About Metal Clay
Metal clay is a jewelry making material that
can be used by just about anyone to create
jewelry and small decorative objects. Metal
clay is made from powdered metal mixed with
water and a substance called "methyl
cellulose". Methyl cellulose may sound like a nasty chemical,
but it's actually made from the cell walls
of green plants. It's an organic ingredient used in
food additives and is non-allergic, non-toxic
and perfectly safe to work with.
Metal clay handles similar to traditional modeling
clays, and, when dried, it is transformed into a solid
object through a firing process. During firing, the methyl
cellulose, typically called "binder",
is burned away and the metal particles "sinter"
into a solid form. Sintering is the process of making a powdered material (in this case, metal clay) coalesce into a solid mass by heating it to a very high temperature, just below the point of liquefaction.
There are several types of metal clay available:
fine silver, silver alloy, gold, gold alloy, copper, bronze and steel. Each type of metal clay has unique
firing requirements because each metal has
a different melting point.
For the beginner, fine silver clay is the
easiest and quickest way to experience metal
clay because there are so many options for firing, including low cost hand held butane torches. All metal clays are optimally fired in a jewelry kiln and some require special firing methods. The overview below will give you the basics on the different types of metal clay and their firing requirements to help you decide which clay to begin your adventures with.
Types of Metal Clay & Firing Requirements
Fine Silver Clay
Cool Tools carries almost every brand of fine silver clay that is available. FS999, PMC and Art Clay Silver. All of these fine silver clays are made from powdered fine silver that is .999 in purity and considered pure silver or "fine" silver.
Fine silver clay is the easiest and fastest of all metal clays to fire. In as little as 2 minutes you can transform dry clay into a pure fine silver object.
Minimum Firing Time: 2 minutes
Firing Options: Torch, gas burner, enameling kiln, jewelry kiln
Silver Alloy Clay
EZ960® Sterling, PMC One Fire Sterling and PMC Sterling are silver metal clays that are made of fine silver, copper and other metals. This type of mixture is called an "alloy" and results in a metal that is far stronger than pure fine silver. Metals are alloyed to enhance or impart characteristics that are lacking in the main metal. Fine silver is a metal that is easily dented and scratched. By adding other metals, an alloy with greater strength is created. Sterling Silver allows jewelry artists the ability to make thinner, more delicate jewelry that meets any jewelers standard for durability.
Minimum Firing Time: 1 hour
Firing Options: Carbon Firing (kiln required)
PMC and Art Clay both offer gold clay products. Gold clays are either pure 24K gold or 22K alloy of fine silver and gold. 22K means there is 22 parts pure gold and 2 parts some other metal. Can be fired with a hand held torch in as little as 2 minutes.
Minimum Firing Time: 2 minutes
Firing Options:Torch, gas burner, enameling kiln, jewelry kiln
Bronze is an alloy of copper and tin. Bronze is a very hard metal and is the strongest of all the metal clays available. We offer many types of Bronze Clay. BRONZclay and FASTfire BRONZclay by Metal Adventures, Inc, Hadar Jacobson, Goldie and our own brand, Aureus Bright Bronze Clay. The difference between BRONZclay and FASTfire BRONZclay is the firing time required, the shrinkage, and the color of the finished metal. Hadar Jacobson and Goldie Clay are powdered clays. Powdered clays are distinctive in that the artist adds water to create the amount of clay wanted or necessary, with the powdered remainder having an extended shelf life.
BRONZclay is fired according to the thickness of the finished piece. The thicker the clay, the slower the firing. The thinner the piece, the faster the firing. This version shrinks about 25% during firing and is a warm bronze color.
Minimum Firing Time: 3 hours, 4 hours is average
Carbon Firing (kiln required)
FASTfire BRONZclay usually fires at full speed, but in some larger kiln models, the heating is slowed to 1000°F/hour. This version shrinks about 20% during firing and is a golden bronze color.
Minimum Firing Time:
2 hours, 3 for extra strength
Carbon Firing (kiln required)
Copper clay is made of pure copper. We offer many excellent brands of copper clay, Cyprus
™ Copper Clay, COPPRclay by Metal Adventures, Inc and Art Clay Copper. COPPRclay and Cyprus must be fired in a kiln in activated carbon. Kiln
firing takes about 3 hours.
