How to Cast Metal Figures

Take a block of wax and carve out the shape of your metal figure with a carving knife. The finished result might depend on your carving skills, but a good methodology to bear in mind is carving out the rough shape first and working your way in steps toward progressively finer detailing. An alternative method would be to take an existing metal or wood figure, and create an impression of it between two blocks of soft clay which you then separate, pouring melted wax into each side of the impression. You would then remove these wax half impressions and gently melt them together so that they are smoothly fused.

Take your wax sculpture and surround it with a clay mold. Press the clay firmly to it so that there are no open gaps between wax and mold. While applying the clay, make sure you create a funneled passage on the top of your wax figure for the metal that will be eventually poured in, and attach a small wax stick to your sculpture's bottom. Surround this in clay as well, leaving only its tip exposed, and set aside your clay-covered wax so the mold can dry.

Place your clay mold containing the wax in a hot kiln and leave it there to harden by baking. During the process, the wax inside it will melt and flow out through the hole in the bottom that was created by the melting of the wax "stick" you had attached to the sculpture's wax positive. While the clay is baking and losing its wax interior, you should melt a sufficient quantity of your favorite metal in a crucible that you have placed in a furnace. Good metals to use include tin, aluminum, lead, silver and bronze. All of these have relatively low melting points and this makes them easy to deal with. Give your metal time to fully liquefy in the crucible by keeping the temperature consistently hot.

Remove your clay mold from the kiln and place it in a bucket of sand; sink it slightly into the sand so that it's solidly entrenched. Now, very quickly, while the clay mold is still hot, remove your crucible containing the liquid metal from its furnace with some long blacksmith's tongs, and pour its contents through the funnel opening you had previously made in your mold's top. Pour until the metal fills the mold completely and reaches near the top of the funnel. Some liquid metal will drip out through the hole at the bottom of your mold, but the amount should be minimal as long as the hole was thinly made.

Allow the metal-filled mold to cool for at least an hour, preferably longer, before breaking the clay away. You are now left with your metal figure. You should use an angle grinder to remove the protruding bits left as the two extended holes in the clay original filled with liquid metal. You may now polish your figure down and clean it.