native earths, and though they contain iron, they are sufficiently inert to be thoroughly sound colors.
The siennas, burnt and raw, are like the ochres, native earths, very old and permanent colors, and may be used anywhere.
The umbers are in the same class with the siennas and ochres. They should all rank among the yellows. The browns of umber and sienna will make greens with blues.
Indian yellow and yellow lake should both be avoided as fugitive.
Aureolin is a rich, warm golden yellow of the greatest permanence, and should be used when Indian yellow and yellow lake would be used if they were permanent.
Reds.—The vermilions are permanent when well made. They are of great body and power, as well as delicacy. They are of two kinds,—Chinese, which is bluish in tone, and scarlet and orange vermilion, which have the yellow quality. Both kinds are useful to the palette because of the practical necessities of mixing.
Light red is a deep, warm red earth, made by calcining ochre, and has the same permanence as the other ochres. It is a fine color, of especial value in painting flesh, and mixes with everything safely.
The madders—rose, pink, purple, and madder carmine—are the only transparent reds which are permanent. Whatever the name given them, they should not be confounded with the lakes, which are absolutely untrustworthy. By reference to the plates you will see that the madders are practically the same as the lakes in color when first used. But the lakes fade and the madders do not. The madders cost about twice as much as the lakes; but you must pay the difference, for the lakes cannot be made to stand, and you must have the color. There is nothing for it but to pay twice as much and buy the madders.
The lakes—scarlet, geranium, crimson, and purple—are all bad. The madders and lakes are all slow dryers; but unless carelessly used with other colors which are not yet dry they need not have a bad effect on the picture from cracking.
Distinguish the so-called madder lakes and the lakes; and between carmine, which is a lake, and madder carmine, which is a madder.
Blues.—The ultramarine of the old masters is practically unused to-day because of its cost. But the artificial ultramarines, while not quite of the same purity of color, are equally permanent, and are in every respect worthy to be used. Of these the brilliant ultramarine is the nearest in color to the real lapis lazuli. The French ultramarine is less clear and vivid, but is a splendid deep blue, and most useful. The so-called permanent blue is not quite so permanent as its name implies, but permanent enough for practical purposes.
Cobalt blue and cerulean blue are two pigments, one very light and clear, the other darker, which are made of the oxide of the metal cobalt. In oil they are permanent, and do not change when mixed with other colors. For delicate tints, when the tones are to be subtly gray yet full of the primary colors, the cobalts are indispensable. You should always have them on hand, and generally on your palette. Cerulean blue is of less importance than the other, but in very clear, delicate blue skies it is often the only color which will get the effect.
Prussian blue possesses a depth and power and a quality of color which make it unique. The greenish tone gives it great value in certain combinations as far as its tinting effect is concerned. But it is not reliable as a pigment. It changes under various conditions, and fades with the light. It is not to be depended upon. Antwerp blue, a weaker kind of Prussian blue, is even more fugitive. It is a pity that these colors will not stand, but as they will not, we must get along without them.
Indigo has a certain grayish quality which is useful sometimes, but it cannot be placed among the even moderately permanent colors.
The blacks may be classed as blues, because they will make green if mixed with yellow. Considered as blues, they are, of course, dense and negative, and should not be too freely used. But they are all permanent. The only ones we need speak of are ivory black, which has a reddish cast, and blue black, which is weaker, but lacks the purplish note, which is often an advantage.
Greens.—We