Minimum Firing Time: 5 minutes
Torch or Carbon Firing (kiln required)
Shop Cyprus Copper Clay
Managing Metal Clay in its Wet Stage
Metal clay is best when it is fresh, directly out of the package. But what happens after the package has been opened and the artist has worked with it? This article discusses various methods to help manage metal clay and to keep it working at its best in its wet stage.
A very smart metal clay artist once told me: “Leave the metal clay in its package and don’t even open the package until you are positive in your design. At a minimum, work out your designs on paper first, or, better yet, use polymer clay or something similar to work out your design issues/challenges before you go creating in metal clay. You can learn a lot about your design and gain confidence in your creation by working out the details in a similar clay medium rather than jumping in and going straight to metal clay.”
Notorious for drying quickly and losing its hydration, metal clay moisture is lost primarily by evaporation through exposure to air and also by working the clay with dry hands which will pull moisture from the clay. When clay loses too much moisture, it cracks and can break during use, making the creative experience frustrating. Conversely, too much moisture can cause the lump clay to become too sticky or too wet to work with. The metal clay industry calls this over hydrated phenomenon slip or paste, and there is a use and a need for these products, but when lump clay is needed, too much moisture is problematic as well.
Generally speaking, metal clay consists of tiny metal particles, distilled water (no impurities in distilled water), and binder. The addition of binder is what makes the metal particles adhere to themselves to create the clay-like product. But what happens when too many additives are introduced into the clay? The binders break down, making the clay difficult or even impossible to use.
Handling the clay too much by rolling, texturing, re-rolling, and re-texturing the metal clay repeatedly can break down binders and render the product difficult to use. Placing overworked clay in a hydrator and letting it rest overnight will help the clay perform better.
Resist the impulse to add anything foreign to the clay. Again, metal clay is at its best right out of the package and when it is not contaminated with any other product. The overuse of anti-stick products (also known as lubricants, releases or oils) will have a cumulative and detrimental effect on the workability of the clay. Because metal clay artists use these products regularly as metal clay can be “sticky”, they should minimize the amounts used as they interact negatively with the binders in the clay. This can cause the clay to crumble, crack, and lose its ability to hold together well. When rehydrating the clay, the only thing that should be added is distilled water.
Overworked or dry clay can often be restored by conditioning. This is a process in which distilled water is added and worked into the clay to restore hydration. There are many ways to achieve this, and it seems every artist has their own process or technique. One method is to place the overworked clay in between two layers of Saran™ or plastic wrap. The artist then rolls the clay into a thin slab and adds a light mist of water (always add distilled water, as it has no impurities) to the surface of the clay. Then, the clay is folded over onto itself, entrapping the moisture within the clay. The clay can then again be rolled thin, and a tiny amount (fine mist) of distilled water is added again, and the clay is folded yet again. This process is repeated several times to add and evenly distribute moisture throughout the clay, from the center recesses all the way through to the outside. It is helpful to remember that metal clay dries out quickly, but rehydrating clay is a slower process. It takes more time for the binders to accept moisture than it does for the binders to release moisture. If time allows, and for best results, condition and rehydrate clay and then let it “rest” overnight in a metal clay hydrator. A hydrator is a simple tool that consists of a jar or container that includes a sponge hydrated with distilled water. The sponge offers a humid environment for the clay to rest in. Hydrators are also a good place to keep clay for long term storage.
Salvaging Overworked Clay
Clay that has been overworked or contaminated with additives can sometimes be salvaged by incorporating small portions of it into fresh clay. Add 20% of the overworked clay into 80% new clay. Be sure to mix these two clays thoroughly for best results.
Restoring Dried Clay
Sometimes clay can get so dry and hard that normal rehydration techniques won’t bring it back to a useable condition. When this happens, the clay can be restored by grinding it back to a fine powder with a coffee grinder or similar tool. By adding and mixing distilled water slowly, dried clay powder can be restored to a workable clay.
To get the best from metal clay:
- Be confident in your design.
- Work in a cool, humid environment.
- Handle and work the clay minimally.
- Resist the impulse to add anything foreign to the clay.
- Keep the use of anti-stick products to an absolute minimum.
- Condition with distilled water only.
By using these methods, artists will increase the performance of the clay and minimize waste. Additionally, and perhaps more importantly, the frustration of working with poor performing clay can be replaced with the joy of creativity.