Reading Selection, Lesson 7
The artist carves a model in wax (usually beeswax). Wax is soft, and the artist can use it to produce intricate carvings. After completing the model, he attaches tiny wax rods (called sprues) to it that will produce channels in the mold for draining the wax and receiving the gold.
In this technique, an artist produces a clay mold around an easily carved substance: wax. When the mold is heated, the wax, which has a melting point less than 70 °C, melts away. The hard clay mold can then be used to produce jewelry made from metals with high melting points. The artists often use gold, which has a melting point of more than 1000 °C.
|The artist covers the wax figure with several layers of fine wet clay. Coarse clay is then added in layers to complete the mold. The clay mold is placed in an oven and heated until it hardens. The wax melts and runs out of the mold (in other words, it’s lost!).|
|The wax model is carefully cleaned before the first layer of fine clay is added.|
|Air is pumped by hand bellows into a charcoal furnace. This produces the high temperature needed to melt gold.|
The pictures here show the major steps in lost wax casting. In these pictures the artist is using gold.
|Pieces of gold are placed in a crucible.|
|The crucible is attached to the mold. The two parts are then sealed together using more clay.|
|The mold and gold are heated together in a furnace. When the gold has melted, the mold is turned over so that the metal flows into it. The mold cools. The clay mold is cracked off, leaving a casting.|
|The artist files away a few rough edges, and the jewelry is ready.|
|The lost wax method has been used to produce a variety of objects, including this figure of a king from Nigeria.|
|Recently, new uses have been found for lost wax casting. It is one technique used to produce precision parts, such as these—designed for aircraft and other machines.|