§ 67 A Simpler Method of Casting Small Figures and Reliefs
Now should the artificer wish to cast small figures in metal, they are first made of wax, or if he happen to have them in clay or other material, he makes the shell of plaster over them in the same way as for the large figures, and fills it all with wax. But the shell must be moistened that the wax, when poured into it, may set (with a hard skin) by reason of the coldness of the wet cast. Then by shaking about and agitating the cast, the wax (which is not hardened) within the cavity is thrown out, so that the cast remains hollow in the interior: the craftsman afterwards fills up the vacant space with clay and puts in skewers of iron. This clay serves then for core, but it must be allowed to dry well. Thereafter he adjusts the mould as for the other large figures, giving it its armature and placing the tubes for the vents. Then he bakes it and gets rid of the (skin of) wax and thus the vacant space remains clear so that the bronze can easily be poured in. The same is done with the low and half reliefs and with every other work in metal.