Making a Sculpture
A process called lost-wax casting is used to make metal sculptures. Different stages of the process depend on physical properties of wax, clay, and metal. Wax can be carved and molded. Clay becomes brittle when baked at a high temperature. When melted, most metals form homogeneous mixtures, which can be poured into molds. Interpreting Diagrams Why is it important that wax has a low melting point?
Preparing clay molds
This artist from Nepal in southern Asia is preparing molds for lost-wax casting. She is applying layers of clay to a wax model.
1 Wax model A wax model of the sculpture is built up around a clay core. Wax is used because it is soft enough for carving fine details, but hard enough to retain its shape at room temperature.
2 Clay mold Clay is applied to the wax model in layers of increasing coarseness, and left to dry. The inner, finer layers capture every detail of the sculpture in a smooth mold. The outer, coarser layers (clay mixed with sand) provide strength.
3 Melting wax The clay-covered wax model is then baked in a kiln. Because wax has a low melting point, the wax model melts away inside the clay, leaving a hardened shell mold. This clay mold is then used to make the final sculpture.
4 Molten metal Molten (liquid) metal is poured into the clay mold and left to cool and harden. For this sculpture of an African head, a mixture of copper, zinc, and lead was used.
5 Metal sculpture When the metal has cooled, the clay shell is broken open to reveal the finished metal sculpture.