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Old 06-12-2007, 12:08 AM
jwebb jwebb is offline
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Join Date: May 2003
Location: Astoria, Oregon
Posts: 341
Re: What is the composition of CERAMIC SHELL

The exact composition of "Ceramic Shell" is considered proprietary, a closely guarded "trade secret", by the best foundries. That said, there are commercially available compositions. Search the web. The mixture or "slurry" is stirred into water in large pots, and the wax assembly dipped into it, then under a "rain" of sand, then dried; then dipped again, with as many as 15 or 20 dips being used to build up a "shell". That takes a sophisticated installation of equipment, or strong arms and backs, or both. When I was in Art school back in the 1970's, we used a mix of 2 parts Silica Sand, 2 parts Silica Flour, 1 part plaster, and 1 part Pearlite; put that in a 55 gallon drum, capped it, and rolled it around on the floor to mix. This dry mix was then added to water in plastic pans, much as plaster is mixed, and poured over the upside-down wax and gating and pour-cup assembly, which was standing inside a cylindrical mold. Results varied from great to very poor surface recreation. What I'd like to know is How did the Greeks and their contemporaries to it???
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