PMC Standard, PMC+ and PMC3 are exciting materials developed by Mitsubishi Materials Company. Composed of fine silver particles, organic binder and water, these products have the working characteristics of clay. The user can shape them in his or her hands using simple hand tools. After shaping and drying the pieces, they are fired in a kiln. The heat of the firing burns off the binder and causes the silver powder to fuse, leaving solid silver. The firing process is such that there is little or no change in the shape of the objects, only a reduction in size. PMC is also available in a 24 Carat Gold clay and a 22 Carat Gold paste.
Precious Metal Clays provide the artist user with a new way to create objects of pure silver and gold. These materials take advantage of the easy working characteristics of clay. They allow the artist to form shapes that would be difficult and time consuming to make using traditional silversmith techniques. Composed primarily of precious metal particles (either fine silver or gold), these materials receive their plasticity from the organic binder and water that hold the metal particles together.
The proportions of metal, binder and water differ between among the different types of PMC, with a greater percentage of metal in the PMC+ and PMC3 than in the Standard clay. These factors affect the rate of shrinkage and firing time, Standard PMC shrinks about 30% and takes 2 hours to fire. PMC+ shrinks about 12% and fires in as little as 10 minutes, PMC3 also shrinks 12%, but is made up of smaller particles and fires at temperatures as low as 1110F. PMC3 is the strongest of the silver clays. Each successive generation of the clay costs about 10% more than the previous version. Fired PMC work can be polished, soldered, enameled, and enjoyed like any other silver item.
All three generations of PMC are still available. Original PMC comes only in clay form. PMC+ comes in clay, paste, syringe and sheet forms. PMC3 comes in clay, paste, and syringe forms. All of these forms can be shaped using one's fingers or simple clay working tools. A wide range of artistic expression now is available to anyone interested. Join the many people who have discovered the magic of Precious Metal Clay.
Store PMC in a cool, dry location. Store all unused portions in the original foil package with a few drops of water; be sure to completely seal the package after squeezing out the air. If the clay begins to dry as you work with it, use a moist paintbrush to apply water to the surface of the clay. Allow the water to sink into the clay before proceeding (a few seconds is all it takes).Tools for working with the clay are straightforward and uncomplicated. We use potter's clay shapers, cutters and texture tools, plus leather working tools, craft knives and other assorted objects normally found around the home or shop.
When assembling PMC Standard we use a paste, made from a small amount of clay mixed with water, to secure the joints. For best results when working with PMC+ or PMC3 use the paste clay made specifically for that product type.Dry your work well before firing. The clay will air dry if left out overnight. You can speed up the process using a hair dryer, an electric griddle or a toaster oven set at about 150 to 200F (80 to 92°C). You can use the hair dryer either hand-held or as part of a drying box. Use the firing schedule for the most sensitive material being used, e.g. when firing a piece that contains glass use the temperature and time settings for glass, which is more sensitive than the silver. Be sure to refer to the specific firing instructions.
PMC is well suited for carving in the leather hard or bone-dry state. You can shape it with carving tools, chisels, files, scrapers, Dremel and other similar tools. Finishing should be completed as much as possible in the 'bone-dry' or unfired clay state. It is much easier to file or sand clay than solid metal. When it is bone dry you can sand and smooth it easily using emery boards or sandpaper. You can even use an alcohol tree wet wipe to smooth the surfaces. Spending time to finish your piece in this state will improve your results tremendously.
Fired silver will have a white surface. This is the way all fine silver looks after firing because the surface is rough. Light is not reflected well from this bumpy surface, resulting in a dull appearance. You will need to smooth it with a stainless steel wire brush. This will give the silver a matt finish. You can obtain a high shine finish by using a burnishing tool or a rotary tumbler. PMC is fine (pure) silver, with no other metals included. It is softer than alloyed silvers such as sterling. Sterling is a combination of silver (92.5%) and copper (7.5%). The addition of copper makes sterling stronger than fine silver. Therefore, chain links, bails or clasps made from fine silver should be thicker than those made from sterling. Reinforce any thin areas of PMC that may be subject to stress. This is to avoid breakage due to metal fatigue. The addition of copper in sterling also makes the metal more reactive to heat and chemicals. Sterling will react during firing to form a 'fire-scale' that is a blackening of the metal surface caused by the oxidation of the copper content. This scale can be removed using jeweler's pickle solution. This firing process also can result in a weakening of the sterling, making the metal more brittle and subject to breakage. If you insert and fire sterling silver, use wire 16 gauge or larger to maintain strength. Also it is better to use PMC3, with its lower firing temperature, if you plan to incorporate Sterling silver components.