Casting the Sforza horse and recipes for casting medals
Drawing out the mould's armature, a draft epitaph, and two ways to cast medals
Folio 141r opens with a note on keeping a way to draw the crosswise beams of the armature out of the mould so the earth beneath the horse can be better rammed. A short broken line headed "Epitaph" ("If I have not been able to make... If I...") intervenes before two detailed recipes for casting medals. The first uses moistened sandy earth dusted with very fine ash of iron scale, burnt bone, cuttlefish or zinc fume so trapped air can escape, then cast in orichalc or copper-tin; the second casts the medal in scagliola gypsum mixed with clockmaker's sand.
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Withdrawing the armature from the horse's mould
Leonardo notes keeping a means to draw out of the mould all the beams that crosswise form its armature, so that the earth lying beneath the form of the horse can be better rammed. The concern is the internal support of the great equestrian mould.
Draft of an epitaph
A short heading "Epitaph" is followed by the broken, unfinished phrases "If I have not been able to make" and "If I," a personal jotting left incomplete amid the technical notes.
Casting medals in sand
Take sandy powdered earth, not too fine, moistened with salt water, salted aquavite, or distilled turpentine; fill and press the moulds, then dust with impalpable ash of iron scale, burnt bone, walnut leaves, ox dung, calcined tin, cuttlefish, or zinc fume. This veil lets trapped air escape through the coarse sand; impress the medal halfway, then cast orichalc or copper with tin.
Casting medals in scagliola gypsum
A second method coats the medal, liquid, with scagliola gypsum, then covers it with a mix of 12 parts clockmaker's sand to one of gypsum, all made liquid and cast, then re-baked. The same is done on the opposite side, greased first so gypsum does not stick to gypsum.