How to Do Bronze Casting

Bronze casting is an art that has been practiced since the eighth century. Also called the "lost wax method" the artisan creates a wax mold of sculpture that is melted away and replaced by the molten metal. A painstaking process, it requires much patience and skill. These steps will help you learn how to do bronze casting.

Instructions

Create a Wax Model

1. Make an exact replica of the final bronze sculpture out of wax when bronze casting.

2. Choose the wax combinations you prefer. In Bangladesh, artisans use a combination of 40 percent bee's wax and 60 percent paraffin. These percentages can vary.

3. Create larger portions of the sculpture such as torsos, heads or arms with separate wax molds.

4. Shape finer details in the wax molds with a heated file.

5. Assemble the wax model, ensuring that all of the pieces of the model fit together properly.

Form the Mold

1. Make a fine solution out of white China clay and water. The solution should be fine enough to be able to pick up the finer details of your bronze sculpture when you are bronze casting.

2. Apply about a half an inch or so of the China clay/water mixture to the outside of your wax model.

3. Create passageways in which the bronze will flow when bronze casting. Poke holes in the bottom of the clay-covered model after it's dried.

4. Coat the outside of your clay-covered model with rice husk, sand and clay. This coating makes the mold thicker when bronze casting.

5. Add small reservoirs over the openings where you'll pour the bronze to prevent messy spills and allow you to pour the molten metal more precisely when bronze casting.

Cast the Mold

1. Place the bronze in crucibles and melt the metal until it's molten in a furnace.

2. Pick up the crucible with forceps once the bronze has reached the proper temperature, approximately 1800 degrees F, and pour the molten bronze into the openings into the bottom of the mold.

3. Allow the mold to sit for three hours or so, until the bronze cools.

Finish the Bronze Sculpture

1. Chip the outer layers of clay and sand from the bronze sculpture when bronze casting. Do this gently and carefully, so as not to cause defects in the sculpture itself.

2. Repair any defects caused in the casting process, such as gaps caused by trapped air. Gently file the bronze sculpture to bring out any of the fine details as needed.

3. Sand and buff the bronzed sculpture when bronzed casting to give it a smooth finish.

4. Remember that you need patience and a gentle, precise touch to create bronze sculptures when bronze casting. A hasty stroke with the file can produce a blemishing flaw in your final work that might be difficult to repair.

Resources

• Lotus Sculpture discusses bronze casting.
• Galica discusses bronze casting.