127v - - - - - Founder’s earth
This is boulvene earth mixed in with dung or hairs which withstands fire, of which you must always have a large stock hanging around for dawbing the molds that you use to cast in silver and that need reheating. Those where you burn flowers or animals do not need dawbing, unless they have been left to stand once they have been reheated, and once they have been cleaned of any bones and ash that might have remained inside. And having removed the clamps, you open the two halves to see if they have any cracks. Because there is some plaster that does not harden as much in the fire as another one would. Others create crusts on the things that remain to be burned inside. And all of these are imperfections that you must avoid, either by giving the animal a bath of spirits before pouring your soaked sand, or by putting in more or less brick sand or alum, or by reheating the brick to higher temperature, or by instead of mixing in brick, mixing in broken bits of crucibles and similar things that resist fire well. Having therefore reheated your mold to burn what is inside, leave it to cool. And if it is neat and unbroken put the clamps on again, and dawb with the aforementioned earth, that is called of the founders, dust it with a bit of sifted ashes and leave it to strain. But beware not to dawb your if they are not cold. Those in which you cast silver, where nothing needs burning inside, only need, when the cast and the vents are made, to be dawbed and reheated once. Do not dawb the part of the mold in which you want to cast, but leave it uncovered like the openings of the vents.
The molds should crack at the first reheating, because then they will not crack at the second reheating anymore.
The smallest molds reheat more quickly, therefore take the ones that have finished reheating first when you cast, because you can put several in your furnace at the same time to reheat.
First light the coals in the forge, or in any other place that is close, and having placed your molds on a layer of good embers, not burning too much, in order to have a slow fire in the beginning, then add in little by little coals that are half lit to the forge.
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Earth, of the kind used to braise or solder, which is sandy clay earth. Or else clay mixed with sand after having been dried and sieved, and then composed, is good to dawb your molds. Because this type of earth melts rather than cracks. And any earth that melts cannot be lacking in this.
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Use a wire to bind.
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Dawb very thickly your molds, and if they are small, you can reheat them immediately in a good fire, even those made out of crocum.
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If the earth has hair in it, and does not crack when heated, and does not separate from the mold, the molds will not crack either and will not run when cast. Reheat them at your leisure in a closed fire and do not expose them when warm to the air.
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Dawb rather thickly in two or three layers, doing similarly at the points of the joints, so that the silver does not run out of the mold.
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Reheat in a reverberatory furnace.
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To test if your earth is good, rather than putting some on your mold, dawb in that place of the wall of the forge that is around the opening and mouth of the bellows, then turn on the fire and if it tolerates this without cracking, then it is good.