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.
These clays are mixtures of very small metal particles, 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 (and fired) state - can be drilled, carved and engraved. There are few limits on the uses of these clays. They are fired until sintered (heating the material, below the melting point, until the particles adhere to one another). The final state is pure silver or 24K gold - like the metals found in sheet form - only a bit more porous and as a result - not quite as strong. A well trained artisan will take the metal's weaknesses and strengths into consideration, when designing a piece, resulting in jewelry that will last forever (or damn close).
Silver metal clay comes in several varieties: Lump, Slip, Paper and Syringe. Each has it's great points as well as drawbacks. The idea is to try them all and see how they will best work for you.
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 (depending on the type of clay) generally between 1200 degrees F to 1650 F.
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.
How I Work with Metal Clay
For me, metal clay is the slow train. It takes me FOREVER to create a piece with metal clay. I know others rave about "instant" jewelry but it's not found here. On average it takes me about a week to create each piece.
Generally, I start by creating a shape to place my wet clay on. I use paper clay or cork clay - sometimes polymer clay and other times I use a mold made from a two part silicone putty. I have recently started making my forms in thin copper or brass sheet metal, oiling them and then applying the clay. The results are a bit crisper in detail than when using the paper or cork clays. The other benefit of using metal for forms is that I can leave the piece on the mold and put it in the toaster oven. You can do that with paper or cork clay but often times the clay sticks - even if well oiled. The cork and paper clay suck up the olive oil.
I make most of my own textures using photopolymer sheets and that two part silicone putty. I usually buy Belicold from Rio Grande but others work equally as well. See my more detailed description of photopolymer plates. The world is full of interesting textures - why use someone else's? Just in my office alone, I can find several hundred different textures. The next time I go on vacation, I'm bringing my Belicold (not in the carry-on, that wouldn't be pretty)
After texturing (or not), I create the components of the piece. If it's to be a box - I'll make a pattern in cardboard so that I can cut identically sized walls. Another piece might require the construction of a bunch of little flowers. elements are created separately and then joined with slip (a thinnish paste made from powdered metal clay and water) to the body of the piece. I dry my pieces on a coffee warmer or in the toaster oven. When creating flat pieces, I heat until partially dry and then flatten with these 2" X 2" ceramic bisque tiles (I get mine at a local ceramic supply house - I found a source on-line - which I haven't ordered from, called Cowtown Ceramics ) on which I plop a big old chunk of steel. I oil the steel because - it rusts!
Then comes the finishing! Egads, does that take a long time. Finishing usually entails carving something and I use (and love) Wolf Tool's wax carvers. PMC carves like a dream. The only problem with carving is my hands which tend to apply undue amounts of pressure to the weakest spot on the piece and Viola! it breaks. Now, I've got to add slip the broken piece, slip to the other part that it broke off from and then a small chunk of clay - kind of a "repair sandwich". That has to dry and then back to finishing.
Once I'm done carving and snapping off chunks I start sanding. I start with 320 grit wet/dry sandpaper (hardware stores) and move up to 400, 600, 1200, and more - if I want a very smooth surface. I use 3M's sanding papers called WetorDry Tri-M-Ite Polishing Paper. They are flexible and make sanding a bit easier. I sand for HOURS. Then I'll break something, AGAIN, and have to repair and re-sand. It's not my favorite part of creation. It's one of the reasons that it takes me so long to make pieces with metal clay.
Next Step is firing - which is a piece of cake since all that I have to do is to turn on the kiln.
After the kiln, and subsequent cooling, comes more finishing. Usually, the surface will need some more sanding (ugh) and buffing with a cotton buff and some rouge (red). If rouge is employed the piece needs to be scrubbed with hot water and a grease removing soap.
On to the Liver of Sulfur. Liver of Sulfur is a combination of various potassium sulfides and it smells like rotten eggs or that stench that comes out of the ground near geysers and bubbling mud pots. Everyone complains when the liver comes out. The fumes are dangerous. My work is dangerous. See the Patina section under materials for more information on Liver of Sulfur. Liver of Sulfur is used to darken or color metal. With silver you can achieve a rainbow of colors.
After the patina is applied, the piece is either left as is or, as usually happens with my work, the patina is removed from high areas with steel wool and pro-polish pads (available through Rio Grande).
Finally, the piece is put together with hand-made chain or beads or some other product - which is another process unto itself.
TIPS
When re-hydrating clay add a few drops of vinegar to the water to keep it from growing mold.
Miter Cutting Vises are great for creating square edges as well as great 90 degree bevels - even on PMC. You need to insure that at least one edge is square. See my discussion on the use of this tool in my Tools section.
Shopping for Clay
You can find PMC, Art Clay Silver at: Whole Lotta Whimsey, Cool Tools, Metal Clay Supply and Rio Grande, to name a few of my favorites.
Videos
PMC Videos/Art Clay Silver Videos:
