136r - - - - - [continued]
FROM PREVIOUS PAGE: And continue blowing with the small bellows, and the gold will turn shiny like a mirror. And once you will want to start casting, put a bit more colour in and let it rest a little, still blowing wind with both the small and the large bellows. Finally, place your mold quite red between the small molds or in a crusol full of sand quite hot and start casting. And once it will have stuck, you may, if you wish, throw it into water as gold does not get damaged like tin which breaks.
To melt gold bullion, there is no need to blow above the crusol with the small bellow.
For large works, the crusol made of sand has to be placed in a wind oven so that it is all red at the end of the furnace.
Gold, when exposed to wind or when forged becomes black. But a bit of aqua forte removes the black instantly.
If you have to forge a work made of gold on brass, as is done on small statues, put a lead sheet between the gold and the brass, and rather than anneal it and put it back in the fire, dip it in the aqua forte and it will be soft.
It is enough for the cast to be of the same thickness as the medal, that it from the middle of the cast, up to the medal. But if the medal is very thick, one should not thicken the cast as a result, because a thick cast never comes out well. It may be done large to embrace the medal as much as possible.
Enamelling thin works
Goldsmiths polish the gold leaf using a burin and then they apply the enamel onto it.