Chrome yellow

“ The Cadmium Yellows are sulphides of cadmium, and are in various shades from pale yellow to orange; they are also permanent.
Chrome Yellows are all chromates of lead, and they darken very quickly in an impure atmosphere, especially125 when used in water-colour painting. These colours are very cheap, and, at the same time, very brilliant, but they should be avoided in all cases where permanence is desirable. They also produce serious changes when mixed with other colours; for example, a green made by mixing chrome yellow with prussian or antwerp blue is notoriously fugitive in character. ”

“ The usual method is to mix black with chrome yellow (deep) , but indigo may be used instead if desired. A much brighter colour is obtained from a mixture of medium chrome yellow, Prussian blue and burnt sienna. Or the following recipe may be used: Medium chrome green, five parts; blue black, one part; burnt umber, one part. A light bronze colour may be obtained by adding more green or by using light instead of medium green. Other shades of bronze green may be got by adding a little lamp black to dark chrome green, or by taking medium chrome green and adding lamp black and a little raw umber. ”

“ The pigments are white, yellow ochre, chrome yellow light, chrome yellow medium, and chrome yellow dark, burnt and raw sienna, turkey and raw umber, ultramarine and ivory black. The greens are preferably mixed by adding ultramarine to one of the chromes. Shades are formed by the addition of the siennas, umbers, or black. Black and white, mixed to a gray, are useful in reducing the chroma of a hue. The stains should be mixed with hot water and a small amount of glue for a binder. White occasionally comes prepared with glue in its composition. ”

“ Lamp-black and Spanish brown together, produce a reddish stone color, yellow ochre, a yellow wash, but chrome goes further and makes a brighter color. It is well to try on a shingle, or piece of paper, or board, and let it dry to ascertain the color. If you wash over old paper, make a sizing of wheat flour like thin starch, put it on, and when dry, put on the coloring, for a white-washed wall, make a sizing of whiting and glue water. This precaution should always be taken before using chrome yellow or green, as the previous use of lime injures the color of the chrome. ”

“ Yellow Bronze—Lemon or medium chrome yellow, French ocher and a touch of burnt umber.
Yellow Drabs—Same as the preceding, in various proportions.
41 COLOR MIXTURES BY PARTS In this list where green is mentioned, “Universal” regular green is referred to. The yellow to be used can be chrome yellow for a darker shade, or lemon yellow for a lighter shade, although lemon yellow is to be preferred.
GREENS BY TWO-COLOR MIXTURE GOOD GREENS Some very fine greens can be made with lemon yellow and Antwerp blue in various proportions. Can be toned or deepened with black. ”

“ A dark green pigment prepared from oxide of chromium; mixed with Prussian blue and chrome yellow it is called Green Cinnabar.
Chrome Ochre. Oxide of chromium of a fine yellowish green.
Chrome Red. A chromate of lead; a durable pigment used in oil painting. (See Red Lead.)
Chrome Yellow. A chromate of lead, which makes a bad pigment for oil painting. It is very poisonous and not durable; when mixed with white lead it turns to a dirty grey. As a water-colour pigment it is less objectionable. ”

“ Let us see if we can now change our chrome yellow to chrome orange, just as we did in the glass vessel by boiling in lime-water. I place the yellow fabric in boiling lime-water, when it is coloured or dyed orange. In each little tubular cotton fibre the same change goes on as went on in the glass vessel, and as the tube or glass vessel looks orange, so does the fabric, because the cotton fibres or tubes are filled with the orange chromium compound. You see this is quite a different process of pigment colouring [Pg 84] from that of rubbing or working a colour mechanically on to the fibre. ”

“ We choose carmine for the primary red as the color which gives the brightest purple with cobalt blue, at the same time that it gave the brightest orange with chrome yellow. Thus we have chrome (No. 1) , for yellow, cobalt for blue, and madder carmine for red. These are the primaries.
Colored objects appear colored owing to their action on light. This action consists in absorbing one or more of the different colored rays which fall upon it, and reflecting the rest; and it is these reflected rays that give the color to the object. Bodies which emit light are called luminous, as the sun. ”

