Precious Metal Clay
Created | Updated Dec 2, 2004
Precious metal clay or PMC for short is a recent development for those who want to create silver or gold jewellery or art works. These metal clay products are manufactured by the Mitsubishi Materials Corporation and are available as 99.9% silver and 24K gold. In the early 1990’s the Mitsubishi Materials Corporation was looking for an innovative way to use their mined and recycled precious metals in jewellery making. The result was PMC, which the company has several patents for.
PMC is composed of metal particles, a non-toxic organic binder and water. The metal particles are measured in microns. The PMC comes in three forms; a clay which has the lowest binder and water content, a syringe of more fluid clay which has more binder and water than a clay lump and paste which has the most binder and water content. In each type there is just enough binder and water to hold the metal together in a workable form.
The artist or silversmith shapes the PMC like modelling clay into the desired shape. Since this is almost pure silver or gold the amounts are small one to five grams. Then sets it aside until dry. With a hair dryer about 10 minutes, or in a warm dry place a few hours.
PMC standard must be fired in a kiln to sinter or fuse the metal powder, a process, which drives off any remaining water and burns of the organic binder. This sintering requires a temperature of 1650° F (800°C) for a period of 2 hours. The result is solid metal with the characteristics of a cast of precious metal.
Once the metal piece has been fired, it is then possible to add precious or semi-precious stones, or to enamelling powder and re-fire the piece to create the final silver or gold object.
If the artist or silversmith is creating a ring for a finger, the shrinkage of PMC must be taken into account. This shrinkage is about 30% for Standard PMC and 12% for PMC+. As a finger ring has to be a good fit, the shrinkage has to accounted for bu the use of a size chart or by making the ring a few sizes bigger, before firing.
The clay is also produced in thin sheets which can be treated like a fabric before drying. These sheets can be folded, twisted, cut into strips, pierced and all sorts of manipulations, which can give it the texture and versitility for fine workmanship without having to cut and weld sheets of solid silver.
PMC is composed of metal particles, a non-toxic organic binder and water. The metal particles are measured in microns. The PMC comes in three forms; a clay which has the lowest binder and water content, a syringe of more fluid clay which has more binder and water than a clay lump and paste which has the most binder and water content. In each type there is just enough binder and water to hold the metal together in a workable form.
The artist or silversmith shapes the PMC like modelling clay into the desired shape. Since this is almost pure silver or gold the amounts are small one to five grams. Then sets it aside until dry. With a hair dryer about 10 minutes, or in a warm dry place a few hours.
PMC standard must be fired in a kiln to sinter or fuse the metal powder, a process, which drives off any remaining water and burns of the organic binder. This sintering requires a temperature of 1650° F (800°C) for a period of 2 hours. The result is solid metal with the characteristics of a cast of precious metal.
Once the metal piece has been fired, it is then possible to add precious or semi-precious stones, or to enamelling powder and re-fire the piece to create the final silver or gold object.
If the artist or silversmith is creating a ring for a finger, the shrinkage of PMC must be taken into account. This shrinkage is about 30% for Standard PMC and 12% for PMC+. As a finger ring has to be a good fit, the shrinkage has to accounted for bu the use of a size chart or by making the ring a few sizes bigger, before firing.
The clay is also produced in thin sheets which can be treated like a fabric before drying. These sheets can be folded, twisted, cut into strips, pierced and all sorts of manipulations, which can give it the texture and versitility for fine workmanship without having to cut and weld sheets of solid silver.
