Some to make it flow neatly, put half metal and half copper. Others take a part of potin and a part of copper latten. Others take a part of latten from candlesticks and a part of latten from a basin. And among basins, the latten from larger ones is harder than that from skillets because the material needs to be softer in order to give them such a small circumference. From the large ones, from which they take the more ample circumference, the harder material can be taken. The harder the latten, the better it flows and the neater it casts, but it must be cast very neat hot. As one wishes to cast, one puts lead on the material, which makes it flow and run and goes up in smoke and be careful that the mold does not get damaged. And if you want to cast pieces on fire, mix more rosette than latten, so that it is less brittle. The crucibles used to melt metal should be better than those used by glassmakers because glass is not as heavy as metal. And in this instance, the crucibles need to be luted with earth and crushed glass.