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What is 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 created by making a powder of pure silver, gold, bronze or copper metal and mixing the powder with water and an organic substance called "methyl cellulose" to create a clay-like dough.

Methyl cellulose may sound like a nasty chemical, but it's actually made from the cell walls of green plants. It's a substance used in food additives and is non-allergic, non-toxic and perfectly safe to work with.

Metal clay can be modeled and formed like traditional modeling clays, and when dried 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 a common method for making objects from powdered metals by heating the material below it's melting point until it's particles adhere to each other.

Each type of metal clay, gold, silver, silver alloy, bronze and copper have different sintering temperatures because each metal has a different melting point. Silver and gold are noble metals (they do not oxidize during firing) and offer the widest range of firing options. PMC Pro, a new silver alloy clay, and copper and bronze clays require special firing techniques because they contain copper, which oxidizes during firing. While copper clays can be fired with a torch for experimentation and some small projects, bronze and PMC Pro always require a kiln for firing.

For the beginner, fine silver clay is the easiest and quickest way to experience metal clay because it can be fired by hand held torch, in a tabletop jewelry kiln or even on a stove burner in as little as 2 minutes.

Copper based clays (PMC PRO, bronze and copper clays), on the other hand require the use of a programmable kiln. To successfully sinter, copper-based clays must be protected in a bed of carbon during firing and held at very specific temperatures.

If you already have a programmable kiln and want to work in silver alloy or in bronze or copper (less expensive forms of metal clay), you'll have an advantage and all metal clays will be open to you.

Fine Silver Clay
There are 2 major brands of fine silver clay: PMC and Art Clay Silver. We offer both brands of fine silver clay and all of the available formulations of each. Both brands of fine silver clay are made from powdered fine silver. Fine silver is pure silver, which is not the same as sterling silver. Sterling silver is an alloy, which means it's a mixture of metals. A sterling silver item will have a mark stamped on it that reads ".925", which means that the fine silver content of the article is 925 parts, with 75 parts being some other metal (traditionally copper). Fine silver is marked as ".999" which seems like it might not be pure because it's not 1000, but it's considered pure silver and is called "Fine Silver", just as pure 24K gold is called "Fine Gold".

Silver Alloy Clay
PMC Pro is a new silver clay that is an alloy of 90% fine silver and 10% other metals. (This clay will be available in October, 2010) The silver content of PMC Pro after firing is 90%. This clay offers the user a stronger final product, but it must be buried in activated carbon during firing to avoid oxidation of the clay and for proper sintering (the clay would turn black if it is fired in the open air). We'll have more information on this clay as it becomes available.

Gold Clay
PMC and Art Clay are also available in gold. The price of gold being what it is, working with gold clay is recommended for the experienced metal clay artist and probably not the best form to experiment with for the beginner. Gold clays are either pure 24K gold or are an 22K alloy of fine silver and gold. 22K means there is 22 parts pure gold and 2 parts some other metal.

Bronze Clay
Bronze clay is more challenging than fine silver clay because it can only be fired in a digitally controlled tabletop jewelry kiln (which costs about $500). If you already have a small kiln, your in luck! But, if you have a large ceramic kiln, it is probably not suitable for bronze clay firing. A small kiln is needed because the firing temperatures and hold times for bronze clay are critical to successful firing.

Copper Clay
Copper clay can be fired by torch, but requires quenching (dunking in water) and pickling (an acid bath) to remove the oxidation from the surface. Torch fired copper also does not sinter as fully as kiln fired copper, so it's not as strong. Torch firing copper clay is a good option if you want to play with a low-cost metal clay.