QNK Clay Graphite Crucibles
Our graphite crucibles are high quality melting crucibles. They can be used at temperatures up to 1800 °C (3300 °F) and are suitable for melting and refining precious metals, base metals, and other products.
It is helpful to preheat crucibles to drive of any moisture that may have been pulled out of the atmosphere during manufacturing, storage, shipping, and cooling from the previous firing. And for high value fires (like refining), it is good insurance.
Preheating can be done by placing the crucible on top of the furnace, or on a hot plate, or by putting them in the furnace and raising the temperature slowly.