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Bronze wax castings begin about 2000 BC in the Middle East with the discovery of beeswax molded in wet clay and burned in a fire leaving a cavity for hot metal. Alloys of tin and copper, probably natural that does occur in nature in small quantities were melted into the empty casting creating a metal object. Today the process is similar although modern materials are used to replicate the basic ingredients. |
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Sand casting of a symmetrical item today is the ideal sister of the old process. But the popular method utilizing new substances takes the wax into a modern cast of ceramic shell which is burned out with a high temperature torch, and which then accepts the molten metal. The ceramic shell reaches temperatures of 1000 degrees and the metal bronze melts at 2000 degrees in a small furnace developed for personal use at home by the artist. |
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The lost wax process incorporates many materials in a long process of losing the original design or maquette. Using direct wax or working from a clay sculpture, the artwork is divided and molded with a polyurathene or latex mold backed with a plaster cast for support. |
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The mold is removed and wax is poured or brushed into the latex mold. A study of the liquid movement is involved to decide on the plumbing required for the process. Plumbing called gating is attached in wax with a pour cup. It is essential that gasses and air can escape during burn and pour because the pressure of the hot metal is great. |
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Once gated, the wax is then coated with a binder and sand mixture several times. This is the ceramic shell.
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The shell is then burned out leaving a vacuum of space which was the design and plumbing within the shell. The shell still hot, is then positioned to accept the molten bronze metal. When cooled, the shell is broken off and the success or the errors are exposed. The plumbing is cut off, braising or welding takes place to complete, and then polish followed by a hot chemical painting of patina colour.
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The artist does all her own work in the process except welding, and her spouse developed and built the small portable furnaces. Carolyn and George do demonstration pours with their furnaces in the summer. The furnace is used until the weather is inclement, and then the sculpting and shelling is worked on until the weather improves again for the pours.
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