Types of Silver Clay explained – Precious Metal Clay and Art Clay

Metal clay is a suspension of tiny particles of metal in a clay binder, which can be used to make jewellery, beads and small findings. The beauty of metal clay is that it can be manipulated in the same way as any modelling clay, but once fired the binding agents are burnt off leaving the metal form intact. Although there is a certain amount of shrinkage (between 10-15% for the more modern versions), very fine detail can be achieved, including impressions that would require casting in any other method of metalwork.

Silver metal clay results in objects containing almost pure silver (also known as fine silver) which is ideal for enamelling. There are two popular brands available – Precious Metal Clay (also known as PMC) and Art Clay Silver (ACS). Precious Metal Clay was developed in the early 1990’s in Japan and consists of microscopic particles of pure silver (or fine gold powder) and a water-soluble binder which burns off during firing. The original formula of PMC (now called ‘Standard’) has to be fired in a kiln at a temperature of 1650F and has a high shrinkage rate of around 30%. Two additional versions were later developed called PMC+, which can be fired at 1490F and PMC3, which can be fired at temperatures as low as 1100F. Both of these later versions of PMC have much lower shrinkage rates, allowing much finer detail to be worked into designs.

Art Clay Silver (ACS) was also developed in Japan and is similar in consistency to PMC+. The main difference with ACS is that it can be fired using a hand-held torch or gas oven. Because of subtle differences in the binder components and the longer firing times, ACS benefited from having a considerably lower shrinkage percentage – only 8-10%. This means that ACS can be worked in more detail without any loss of definition in fine work. Art Clay Slow Dry was introduced soon after, which has a much longer working time before requiring firing, allowing intricate work to be moulded into the clay with no loss of malleability.

Art Clay 650 and Art Clay 650 Slow Dry are now becoming increasingly popular, as not only do they have a longer working time but can be fired at temperatures as low as 650C/1200F. This allows jewellers to incorporate glass and Sterling Silver into the designs without fear of damaging the components. AIDA, the manufacturers of ACS have also introduced Oil Paste, a product only used on fired metal clay or milled fine silver, and Overlay Paste which is designed for drawing designs onto glass and porcelain. These two products have allowed the use of metal clay products to be incorporated into a whole new range of designs and mediums, expanding the potential of this product.

Metal clays allow jewellers to work with a material that is as malleable as ordinary modelling clay but produces fine (almost pure) silver jewellery of exquisite intricacy and beauty. Once polished it has a lustre and shine that is easily comparable to cast silver and because of the development of the products over the last few years shrinkage is now no longer an issue. The type used depends on personal preference as both types have their advantages, but incorporating metal clays into your jewellery design gives you a new medium to explore with beautiful results.

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About the Author

Adam Hunter – E-commerce Marketing Manager of cooksongold.com. Cookson Precious Metals offer a choice of jewellery making supplies from over 10,000 products including gold and silver findings, tools, silver art clay and gold and silver sheet - gold, silver, platinum and palladium plus technical information for jewellers, jobbers, designer, craftsmen, artisans and students. Contacts Adam Hunter E-commerce Marketing Manager Tel(DDI): +44 (0) 121 212 6491 E-mail: adam.hunter@cooksongold.com