“ There is, of course, an immense range of greens, and the list below includes only those which are more or less frequently called for. To obtain a green, one can mix with yellow either blue or black. This forms a very good example of the difference which is obtained by mixing rays of light and pigments. The painter who wishes to make a systematic study of the subject of colour mixing is advised to experiment. He may first mix, say, medium chrome yellow with Prussian blue, then with cobalt and then with ultramarine or indigo, noting carefully the difference in the hue obtained. ”

“ Or if you don't want the color that makes, take a little reddish yellow, ochre say, and possibly a little reddish blue, new blue or ultramarine; add these, and see how it grays it and still keeps the same kind of green. This is the principle in extreme. Still, the best way would be not to try to make a green of Prussian blue and chrome yellow. It is better to know the qualities of each tube color on your palette. Know which two colors mix to make a crude color, and which will be gray, more or less, without a third. ”

“ We all went quite wild about this process, and when the workman filled in the hollowed head in the mould—it was a portrait of John Wesley—with the white preparation, very carefully, by the aid of a small spoon and a camel-hair pencil, we watched with wonder for the next development. The craftsman took a small quantity of chrome-yellow, and, having mixed it carefully with his creamy paste, poured it over the white stuff, so that in a few minutes we saw a snowy bas-relief of the great divine set on a golden-coloured background. ”

“ Zinc chrome is not much used, partly because it is expensive, partly because it cannot compete with the lead chromes in brilliance, depth of colour, and body. Still, owing to the fact that it can be mixed with sulphur pigments without change, it is often employed in the place of the lead chromes. Pure zinc chrome is completely soluble in sulphuric acid without any effervescence, but a slight effervescence may be disregarded. Any residue may be put down as adulteration, and its character can be ascertained by a few simple tests: it may be chrome yellow, barytes, &c. ”

“ Chrome is mined in Asia Minor, Greece, Canada, New Caledonia and California. Its salts are prepared in chemical laboratories.
Chromite (oxide of chromium and iron) is the only ore.
Bichromate of potash is the most important compound. It, together with chromic acid, is used in tanning soft leather. A small percentage added to steel makes it very hard and suitable for burglar-proof safes, tools, etc. Salts of chrome are used for dyes and pigments, such as chrome yellow, chrome green, etc.
Coal is one of the most important of all rocks and first among fuels. ”

“ The Prussian blue of every maker is not the same in quality, and while the character of the blue is not of the foremost importance when dark greens are being made, for light shades of green, on the other hand, it is essential to select only the best and brightest brands. In the same way the tint and quality of the chrome yellow are liable to considerable fluctuation, and it is almost impossible to ensure two lots having exactly the same characteristics, consequently the only way in which a certain shade of green can be ensured is by experimental trial with small quantities for each batch. ”

“ Liebig and Wöhler have lately contrived a process for producing a subchromate of lead of a beautiful vermillion hue. Into saltpetre, brought to fusion in a crucible at a gentle heat, pure chrome yellow is to be thrown by small portions at a time. A strong ebullition takes place at each addition, and the mass becomes black, and continues so while it is hot. The chrome yellow is to be added till little of the saltpetre remains undecomposed, care being taken not to overheat the crucible, lest the colour of the mixture should become brown. ”

“ Chrome Yellow is only useful in cotton-dyeing as a self-colour, or for conversion into chrome orange, or, in conjunction with indigo, for the production of fast green colours. The cotton is first impregnated with a solution of lead acetate or nitrate, squeezed, and then passed through a solution of sodium sulphate or lime water to fix the lead on the fibre as sulphate or oxide of lead. The 752 material is then passed through a solution of bichromate of potash. ”

“ Zinc Chrome Yellow.—Zinc chromate is inferior to lead chromate in beauty, but has the advantage of permanence. It does not blacken in an atmosphere of pure sulphuretted hydrogen, and resists very well the action of other agents. Zinc yellow may be prepared by the immediate precipitation of a solution of zinc sulphate by a solution of potassium chromate, both being boiling, but the very bright precipitate obtained in this way is not stable; on washing, it gives up chromic acid continually to the wash water, and only a pale yellow residue remains. ”

“ The colors named below, except chrome-yellow and emerald-green, are among those that when diluted will afford satisfactory contrasts among themselves and with their full colors and are recommended for use in coloring original maps.
Other pigments spread better than cerulean blue and emerald-green, but the exceptional purity of color of these two seems to warrant their use. ”

“ Now suppose I boil some of that chrome-yellow precipitate with lime-water, I convert that chrome yellow into chrome orange. This, you see, takes place without any reference to textile fibres. I will now work a piece of cotton in a lead solution, so that the little tubes of the cotton fibre shall be filled with it just as the larger glass tube or vessel was filled in the first experiment. ”

“ Saltpetre is melted in a crucible, and heated to a temperature below that at which oxygen is evolved. Dry chrome yellow is introduced so long as effervescence occurs; the fused mass appears, whilst liquid, deep black. As soon as it is in quiet fusion it is poured on a cold plate. In consequence of the rapid cooling it becomes brittle and can be easily powdered. The hot mass is broken up and boiled with water, potassium chromate going into solution. The chrome red made by this process is little inferior in brilliance to vermilion. ”

“ Chrome yellows are chromates of lead, produced by mixing dilute solutions of acetate or nitrate of lead and bichromate of potash. This makes a medium tint known as middle chrome. The addition of sulphate of lead makes this paler, when it is known as lemon chrome, whereas the addition of caustic lime makes an orange chrome of a darker color. The chromes mix well with oil and with white lead either in oil or water. They stand the sun well, but like other lead salts, become dark in bad air. ”

“ The chrome yellows, chrome greens, and Prussian blues are fugitive, whether used alone or mixed. A combination of two colors of durable nature is often subject to change of tone. Of the more durable colors for external use, the ochres, Indian and Venetian reds, burnt and raw umbers, and burnt and raw siennas may be mentioned. Zinc white, though of less body than white lead, is more delicate and durable, and should always be used in place of white lead at the seashore, where it is especially durable. The action of the salt air injures the lead. ”

“ Although they resist the sun's rays for a lengthened period, after some time they lose their original hue, whether employed alone or in tint, and may even become black in impure air. Upon several pigments they produce serious changes, ultimately destroying Prussian and Antwerp blues, when compounded therewith in the composition of greens, &c. Ranging from lemon to deep yellow, in oil, provided the atmosphere be good, the chromes may be found comparatively durable; but, on [94] the whole, the artist cannot trust to them his reputation as a colourist. ”

“ It is advisable that the painter should always have on hand the lighter shades, as although it might appear at first sight that on mixing the deeper shades with white he would get the same result, as a matter of fact there is a considerable difference. As noted elsewhere, chromes must not be mixed with ultramarine. The pale chromes change colour quicker than the darker shades. Pale chrome should never be used on fresh plaster, although orange chromes may. In the deeper shades of chrome orange red is sometimes used as an admixture or adulterant, but this is not a good stainer. ”

“ Let us have as many good colours as possible, but let the new be superior to the old, and all be distinct from each other.
As far as yellows are concerned, the palette possesses both variety and durability. Opaque or transparent, bright or subdued, deep or pale, it presents a sufficiency of permanent pigments. Most noteworthy are aureolin, the deep and 'pale' cadmiums, lemon yellow, Mars yellow, the modern Naples yellow, the ochres, orient yellow, and raw sienna. ”

“ It will be remembered that the chroma of the sphere ceased with 5 at the equator. The color tree prolongs 24 this through 6, 7, 8, and 9. The branch ends carry colored balls, representing the most powerful red, yellow, green, blue, and purple pigments which we now possess, and could be lengthened, should stronger chromas be discovered.12
(35) Such models set up a permanent image of color relations. Every point is self-described by its place in the united scales of hue, value, and chroma. These scales fix each new perception of color in the child’s mind by its situation in the color solid. ”