Making and Knowing
A minimal edition of BnF Ms Fr 640

[TOC] | [diplomatic]

- - - - - folio image: 128r - - - - -

Casting with gold and silver

To cast silver and gold do always put a little ground stone of borax on the bottom of the crucible, and put your matter on it. That way the acid smoke won’t corrupt these two matters, but it is especially efficient for gold.

If you have several molds to cast, do not fill them all in one cast, because metal would get cold. Cast one after another.

When your mold start being red inside, look at the cast, if you do not see any black spot keep the same heat, and if needed, add a few half lighted charcoals with the help of pliers. However, put ground borax at the bottom of the crucible, and put silver on the top of this matter, then put your crucible into the forge, reheat your crucible which is between lighted charcoals, until it becomes red; do not blow before that. When you’ll use the bellows, make continuous longitudinal moves, tug a little bit the bellows, push and pull, that way the heat will become greater. From time to time remove your crucible out of the top of the forge with the help of your warm pliers, because if your crucible is close to the tuyere silver would cool down rather than heat up. That why it is better to put the lighted charcoals above the tuelle, three fingers far from the wall of the forge. That way the crucible is heating much better. When your silver starts melting, if you find that it is too acid by noticing that the lumps are cracking and bursting, take the size of a walnut of arsenic, and twice as much of crude tartar which is coarsely ground, that way it will heat better. Pour some of this mixture on silver in the crucible, it will get clearer. But if you have some of that sublimate crust on the metallic matter, and which looks like grains of steel, # put some of this matter in your melted silver.

at right top margin

Some people leave the silver to rest a little out of the heat before casting.

at left top margin

silver and gold which are melted with the above matters won’t become porous.

at left top margin

For gold, you need not as much crocum as stone alum.

at left middle margin

Small molds can be reheated soon. But you should oven—dry large and small molds because dampness go out of the mold with the heat. The intense heat of charcoals drives the heat from within outside.

at left bottom margin

All silver alloy make chape and all other metals too.

at left bottom margin

Silver should not be peeled off when still molten.

at left bottom margin

# Coarsely powdered.

at bottom margin

Lumps of deteriorated silver vitrify red because of arsenic and orpiment.

[continued]