How to cast a large sheet of lead
A workshop recipe for melting lead on a bed of burning coals; faint square frame
A red-chalk note gives a practical recipe for making a large lead plate: level a flat surface, cover it with burning coals, melt the lead over them, then rake the coals away with a flat rake and let the metal cool. A faint square frame is sketched on the leaf. The technique belongs to Leonardo's practical metalworking notes.
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Recipe for a large lead plate
To make a large sheet of lead, Leonardo prepares a level plane, fills it with glowing coals, and melts the lead upon them; then he draws off the coals with a flat rake and lets it cool. 'And it is done.'