So-called "lost wax" is a method of metal casting. It is now rare, but it was important in copper and bronze casting from antiquity up through small handcraft workshops in modern times. The French name, cire perdue is sometimes used in English for this technique.
The procedure is to sculpt the intended form of an artifact in wax and cover it with clay. The clay is allowed to dry and is baked in a ceramic kiln, which both hardens the clay and melts the wax, leaving an empty space where the wax was, into which liquid metal can be poured. The ceramic shell thus becomes the temporary mold in which the metal object will be cast.
Metal is poured into the clay mold, and when the metal has solidified, the clay is broken away, leaving the metal object in the form originally sculpted in wax. (By sculpting the wax over a clay core, the metal object can be left hollow.)
Because the clay mold is destroyed in the lost wax process, the method is not appropriate for mass production (say, of weapons), but it allows the creation of very fine individual art objects.
Needless to say, the quality of the wax and of the clay both matter. The ideal wax is hard enough to be carved and to retain its shape until it is deliberately melted. And the ideal clay is fine-grained enough to carry the impression of even the most minute details of the wax sculpture without adding undue coarseness of its own. As with any fired ceramics, the clay must be carefully handled to avoid premature cracking.
Because appropriate ores and clays were not usually found together, mining and casting rarely occurred at the same place. Mines leave slag, but the casting workshops leave little archaeological trace because the discarded molds were pulverized in the hope of retrieving any reusable crumbs of metal.
It is not entirely clear where the technique originated. It is known from ancient India and Pakistan. In China, it does not seem to correspond with the golden age of elaborate bronze production in the Shāng and Zhōu dynasties, which depended upon complex multi-piece molds, but rather to have arrived, possibly from India and possibly with Buddhism, sometime in the 400s or 500s AD.
Content Revised: 2013-06-05
Software Last Modified: 2025-02-04
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