It has been a boon to the ceramics industry and is widely available. It comes in several grades and thicknesses. In this application it doesn't take much in the way of thickness to chink the cracks at the joints of the bricks. Return to link Crucibles Crucibles are pots made of metal resistant refractory material. That means they resist heat and can stand up to the outward pressure of molten metal inside.
Crucibles also transfer the heat from the flame to the metal inside.
The crucibles I'm familiar with are either made of clay or carbon. Carbon crucibles are the toughest and most common metal casting crucibles around. The carbon actually burns up but slowly and in doing so makes an excellent heat transfer material. Two types are available through foundry supply houses and some of the larger jewelry supply houses. They work just fine.