Molds for heroic size statuary can either be made of fiberglass, or a combination of silicone rubber and fiberglass. Where there is significant detail in the sculpture, silicone is the best choice. Before moving forward with making the mold, it is crucial that all detail which you wish to achieve in the final casting is in the clay. Once the molding material is applied, it is too late for modifications to the sculpture.
Applying the Molding Material to the Nativity Statues
The application of the silicone is all done by hand. It is very time consuming detail oriented work. The materials are very expensive and the consequences of a mistake can be disastrous. Once the silicone rubber is applied to the nativity statues, a hard shell or mother mold is applied over top of the silicone. The fiberglass is applied in layers. After the fiberglass has been applied, all of the sharp edges are ground off. The fiberglass mother mold, and silicone mold are then removed revealing the clay sculpture underneath.