(6) Take the finest powder of calcined oyster-shells, sifted through muslin; mix it up with water in which a little rice and a little white sugar-candy have been boiled; according to the quantity of rice, so will be the hardness of the crayon. The quantity of sugar-candy should not be more than the size of a filbert-nut to a pint of water.
(c) Take common pipe-clay in powder, mix it up into a paste with very strong soapsuds, made thus: - Cut up 1 oz. of white soap into small shavings; dissolve it over the fire in 1/2 pint of water; stir into the mixture while hot the powdered pipe-clay as long as you can stir it. Spirits of wine added before the powders to render the soap-water transparent, is an improvement.
(d) Dissolve 3 oz. of spermaceti in 1 pint of water, stir into it a quantity of fine-sifted or washed white colour till of a proper consistence. If to be mixed with dark powders, a very little ox-gall is an improvement.
(e) Melt 3 oz. of shellac in 2 oz. of spirits of wine; this will form a thick liquid; to this add 6 parts of pipe-clay and 1 part of oil of turpentine; grind all well together. The lighter the colour of he shellac the better; also if colours are to be added they should be ground up with the turpentine, before this is added to the rest.
The great object of attention is to procure the white chalk or pipe-clay without grit. To accomplish this, take a large vessel of water put the whiting into it and mix well, pour off the top into another vessel, and throw the gritty sediment away; repeat several times. When this is done, let the whiting settle, and then pour the water from it and dry it for use.
The compositions for white crayons and the requisite colours being prepared, and that chosen made up into a stiff paste, it is to be placed upon a smooth slab of marble slightly oiled. The paste is rolled out with a rolling pin, then cut into slips, and these are rolled into cylinders by the aid of a little flat piece of wood, then cut to the length of 3 inches each, and placed in a slow oven or drying stove to become hard.
Instead of rolling the composition, it may be forced through the nozzle of a tin funnel, this is better for the delicate colours than rolling them; when dry they may be pointed.
Chalk or charcoal is first to be sawn into 3-inch lengths, free from knots; then saw them longitudinally in narrow strips. Procure a tin trough about 4 inches by 3, and partly fill it with white wax; this being properly melted, the pieces of charcoal are to be saturated for forty-eight hours, and after draining they are fit for use. When white paste is employed, the only powdered colour to be used is lampblack, all the others are apt to get mouldy.
A good soluble colour is Prussian blue, but it is hard to grind. Dissolve it in water, then put the solution in a hole cut in a piece of chalk, this will absorb the water, and leave a great portion of the colour ready for mixing. Blue verditer is a good bright colour, but is so gritty as to require washing, as recommended for whiting. The same may be said of smalts or cobalt.
These are Cologne earth; umber, raw and burnt; sienna, raw and burnt; treated as the blue.
Crayons of these colours are generally hard; when made with powdered colours, the proper way of mixing is to dissolve the colour first in water or spirits of wine, and add it to. nearly-dry white colour, grinding the whole well together. There should be four or five shades. Madder is not used. Greens. - These may be either simple colours, as emerald green, Prussian green, green carbonate of copper; or better formed by adding the compositions of the yellow and blue crayons together. Raw and burnt sienna may also be used in combination with Prussian blue or indigo. Good green crayons are more difficult to make than those of any other colour.
Mixed or half colours are produced by an admixture of the colours required in the paste. Thus a combination of blue and carmine produces a purple; the yellows and red united form orange; black and carmine is a beautiful tint for shading; vermilion and black form a fine rich brown; green and brown form an olive colour; and red and brown a chocolate.
Each of these may be well ground in water, and when wet, mixed well with the white in different shades. These will make various reds, as well as salmon colour, flesh colour, or orange. Hematite or crocus, of itself, ground and mixed with a little size, forms an excellent crayon.
The best whites to employ are whiting or prepared chalk, pipeclay, alum white or alumina, oyster-shell white, calcined bones, etc.
Dissolve the colours, which are Naples yellow, King's yellow, and yellow lake, in spirits of wine, and mix as for carmine. The chrome yellows are not so useful, because less durable. Gamboge, Indian yellow, and gall stone are not employed, but the various yellow ochres make good crayons.
Melt together equal quantities of asphaltum and yellow wax; add lampblack, and pour the mixture into moulds for crayons. The glass should be well wiped with leather, and in drawing be careful not to soil the glass with the fingers. In trimming these crayons, if the edge be bevelled, like scissors, the point may easily be rendered very fine.