PMC (Precious Metal Clay) and Art Clay Silver (ACS) are new materials on the art/craft scene. PMC and Art Clay Silver come in pure silver and 24K gold. NEW! PMC Pro, which has been released, was announced at the 2010 PMC Conference. PMC Pro is 90% Silver and 10% unknown (my guess is copper) – this makes the silver content less than sterling silver which is .925 silver. To correctly mark jewelry made with PMC Pro you will have to use a .900 mark. The Pro’s (hah) of PMC Pro is its strength. This chart shows a comparison of all the PMC clays, including Pro and sterling silver. One note on this new clay – IT IS EXPENSIVE! About $113.00 (retail) for 50 grams (approx. 1 3/4 of an ounce) and a lot of that weight is moisture and binder – not silver. As of 12/10, PMC+ is about $78.00 US for 45 grams ( about 1 3/5 of an ounce). Less silver, more money? Probably passing off the R&D costs to us consumers. Thanks. I’ll use sterling sheet instead – I can still get that for under $40.00 an ounce. As of 3/13/11 silver (in sheet and wire form) now runs me about 43.00 an ounce. Wish the market would stop going up – pretty soon I’ll be working with gravel!
The differences between these brands of clay is subjective as well as chemical. See Tim McCreight’s and Darnel Burks comparative testing of PMC 3 and Artclay 650 (notice the picture on the bottom right of the hand, carving a piece – that’s my hand and my piece!).
Metal clays are mixtures of very small metal particles with an organic binder and water. The clays are elastic and are similar in texture to modeling clay. They can be molded, coiled, stamped and – in an air dry state – can be drilled, carved and engraved. There are few limits on the uses of these clays.
Briefly, creating with metal clay is as follows: the object is formed using the moist clay, all the moisture is then removed by using either an electric heat source or allowed to air dry. Next, the object is fired in a kiln or exposed to another source of high heat, like a torch, at a range of temperatures generally between 1200 degrees F to 1650 F. These temperatures vary depending on the type of clay being used. Bronze, copper and steel clays have different firing requirements. See my page on Bronze and Copper Clays.
Firing causes the piece to shrink and the resulting shrinkage needs to be accounted for in the design. Shrinkage rates vary from 8% to 30% depending on the type of clay. Firing sinters* the metal, burns away the binder and leaves behind pure metal.
Shopping for Clay
Magazines and Publications
There’s a new kid in town (as of 2010): Metal Clay Artist Magazine. This is a beautiful magazine full of great new ideas and images.
Art Jewelry Magazine regularly features articles on Metal Clay. We love Art Jewelry!
* Sintering: a material is heated below its melting point until the particles adhere to one another.