| Shellac | 3 parts |
| Wax | 1 part |
| Tallow | 6 parts |
| Mastic | 5 parts |
| Soap | 4 parts |
| Lampblack | 1 part |
The mode of preparation is exactly like that of the rest. The mass can be kept only in dried form, not mixed with water. The evidence that this ink is good for transfer work is that, after it has stood for some days, it still manifests stickiness when touched with the finger. If the ink does not transfer well to the stone under moderate pressure, it is too hard, and can be improved by mixing in a little butter or vegetable oil, but it is necessary to dissolve the whole mass again over the fire. If the design squashes under pressure, the ink is too soft. It is necessary to consider the temperature of the place where it is kept, and even the time of year, in order to produce the proper consistency of ink for the best transfer work.
V
HARD ETCHING GROUND
Certain methods of stone-printing demand, besides the ink, a fatty, acid-resisting mass to coat the plates. It is either the same as the material used by copper-plate etchers, or, at least, is very similar to it.
Etching Ground for stone is as follows:—
| Wax | 12 | parts |
| Mastic | 6 | parts |
| Asphalt | 4 | parts |
| Resin | 2 | parts |
| Tallow | 1 | part |
This is melted in an iron pan over a fire hot enough to melt the asphalt perfectly. Combustion is allowed to ensue till a third of the mixture has been consumed. When thoroughly cooled, it may be shaped in any desired form and saved for use.
A good surface is made also by common wax, boiled and burned till almost five parts of it have been consumed.
VI
SOFT ETCHING GROUND
For some processes there is needed an etching ground which has the property of not coating the entire surface, permitting the etching fluid to penetrate at many spots uniformly, or, if it resists the etching fluid, still so easily affected by manipulation that it will admit the acid according to such manipulation. There are two ways to make it.