Home Casting

Synopsis

Casting is the art of turning liquid metal into a desired shape by pouring it into molds and letting it harden. There are two main aspects to casting: melting of the metal of choice and creating a suitable mold. The properties of the resulting cast are determined by the base metal and processing conditions while the quality of the cast is determined by the mold and the compatibility of the mold material with the metal. The forge can be a simple heated vessel or an elaborate structure with multiple layers of insulating material. Insulation needs to be durable and is usually crafted for the purpose. Examples include fire brick and refractory clay.

Metal: The primary challenge with melting the metal is keeping the melting container (crucible) hot enough to melt the raw material and keep it liquid. Additionally, the melting point must be exceeded enough that metal melts at physically relevant rate and stays liquid when removed from the heat and poured into the mold so it can take the mold's shape. Therefore, the lower the melting point of the metal the easier, and less expensive, it will be to work with. Aluminum is a common choice because it has a lower relative boiling point to most common metals. It is also ubiquitous in the form of aluminum cans. 

Safety: This experiment uses extremely high heat and liquid metals. It is extremely dangerous. Do not attempt without professional help. 

Equipment

• Fire
• Heat source (propane tank)
• Fuel hose
• Fuel regulator
• Torch (venturi style)
• Furnace
• Insulation (fire brick, ceramic blanket, refractory cement)
• Metal shell
• Crucible (ceramic or metal)
• Tools
• Tongs
• Slag remover
• Safety
• Heat resistant gloves/suit
• Face shields
• Molds
• Plaster
• Sand/foam
• Bonded sand

Instructions

1. Build forge starting with shell and crucible, putting insulation in between. Look here for a more detailed description of forge building.
2. Insert torch into forge heating slot
3. Open fuel supply and ignite torch.
4. Insert crucible. Close forge and allow to heat.
5. Check temperature by adding a small amount of material and observing if it melts.
6. Once sufficient temperature is reached fill the crucible with cans. Pressure can be applied to force the cans into the hottest part of the forge if using a metal crucible. If a ceramic crucible is used do not apply pressure. Return crucible to forge and allow to heat.
7. Add more cans as needed until enough metal has gathered.
8. Briskly remove crucible from forge and pour metal into mold.
9. Allow mold to cool. Once cooled remove figure from mold.