Speculum metal metal mixtures usually contain two parts copper to one part tin along with a small amount of arsenic, although there are other mixtures containing silver, lead, or zinc. The knowledge of making very hard white high luster metal out of bronze-type high-tin alloys may date back more than 2000 years in China although it could also be an invention of western civilizations. Such metals were used in sculpture and to make more effective mirrors than the more common yellow easily tarnishing bronze mirrors. In that era mirrors of speculum metal, or any precious metal, were rare and only owned by
Metal clay added to hydrate and kneaded to attain a clay consistency. One advantage to the powders are their unlimited shelf life. The first silver clay in powder form was released in 2006 as Silver Smiths' Metal Clay Powder. In the following years base metal clays by Hadar Jacobson and Goldie World released several variation containing copper, brass, and even steel. Metal clay Metal clay is a crafting medium consisting of very small particles of metal such as silver, gold, bronze, or copper mixed with an organic binder and water for use in making jewelry, beads and small sculptures. Originating in Japan