Precious Metal Clay (PMC) represents a dramatic development in the handling of precious metals. PMC consists of microscopic particles of silver or gold suspended in an organic binder to create a pliable material with a consistency similar to modelling clay. PMC can be worked with the fingers and simple inexpensive tools to create a vast range of forms and surfaces that would be unattainable or laborious with traditional techniques.

When heated to a high temperature, the binder burns away and the metal particles fuse to form solid metal that can be sanded, soldered, coloured and polished like conventional material.
History

Precious Metal Clay was developed by scientists working at the Mitsubishi Materials Special Products division in Sanda, Japan. After years of experimentation the first patents were awarded in the early 1990s with many additional materials joining the family of products. The principle ingredient of PMC is gold or silver, reduced to tiny flakes smaller than 20 microns in size. As a point of reference, it would take as many as 25 of these particles clumped together to equal a grain of salt.

The other ingredients in PMC are water and an organic (naturally occurring) binder. After firing, the water and binder have completely burned away so what remains can be hallmarked as .999 silver or gold. Dried out or unwanted objects can be recycled / refined just like conventional precious metal.

How Does It Work?
Under the proper conditions, crystals of metal fuse together in the same way that droplets of water run together to make larger puddles on the window pane. In the case of metals, oxides (tarnish) that form naturally on most metals prevent this from happening. The solution here is to use precious or noble metals in their pure state. These do not readily oxidize so even at the high temperatures needed to induce fusion they remain free of coatings. This explains why there is not a brass or sterling version of PMC - short of firing in a vacuum it won't work.