Draw the outlines of a design on the stone in chemical ink with pen or brush, and then make four, five, or six transfers on stone plates prepared for pen work. Register marks must be on the design. Now draw-in the darkest parts on the first plate, the less dark ones on the second, the lighter ones on the third, and so on till the whole design is finished. The work is best done with a brush. One or more of the stones may be designed with crayon; but the number of stones designed with ink must be greater, in order to make the grain of the crayon designs unnoticeable.
The etching is done as in pen work. For each stone the printing-color is chosen according to the tone of its design. Of course particular accuracy is vital; but the artist should not permit the apparent difficulties to frighten him, as he will see very soon after trial that no other method produces such beautiful results.
VIII
COLOR-PRINTING WITH MANY PLATES
This method, in which the various colors are drawn on several stones, either with pen or crayon, resembles the one just described.
According to treatment the impressions will resemble a painting, a copper-plate engraving in color, or an illuminated copper-plate engraving, if the color stones are used merely to lay colors over a design already printed in its entirety in black.
The whole process is so like the preceding one that I need merely recount the colors that I have found serviceable for the purpose.
Red. Vermilion, red lake of cochineal, fine madder lake, and finally carmine if it is mixed first with Venetian turpentine before being combined with varnish, as otherwise it inclines to separate from the varnish and unite with water, staining the whole printing-paper red.
Blue. Berlin blue and mineral blue. Use only a small amount, sufficient for a few hours. These colors dry quickly, and, besides, make the varnish too tough, so that they must be thinned down from time to time with a little linseed oil. Fine indigo is very good, also a blue lake that is made of logwood and verdigris. This latter is not durable in sunlight.
I have had no success as yet with green or yellow.
Verdigris is difficult to manipulate because it smuts the stone easily and does not tolerate many mixtures. Schweinfurther green, one of the new colors, is much better in all respects, but not dark enough. Mixtures of yellow lake with indigo or mineral blue are not very durable. Golden yellow ochre with mineral blue or indigo does not produce a pretty green, and King's yellow mixed with blue is handsome but not durable. Neapolitan yellow and the newer chrome yellow with blue produce a green that is not dark enough.