CHAPTER XX. ANOTHER AND A BETTER WAY OF CASTING.
The Florentine gold-beaters used to have another way of casting, which was called casting in the mortar,[122] for so was the furnace called in which the casting was done. You take a number of bands of clean iron[123] about half a finger thick and as broad as a thumb, and weave them into a round shape, about one & one-third cubits high, sometimes smaller, sometimes larger than this in accordance with the quantity of the work you have to cast. It must be interlaced into a domed shape to about two-thirds of its circumference, and from the iron that remains over you make four legs on which the furnace is to stand. Note that where these legs commence you must make a grating, the openings of which are wide enough to allow of one finger and a half being put through them, this serves as a base for the furnace. And the furnace itself you construct by means of fashioning a cake of earth mixed with cloth shearings,[124] the kind of earth that glass-blowers use for their furnaces. Then you take a terra cotta tile and lay it on the base of your furnace, and strew a little ash over it. On this you stand your crucible filled with as much silver as it can hold, and set to work very carefully, much as you did in the previous method. You fill the furnace with coal, light it and leave it to get red by itself, for thus left, the draught will produce a tremendous fire, and you will cast better so than if you made fire with your bellows. I must warn you too, to make your crucibles out of clean iron, for earthenware ones would easily crack; this iron should however be coated over inside & out with a paste of clean ashes about half a finger in thickness, which must dry well before the silver is put in. Some take for this solution clay mixed with cloth parings, & the one is as good as the other. For the rest you proceed with your casting just as I showed you above.