Making and Knowing
A minimal edition of BnF Ms Fr 640 in English Translation

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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.

at left top margin of folio 137r

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.

at left top margin of folio 137r

Remove your mold from the fire, and set it into embers, which should fill a pot or vessel.