Traditional method of producing molds for metal sculpture and other castings .
It requires a positive, a core made of refractory material and an outer layer of wax. The positive can be produced either by direct modeling in wax over a prepared core (direct lost-wax casting), or by casting in a piece mold or flexible mold taken from a master cast. The wax positive is invested with a mold made of refractory materials and heated to melt the wax, leaving a narrow cavity between the core and the investment. Molten metal is poured into this cavity. When the metal has solidified, the investment and core are broken away. See also investment casting .