087r - - - - - [continued]
In order to mold well, one ought in a big frame several medals together, for when there is a lot of substance, & the crucible is almost full, it heats more, & then, if one medal does not come out well, the other will be good.
It is better to melt in a bellows furnace than in a four à vent, because it gives a more vigorous heat. It is true that latten melts well in the four à vent, because it is easier to melt than copper, being more brittle.
Some of the founders have this superstition, that only three days a week are good for melting, namely Tuesdays, Wednesdays Thursdays, and Saturdays. The others, for them, are unlucky.
When you mold, do not knock excessively on the medal, which is in the sand, because it prevents it from releasing very neatly, & shakes loose the mold.
Take heed also that the sand does not surpass the edges of the frame, for it makes the molded medal higher than the cast, & in this way, metal will never enter the mold. Therefore, always make sure that the surface of your casted object directly lines up with the mold, and to make this effect, if you wish, put a lump of carton of whatever thickness you wish.
Founders, in order to prevent their large cast works from becoming porous, are careful to well reheat their molds. And to know if they have been reheated enough, they knock against it with their finger, & if they ring like a pot, then they are.
To cast their canons neatly, they mix their earth with some fine casting sand, if they can get any.
Sand from Thoulouse
The usual bo good one is the one which is found in a vineyard near Puy David, but the one which is most excellent is the one is from Touch, near Sainct Michel & near Blagnac, in a vineyard that is high up. The latter is thinner, & a little fatter than the other, & better for small works. It does not want to be too reheated.