140v - - - - - [continued]
to engrave on silver & copper with aqua fortis. With this wax too, one fills the cavity of a relief, & then casts in this cavity, with moistened sand, which immediately takes the relief very neatly. And then you can cast its cavity on it in copper, gold, and silver, and make really singular seals.
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Seals
To cast in sulfur
To cast neatly in sulfur, arrange the pith of bread under the brazier, as you know. Mold whatever you want into it & let it dry & you will have very neat work.
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Try sulfur passed through melted wax, because it will no longer ignite & and make eyelets.
Molding and shrinking a large shape
Mold it with the pith of bread just out of the oven, or like that aforementioned, & in drying out it will shrink & consequently so will the medal that you will cast. By these means — lengthening out or enlarging the imprinted bread — you can vary the shape & from one face make several different ones. The bread straight from the oven is best. And the one which has been heated twice contracts more. You can cast sulfur without letting the imprint on the bread dry, if you want to cast it as large as it is. But, if you want to let it shrink, let it dry to a greater or lesser extent.
Casting of lead and tin in plaster
If you want to cast any flat medal or any animal that is not very heavy, and that must not be burnt inside the mold, you can indeed cast in mixed plaster & brique, as above; and not in plaster alone, because it contracts too much feeling an ardent fire if it is not so mixed. But, with the brick, it holds well. However, take heed to dry out your mold at length & on a slow fire & with patience, because there is no need to reheat it. But when your work is of flowers or other things that want their mold to be reheated & set ablaze, mix the plaster with stone alum & even with crocum. I have molded in very neat plaster & brick & it has sustained several castings.
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I tried both plaster & brick alone and molded en noyau with like the others. My mold was very clean, having lightly oiled & rubbed my medal with spirits. I made my casting wide at the entrance, narrowing it as it goes along until it reaches the medal which is very thin. I notched the casting which embraced the medal well. I dried the mold out well on a slow fire & finally, I heated it well without turning it red. I let it cool in such a way that I could hold my finger to it without burning myself. I made a line of 4 ℥ of tin, & ix deniers of lead. I cast it red, and it was quite good and beautiful. Afterwards I put xii deniers of leadon top of 4 ℥ of tin. It is very good & beautiful.
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When there is nothing to burn in the mold, it is not necessary to reheat it for lead and tin. But for flowers and other things that must be burned, it is.