Metal clay

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Metal clay, is a clay-like medium used to make jewelry, beads and small sculpture, consists of very small particles of precious metals (such as silver, gold or platinum) mixed with an organic binder and water. Once the clay is worked, then dried, it is fired in a kiln or with a hand-held torch. The binder burns away, leaving just metal. The resulting object is smaller because the binder has been removed.

Silver clay is the most-used of all metal clays, resulting in .999 pure silver. Gold clay is quite expensive, and not practical to use by itself, but the gold makes a beautiful accent on the silver. The clay comes in packets, which are small because the material is very expensive: $30 an ounce is standard for silver clay.

There are two popular brands of this material, Art Clay Silver (ACS) and Precious Metal Clay (PMC).

Precious Metal Clay or PMC is a plasticene-like precious metal compound developed in the early 1990s in Japan by metallurgist Dr. A. Morikawa. The material consists of extremely fine precious metal powder in a colloidal suspension, which burns off on firing. Success was first achieved with gold, and later duplicated with silver. The material is modelled into the desired shape, and then kiln-fired; which burns off the carrier, leaving only the pure metal. Shrinkage from 8 to 20% occurs (depending on the variety used), but this has been exploited by artisans as it allows very fine detail to be achieved.

Mitsubishi Materials Corporation, a subsidiary of Mitsubishi, has developed two additional versions of silver called PMC+ and PMC3, which display less shrinkage, and fire at lower temperatures in a kiln or by using a blowtorch. A 22k gold coating material (Aura 22), and a 22k yellow gold alloy are also manufactured.^[1]

PMC was originally imported into North America by only one company, Rio Grande, which sponsored a number of workshops and symmposia, and started the PMC Guild^[2], which have lead to relatively fast acceptance of the material into the western market. Another brand, Art Clay Silver (ACS), made by Aida Corporation is marketed in Europe and the United States