Art Clay Silver is water-based clay made of pure silver powder, water and non-toxic organic binder (bonding agent.) Once Art Clay Silver is dried, it becomes hard like plaster, enabling you to carve it, engrave it, file it and sand it to a perfect finish before firing. Even after drying, Art Clay Silver may be changed back to clay with the addition of water. Leftover pieces and powder resulting from filing may be recycled as clay, leaving no waste. After firing, Art Clay Silver becomes 99.9% pure silver which can be hallmarked.