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

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Sand work

Some excellent sand is found for use with lead, tin and copper close to the hill of Pech—David, close to Toulouse. It should not be reheated much because drying out suddenly, it will lose its binding properties and retract [?] at the first inflow of metal, which makes the work become rough and unclean. It is much better to reheat it from a distance, instead of with a straw flame, which generates grime. Instead of filling the frame, you can use finer sand which you will have in a very thin cloth, and polish the medal and then the wet sand that you will put over it, which has more body, will grip it.

at left top margin of folio 081r

Tallow makes things fill with bubbles

at left top margin of folio 081r

Mercury stops the burning when one wants to cast. Allow the metal lead to flow, but if it is pure, it needs to be cast quite hot so it flows and vents.