Learning a new technique: PMC

For years I’ve been curious about the magical material known as precious metal clay (PMC). Until recently I believed it was only the purview of people with fancy kilns and more than adequate ventilation but I was wrong!

In the simplest of terms PMC is a clay-like substance consisting of silver particles, an organic binder and water. This means that you can sculpt, shape and mould it, let it dry then fire it just like clay. The fundamental difference being that when you fire it (in a kiln or with a torch) the organic binder is burned away and you’re left with just silver! Pure wizardry! Of course there is a small amount of shrinkage (around 10-15%) which is delightful to watch, much like Shrinky Dinks.

The original sculpt for the Clandestine Library Necklace

Sculpting

Apart from the general novelty of working with such a fascinating material and the obvious benefit of achieving dimensionality, what I really wanted was to learn a new technique which enabled me to produce equally detailed work in less time (this may come as a surprise to many but saw piercing can be time consuming and strenuous 😉 ). This led me to the process of making a mould which I could use to make multiple items, saving me a little time and my shoulder muscles.
To make the mould I first sculpted a little bookcase out of a polymer clay (yes I did make my design ridiculously tiny and detailed. Yes I did have to sculpt it with a pin. And yes, there is a cat in it. It’s in my nature). Then I created a well and covered the clay in resin in order to get a hard mould.
I won’t pretend that pressing the PMC into all the nooks and crannies of the mould while it’s coated in oil then trying to get it out again before it dries isn’t a little tricky. That bit is a work in progress.

Firing

So this is the part which held me back for years! I was under the impression that you needed a kiln to fire the PMC when in fact if you’re just using the fine silver version you can get away with a simple torch. Revelation! The best bit is that with a torch (after drying out the piece so there’s no water left) it only takes about 3 minutes to transform a piece of clay into a silver jewel. It’s like alchemy but better.
After firing (and trying very hard not to melt it) you simply clean it up and finish it however you usually would a cast piece (I like to oxidise it then use a brass brush on the highest surfaces to increase the contrast and sense of dimension).

You can achieve a surprising amount of detail and it really is quite fun. However, if you’re a novice with the torch I would recommend testing out your firing technique on a small piece first as PMC is considerably more expensive than regular silver sheet or granules.

So far I’ve just tested out a couple of designs (see below) but my poor brain is overwhelmed with the possibilities. Don’t worry, I haven’t abandoned my beloved sawframe, hopefully I can use both techniques in tandem to create something truly exciting. Stay tuned!