Casting crucibles: types, uses and care

The crucible is the vessel in which metal is melted before being poured into the mold. It has to withstand very high temperatures and not react with the metal.

Types of crucible #

• Ceramic or fused quartz: for melting gold and silver with a torch; discarded when they crack.
• Graphite and silicon carbide: withstand heat and thermal shock; the usual choice for furnaces and larger quantities.
• Boron nitride (coating): reduces metal sticking to the walls.
• Clay-graphite: for large castings of bronze and base metals.

How to choose #

Choose the capacity according to the weight of metal you will melt (with a margin) and use a separate crucible for each type of metal to avoid contaminating alloys. The size must allow the flame or furnace to heat all the metal.

Use #

1. Preheat the crucible slowly, because moisture causes cracks.
2. Add the metal and the flux (such as borax, which helps remove oxides).
3. Melt with a torch or in the furnace until the metal is liquid.
4. Hold it with the crucible tongs to pour.

Care #

Store them dry and check them before each use: a crack can break under heat. Graphite crucibles oxidize with use at high temperatures, so they wear out over time.

See also #

• Jewelry oven
• Crucible tongs: what they are for and how to use them
• Graphite ingot molds and rods in casting
• Metal ingots and casting grain
• Casting