Wax and plaster are usually intermediates, the former for delicate surface modelling of work to be translated into bronze, the latter for making casts. The master then adds the finishing touches. Bronze is an alloy largely or exclusively of copper and tin, used since about 2000 BCE . Just as attractive to sculptors was the material's ability to take fine detail. Colossal statues, like their smaller fellows, would conveniently be cast in sections, and then fitted together, with drapery or armour perhaps concealing the joins.
Ordinary casting can be a copying process, often for transferring work in one medium into another.
Lost-wax casting entails making the sculpture in wax, supported by some central core or armature. The wax makes possible very fine modelling, faithfully taking every hint of the artist's hand. The finished work is bundled up in a fine plaster package, suitably adorned with vent-holes, and heated. The wax escapes, leaving its negative impression on the plaster. Molten bronze is then poured in, taking the place of the wax, and faithfully adopting all its surface features.