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

- - - - - folio image: 091r - - - - -

Molding with cuttlefish bone

Pay attention to keep the bones in a dry place, because they are very prone to dampness. If you have a small medal, divide the bone into two pieces, then smooth the two parts with a knife. And on a dry, smooth rooftile [that has been] pulverized with willow charcoal, rub and polish the two half bones. In this way, the bones soak up the willow charcoal so that the bones will come off cleanly from the cast, and will not stick to it. Then on a fake bone, that is to say a bit of smooth brick of the same width as your bone, place your medal. And then on the medal, put your bone and press it firmly with another stone of the same size. And for a second time, mold it, and instead smooth over the top with willow charcoal and blow slowly, then press as before, and it will cast neatly. If it is for a spoon handle, two whole bones are needed. Any work that is cast is brittle and prone to breaking, because the metal swells when cast, and contracts and condenses when hammered. That is why it is necessary to retrace with a chisel the cast object and in this way the metal will contract again and let it escrouir. If the piece you have to cast is in high relief, first trace the mold and the hollow with a penknife, to make a clear path for the medal and then cast it. And if the medal has two sides

at left bottom margin of folio 091r

Rather than casting, heat the bones only to make them lose the coldness and wetness.

at left bottom margin of folio 091r

When the lead gets too hot, it calcinates.

- - - - - folio image: 091v - - - - -

Because the two bones are joined, cut around them with precision, and make notches in different places which cross through where the two bones are joined, so as to recognize the place where they were first joined. Or with little shards of wood, you can also pierce the bones, or coat the joints with clay, and leave it to dry. Compress between them it with your two hands in between your knees; and do not use a normal press, otherwise the bones will break. Mold at your leisure two or three times, until you can see that it has the design come up and is well imprinted. And on each occasion rather than putting the piece straight back in the mold, smooth with willow charcoal because it helps it to come out easily. Once you have cast, rub your medal with oil and willow charcoal with a brush, to make it dull. Take care that your medal is not greasy or oily when you cast it in cuttlefish bone. Once you have cast, leave it to cool rather than taking the medal out straight away, because when one takes it out hot, some bone will come away with the medal. Cast at medium heat, which you will recognize because the bone should stay almost white. But when it is too hot, the bone becomes brown. The proportion of lead and tin is equal, one to the other. If the piece is difficult to cast, and composed of various pieces, cast it with a forked pattern, of three or four grooves, and make and make these grooves where the metal is the thickest. Also make these grooves around the medal and directly on the head because this attracts the metal and will fill the figure best. Lift your boxmold a little, once you cast, and in this way you will be able to make several clean casts. Tin that is too hot burns the bone which becomes damaged. Moreover, having come out of the mold hot , it risks breaking.

Figure Figure