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METAL
Like stone, metal makes for a perfectly serviceable pattern material, provided the weights involved are not excessive. Lightweight metal patterns constructed in aluminium and other light ‘white’ metals are common in commercial sand foundries, especially if the dimensional accuracy of he pattern has to be maintained over a long production run. Metal patterns are also common in jewellery casting, this is because the master pattern is often (rubber) moulded under conditions of heat and pressure, and must therefore be robust enough to resist distortion (see REPRODUCTION MOULDING).
Light metals such as a aluminium, magnesium, tin, and white metals are well suited to patternmaking because they are all weight efficient and easily handled in the foundry. Often as not, the metal patterns seen in art foundries are original welded steel constructions for translation into a cast edition (many of Picasso’s and Gonzalez’s fabricated steel sculptures for example have been reproduced in this way). The founder may also be asked to produce an edition from a sculpture that was previously produced as a unique lost pattern cast.
If a welded construction is going to be used as a foundry pattern, remember that details such as welding spatter and hammer marks are likely to be seen on the cast unless first machiened from the pattern. If the original metal design has a delicate patina or other fragile finish, the founder will need to take similar precautions to those outlined in for STONE if incidental surface damage or staining on the pattern is to be minimised.
RESIN & PLASTICS >
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Metal patterns are extremely robust and long lasting, this aluminium example has been specifically made to enable a repeat series of bronze sand casts without deterioration of the master pattern.
Most metal patterns sent to lost wax foundries are either ‘one off’ cast lost pattern sculptures or else fabrications formed in materials like steel. (Photo R. Moule/Sculpture Factory London). |
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