| (1) | Thick linseed oil varnish | 1 | part |
| Tallow | 2 | parts | |
| (2) | Wax | 1 | part |
| Tallow | 5 | parts | |
| Linseed oil varnish | 3 | parts |
The application will be described in the instructions about aquatints, etc.
VII
ACID PROOF INK
So I name a color which has the property of resisting acid when the stone is inked with it. It is useful in many cases, and even necessary. It is well, therefore, to make a supply of it.
| 2 | parts thick linseed oil varnish |
| 4 | parts tallow |
| 1 | part Venetian turpentine |
| 1 | part wax |
All must be well melted, mixed with four parts lampblack, well rubbed down and kept in a closed tin vessel.
VIII
CRAYON
Chemical or fatty crayon is a composition intended to be used on the stone plate in dry form like Spanish or Parisian chalk. The inks described previously have the property of soaking into the stone and making it greasy where applied. The same happens if they are applied dry, the degree of their penetration and adherence merely being less.
The mixtures that may be used to make crayons are countless. Wax and soaps, however, are better than resinous materials. Therefore it is likely that the compositions here named will be pretty nearly the best.
| (1) | Wax | 4 | parts |
| Soap | 6 | parts | |
| Lampblack | 2 | parts, roasted, or better still, made as explained before. |