Saturday, May 31, 2014

Using Moulds in Precious Metal Clay

Precious metal clay (or PMC) is one of the most versatile and malleable forms of producing detailed and intricate jewellery without having to spend hours chasing and engraving. PMC, sometimes also referred to as silver clay, works on the same principle as many art clay substances. Tiny particles of precious metal (either silver or gold) are suspended within a binding agent, forming a clay-like substance that has the same moulding properties as art clay. However, rather than being simply dried PMC is fired, burning off the binding agent and leaving the precious metal behind.

Because of these properties, PMC works exceptionally well with moulds of all kinds. For beginners, even a bar of soap can be used as an effective mould, impressing a design into the surface of the clay that can then produce precious metal jewellery incorporating intricate designs with very little effort.

How to use PMC with moulds
Silver clay lends itself to both home-made and commercially produced moulds. Using a mould also allows for repeated elements and the production of multiple pieces all incorporating the same design. Hollow moulds also allow you to produce lightweight work and to make your precious metal clay go further.

A simple way to start is to use a bar of soap to form the basis of a mould. Simply carve a pattern into the surface of the soap and then press the precious metal clay into the depression, ensuring that it is forced into every corner and recess of the carving. Then just peel away the PMC and you have a pattern embossed into the surface of the clay. This can then be worked to tidy up any uneven lines or areas that may have not come out as crisply as you would like. Once you are happy with the design, the piece can then be fired to burn off the binding agent and the metal polished and finished to produce a beautiful piece of gold or silver jewellery.

Using moulds sold in hobby shops or from specialist retailers online is also an excellent way to produce fine quality precious metal jewellery on a budget. Any mould designed to produce candles, plaster or even candy will work, and even butter or biscuit moulds sold in cookery shops can be utilised to produce unusual jewellery of exceptional quality.

Making your own silicone moulds

However, it is possible to make your own moulds using two-part silicone compounds. These have the advantage in that they do not need to be lubricated. But if you do find that the precious metal clay sticks to the sides of the mould, a light coating of non-stick cooking spray will ensure that the clay can be removed easily from the mould without damaging the imprint on the surface.

When using PMC, you will have to take into account shrinkage. Early forms of silver clay suffered from quite dramatic amounts of shrinkage when fired, but modern versions have a far lower shrinkage rate. However, if you are using moulds that have a lot of fine lines, be aware that some of the detail may be lost in the final piece.

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