Better is that copper-plate method in which the resin is dissolved in highly rectified spirits of wine and poured quickly over the whole stone. By breathing on this, the resin is made to separate from the spirits and form tiny pellets, which thus make the required aquatint ground.
Both methods are better for very coarse work than for fine designs. Etching-ground, dissolved in oil of turpentine, or consisting simply of tallow and put on the stone very uniformly with a cotton ball, is much better, and produces an effect similar to wash drawing. However, it is better suited to the lighter parts of a design, because it will bear long and powerful etching only if one hits exactly the proper proportions between ground and etching fluid. Therefore, it is well, after the first tones have been etched and printed, to spatter cautiously with chemical ink all those parts that are to be darker than half-tones. Thus these dots will prepare the design so well at those places that they can withstand the most powerful etching.
V
AQUATINT THROUGH CRAYON GROUND
This is a sort of middle process between aquatint and the scraped style. It has the advantage of great speediness.
A stone that has been grained for crayon work is coated with the black or red gum ground described for the engraved method, but without previous etching, which would not do harm but is unnecessary. The outlines are drawn in with the needle very lightly, because they are to serve only to make the design visible. Those lines, however, that are not to disappear in the aquatint tone, but are to show plainly, must be cut as deeply as necessary for greater or lesser blackness. Then the stone is rubbed with color and washed with water as in the engraved method.
When it is entirely clean and dry, all the design will be black and the stone white. The design must be examined carefully, and the various gradations of shading should be separated in the mind into about eight leading classes, of which four are numbered upwards to the lightest parts, and four numbered downwards to the darkest. Everything in the category of the four dark parts now is worked strongly with chemical crayon. The purpose is to mass a number of evenly separated points over these parts of the design that shall withstand the etching fluid like an aquatint ground, between which the etching fluid may eat the stone and thus form a coarser grain than could be attained merely by rough grinding.
Then the four lighter parts must be coated with chemical ink. The very lightest parts, and all that is to remain white, must be left white on the plate and neither touched with crayon or ink.
Then the stone is etched for the first time. Following this pour clean water over it and let it dry. Then of the four dark parts the lightest are coated with chemical ink, and when it is dry the etching fluid is applied again. After washing and drying, the next lighter portions of the dark sections are coated, and so on till at last the very darkest shadows have been coated. Then a clean brush is dipped into gum solution and everything that should remain white is painted.
If a little oil of turpentine is now poured on the stone, and the crayon and chemical ink are dissolved and wiped off, the stone can be inked with soft inking-color and wiped again with a woolen rag. Then the design will look as if a black veil were over it, because the lightest parts of it and the half-shadows are not worked out at all. Wet a rag with gum solution and a little phosphoric acid, and hold it in one hand while with a fine scraper you scrape in the lights according to their gradation or grind them in with a fine stone, for instance, a slate pencil. As you scrape wipe over the design with the wet rag; and you will see exactly what you are doing as the various gradations will appear bit by bit. The printing in this as in other aquatint methods is done with soft and thin printing-color, and the paper may be more dampened than in other forms of lithography. The press needs considerable tension and the stones must be thick.