086r - - - - - [continued]
with the substance of a skillet mixed with a knob that is potin. And before that, I had so reheated my molded frame, now with the flame of my furnace, now putting lit charcoals on top of it, that it became almost red. I let it cool and cast. It came out very neatly in relief on one side & in cavity on the other, as well for the figure as the letters. It is true that the material was whitish, as almost metallic, but this was because of the potin. I made another cast with substance of skillet, alone in the same sand, but not so reheated, it did not come out well.
Since then I molded the bone of oxen feet, burned, pulverized, & sieved through a double sieve & hum fort moistened with egg glair or wine boiled with elm root. I knocked on it moderately while molding. Having undone theopened the frame, I found that the figures had not released neatly & left the molds floury—like & crumbling. I les moistened the bone sand further, so that it stuck together well in the between my fingers, and in this way, I molded neatly with a good release. And even though it seemed to me that the pulverised bone was lumpy, if there is some substance of skillet thrown in, my figures came out very neatly. It is true that I had very very reheated my frame, it withstood only one cast. I find that when a sand is so finely grounded that it renders itself dense as ceruse & even, like without knowing it to be arid, rarefied, areneux & rather spongy, that it molds very neatly, but it does not receive metal so well, as if it were porous to absorb the substance. But rather, once fat & even, it becomes porous & does not receive fine lines. I believe that the secret to cast well lies in finding a sand that receives the metal well, one for lead, the other for another, for each one has its particular one. Let it be molded slowly & scrupulously, and leave it for a few days to become compact by itself, if you have the time for this. And next, reheat it very well not all at once nor over with a large fire, but little by little, otherwise it crumbles & always has some fault. Finally, you ought to cast the copper or latten or other great metals very hot, & if it possible in large quantities of substance, which contain more heat than small quantities. It is necessary that the frame be cold, & that you cast all at once. Always lute the entrance of your frame, for the metal, touching iron or metal,
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This bone wants to be well crushed in a mortar, and does not want be reheated because it crumbles.
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