Lost wax process
 Bronze Casting (direct method), Smarthistory at Khan Academy, accessed January 6, 2013 |
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Adriaen de Vries's Bronze Casting Techniques, J. Paul Getty Museum, accessed January 22, 2013 |
Lost-wax casting (also called "investment casting", "precision casting", or cire perdue in French) is the process by which a duplicate metal sculpture (often silver, gold, brass or bronze) is cast from an original sculpture. Dependent on the sculptor's skills, intricate works can be achieved by this method. The oldest known examples of this technique are the objects discovered in the Cave of the Treasure (Nahal Mishmar) hoard in southern Israel, and which belong to the Chalcolithic period (4500–3500 BC). Conservative estimates of age from carbon-14 dating date the items to c. 3700 BC, making them more than 5700 years old. Though the process today varies from foundry to foundry, the steps used in casting small bronze sculptures are fairly standardized. (In modern industrial use, the process is called investment casting.) Variations of the process include: "lost mould", which recognizes that materials other than wax can be used (such as: tallow, resin, tar, and textile); and "waste wax process" (or "waste mould casting"), because the mould is destroyed to remove the cast item. Lost-wax casting was widespread in Europe until the 18th century, when a piece-moulding process came to predominate.
Casts can be made of the wax model itself, the direct method, or of a wax copy of a model that need not be of wax, the indirect method. These are the steps for the indirect process:
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