Dip a little brush into lemon juice mixed with a little lampblack and draw the design on the finely polished and prepared stone. The acid will eat little holes into it, which will take color if the lemon juice is washed away as soon as it has completed its etching, and the etched part has been dried and rubbed-in with fat color. To produce darker shadings it can be laid on the same place twice, and for lighter shadings the acid either is washed away sooner or diluted with water.
I do not doubt that a skillful chemist could invent an etching ink which would be even more perfect, and then a drawing could be washed on the stone as easily as on paper, which would mean immense advance for the art.
[CHAPTER III]
MIXED METHODS
Stone-printing has the unique property, owned by no other process, that it is possible to print relief and intaglio simultaneously. This property makes possible so many combinations of the two processes that a book might be filled with their description. I assume, however, that the reader will have understood the entire science of the new art from what I have said, and that his own reflection will tell him what methods to use or to combine for each of his purposes. I limit myself, therefore, to a few leading methods, thus giving some fundamental idea of the manipulations.
I
PEN DESIGN COMBINED WITH ENGRAVING
This can be utilized in two ways:—
When the pen drawing is finished and etched, the stone may be coated with red gum covering and the needle used to draw-in the finest lines. The printing is the same as with pen work. The second way is to make the engraved or etched part of the design first, and after the stone has been rubbed-in with acid-proof ink, cleansed and dried, to draw-in the rest with the pen and chemical ink. As soon as the design is properly dried, it is etched a little and prepared, and otherwise handled like an ordinary pen drawing.
Both ways carry the advantage that the pen can be used for those parts best done with the pen, and the engraving-tool for those parts best done with it. The latter is especially excellent for very fine and elegant script, such as title-pages, the finest strokes being made first with the needle and the broader ones with the pen.