A high-quality crucible, the best choice for melting larger and purer amounts of gold, silver, copper, and bronze. Made of fused silica with clay bond, for temperatures up to 2500°F (1371°C). Must be pre-glazed before smelting (instructions included). This size crucible fits inside the smaller GPK JR 7.5″ kiln and can be used inside the regular 9.5″ kiln – best to remove one of the 2″ kiln layers. Smelting time is much shorter than with the larger fused silica crucible; only around 30 minutes. Dimensions: 3.5″ wide x 3.5″ high.