Chapter 9 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.