When a plate, whether intaglio or relief, has been inked-in with oil color, it may be coated with one water color, or it may be illuminated with several, and then printed-off in one impression. Two parts of gum and one part of sugar are used for this. They can be dissolved with any water color. Care need be taken merely that the colors are well dried before the impression is made.

If, however, it is desired that the colors have shades so that the impressions may resemble English or French colored copper-plate prints, the process is as follows:—

Etch all shades of the color pretty deeply in any of the stippled or aquatint styles. After this, coat the stone with gum solution, that it shall take no color in these depressions. Clean off the chemical ink or the ground with oil of turpentine, and prepare the whole plate if it has not been prepared already on its surface. Then coat it with red gum surface, and into this inscribe all those lines that are to remain black. Then the color is rubbed-in and the stone cleansed so that it will be white everywhere except in the engraved parts. When it is inked-in now, it can take color there only, and the other depressions (namely the various shades of the color) will remain white because they have been prepared. Now it is necessary only to coat each part with the desired water color and it will be denser, and therefore darker, wherever there are more and greater depressions.

II
SIMULTANEOUS CHEMICAL AND MECHANICAL PRINTING

When a pen drawing is so constituted that the various lines are close together and there is no white space on it that is greater than at most one half inch in diameter, it will permit printing in a purely mechanical way without being prepared. It need merely be etched into all the relief possible without under-eating the lines. All that is needed then is a color-board or a so-called dauber, made as follows:—

A thin board of soft wood, about eight inches long and six inches wide, is planed down till it is not more than one line in thickness. Glue on it a piece of fine cloth or felt almost as large as it. Over this glue another board, of the same area as the first, but one quarter inch thick. It must be very well-dried wood, and must be made very true with the plane, or better still, by rubbing on a perfectly level stone with sand. This latter board is provided with a handle; and when all is dry this dauber is ground off true again with fine sand and oil on a stone.

Lay the printing-color on this utensil very gently and uniformly with a leather ball. Tap and pat the stone, which has first been cleaned with oil of turpentine over its whole surface, very carefully with the appliance, holding it as horizontal as possible and taking great pains to distribute the color evenly.

As compared with chemical printing, this process in itself has no advantages, but can be united with it and thus used to print three colors from one plate. This is shown by the following

EXAMPLE

Suppose that a design shall be colored black, blue, and red, and that all these colors shall be put simultaneously on one plate. Take a stone made ready for pen work, and prepare it first of all with phosphoric acid, nutgall, and gum, then wash it with water, and let it dry. Now draw-in all that is to be red with chemical ink, that must, however, contain only just enough soap to permit its solution. When this drawing is dry, etch it into pretty high relief, the higher the better. After this prepare the stone with gum, wash it, and let it dry again. Then coat it with etching-ground that has been dissolved in oil of turpentine, and draw-in all that is to be black, between and over the high etched parts. Then etch this design pretty powerfully into intaglio, after which wash with water, rinse with alum solution, and dry. When the plate is thoroughly dry, rub-in printing-color, and clean with a woolen rag dipped into gum solution and oil of turpentine. Then it will become white everywhere except in the deep lines where it will have taken color. After cleansing again with water and drying, draw-in all parts that are to be blue, using a chemical ink that contains a great deal of soap. Let this dry well, and cleanse the plate with gum and oil of turpentine again. Then it is ready for inking-in.