There are  two manufacturers in metal clay; Art Clay and Precious Metal Clay

All silver metal clay is composed of fine silver particles, organic binders and water.  The clay can be molded, shaped and textured.  When the clay is completely dry it can be filed carved and sanded.  After finishing, the clay is fired with a gas stove top, butane torch or in a kiln at high heat.

During the drying and firing process the water evaporates, the binders' burn away and the resulting solid metal piece is strong and sintered.  Once fired the remaining piece is .99% pure silver. 

People often ask me what the difference is between fine silver and sterling silver.  As explained fine silver is .99% pure silver.  Sterling silver is .925% silver.  Sterling silver is an alloy of silver that consists of 92.5% pure silver and 7.5% of other metal, usually copper.

Metal clay is available in silver, gold, copper, bronze, gold bronze, white bronze and steel.