Creating a Bronze Sculpture
1. The original sculpture is created from oil-based clay over a wire frame (armature).
2. A flexible mold is created by brushing several coats of rubber onto the clay sculpture until a uniform thickness of about ¼ inch is reached. After the rubber mold solidifies, plaster is applied over the rubber surface. This dries to form a rigid shell over the rubber called the “mother mold.”
The original clay sculpture is removed from the mold.
3. Hot wax is poured in and out of the mold repeatedly until the desired thickness is formed. Once the wax is cooled, the mother mold and the rubber are removed.
4. The wax is now a hollow replica of the original sculpture.
5. A sprue system (wax rods that allow the wax to run out and the molten metal to flow in) is attached to the wax sculpture.
6. The wax sculpture is dipped into a ceramic shell slurry (investment) from six to ten times (allowing each coat to air dry) building up a layer of about 3/8 inch around the wax and its sprue system.
7. The investment-covered wax is placed in a “burn-out” kiln where the wax is rapidly melted out and the investment becomes a hard shell. The shell is then able to withstand the pressure of the molten metal.
8. The bronze is heated to 2000°F and poured into the ceramic shell.
9. When the shell is cool (several hours to overnight) the cast is removed (de-vested) by beating with a hammer, sand blasting, and/or scrubbing with a wire brush. The sprue system is removed from the casting.
10. The bronze sculpture is heated and a patina is obtained by applying various chemicals.
11. An even coat of wax is brushed over the entire hot bronze. It is then cooled to room temperature and buffed with a soft cloth.
The bronze sculpture is now complete!