Friday, July 30, 2010

PMC workshop

Just wanted to tell y’all about the PMC workshop I went to on the 23rd. It was mostly basic info about PMC. Did you know PMC was created by Mitsubishi? (The metal works division, which is a sister company to the car maker.) Our instructor said it is believed the binder in PMC is cornstarch, so even the fumes from the kiln are not toxic. Really old PMC will sometimes grow mold because of this but is still usable until it dries out. After PMC has dried out, you pretty much can’t reconstitute it. You can add water to make it creamy and use it for slip (much like clay slip) to bind jump rings and pieces of PMC together. It was believed this material would sweep the jewelry industry but that hasn’t happened. Jewelers stick to their craft using torches, saws, grinders, etc. PMC really appeals more to crafters like me who don’t know metallurgy and are kinda afraid of all those traditional jewelers tools. The original PMC had much larger particles of metal, which means more air holes around them once the binder burns away. As a result, it is very brittle after firing. The newer stuff (PMC+ and PMC3) have much smaller particles of metal, so Nancy recommends them. She told about wearing an early PMC ring during a car accident where she was not hurt but the ring hit the dash and shattered. The precious metal clay with the lowest firing temp has the smallest particles – not sure if it was + or 3. During firing the edges of the metal get “sticky” but the metal doesn’t actually metal. The particles fuse together as the binder burns out.

We worked with very small amounts of clay (that was included in the price of the workshop) – we tried the silver, brass, and copper PMC. They have recently added steel PMC to the lineup, too. While the kiln was firing our pieces, Nancy showed us how to fuse copper and silver and do enameling with a torch. That was fun but the fused pieces I tried pretty much sucked. I burned out the middles of two of them with the torch. : )

fired bronze PMC pieces She showed us how to add jump rings to the backs of pendants using PMC and also how to set stones. There are a lot of stones that won’t work including diamonds. They turn back into carbon in the kiln. CZs will work, though. Rio Grande sells stones that will work with PMC. Lab grown stones work better than natural ones because the natural impurities can cause stones to break or burn out when firing. Some things, just as with glazes in traditional clay work, seem to happen by serendipity (or not) when firing PMC.

silver fused on copper - unsuccessfully
The best part of the class was learning about mold-making for PMC – you can use the two part stuff from Rio, or Hobby Lobby (I’m going to try the really flexible kind from hobby lobby like Tim Holtz recommended since I have some of this), cheap polymer clay, or 100% clear silicone caulk if you want to make a lot of molds. Did you know that E6000 and Goop are really just 100% clear silicone caulk? You can use those two products to make molds as well but the caulk is much cheaper. There was a lady in our class who brought in some really cool Chinese boxes. I made a couple of molds from them - bamboo and a dragon. (thanks Betsy!)

fired and tumbled silver PMC piece If you decide you love this medium, the start up cost is reasonable. Around $1300 will buy everything you need to get started from Rio. They have a kit that includes the kiln, a tumbler, and other pieces you need. The best part of PMC according to Nancy is that it really brought down the prices on kilns that have precise temperature controls. You can use the PMC ones for enameling, glass fusing, and small ceramic pieces as well. The tumbler helps polish your pieces and also work hardens the metal to make them stronger. You can burnish them to help strengthen and clean them but tumbling is faster and less labor intensive especially for really small pieces.

fired copper PMC piecesIt was a great workshop. Thanks Nancy!