137r - - - - - Casting red copper
Pure cauldron red copper, or copper of any other small works, is good to cast. To make it runny, add some sal ammoniac to it, and when you are about to cast, add a little bit of fine tin. One must cast the copper very hot into the mold, so that it is burning and very red, like gold, silver, latten, and metal. You will know that it is hot enough when it is clear and shining like a newly polished steel mirror, or like melted silver. Protect it from wind so that it doesn’t cool down too soon. Cover your cast with tow in order to prevent it from cooling down. Red copper is cleaner than latten, which smokes a lot, which prevents the metal from running. I have moulded it as a noyau very neatly, and as thin as a piece of paper. It must be very hot, white and shining like melted silver, or a mirror. I have moulded it as a noyau with the same sand mentioned above.
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It takes more time to melt copper and latten than any other metals, even red copper. It will run and will comes out well if you cast it very hot, and as thin as water.
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Remove your mold from the fire, and set it into embers, which should fill a pot or vessel.
Huile tingente to make metal runny
Take some mercury, some real sublimate of Venice, and not sublimate of arsenic, aes ustum a poix, sal ammoniac, a poix. Ground everything separately, then blend them together in a glass bottle, and put it on warm ashes. You will see that everything melts like wax, and will have bright colors. Leave to set, add a small quantity of this mixture on every metal, it will run marvelously.
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Foundry workers who make large casts to mold statues, clean the dirt from these molds with calamine, and a lot of sal ammoniac in order to make moulds clear and neat. When they want to cast they add a lot of tin. Dampness and cold could spoil their works, that is the reason why even a small source of water in the hole can damage the whole thing.
Clamps
To make clamps use flat tongs made from wire, which is reheated and bent, and hammered on anvil. Since those clamps are thinner, they burn more easily, being used in reheated molds. So use new clamps.
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