Casting Bronze Sculpture
The "Lost Wax Process".

1. Original Sculpture

The original sculpture is created by the artist using clay, wax, or plastilina. Depending on size, sculpture can be cast as a whole or cut into pieces.

2. Creating the Molds and Wax

A rubber mold is made directly onto the original sculpture. A plaser "mother mold" is made encasing the rubber. Molds are removed, reassembled, and filled with melted wax. The hardened wax is removed and carefully hand-finished to replicate the original.

3. Spruing the Wax

Wax rods are attached to the sculpture (called gates and sprues) in a manner resembling arteries. These gates lead to a wax funnel at one end of the rod.

4. Investing the Wax

Hardened wax is first dipped into a liquid "shell" vat. While still wet, it is slowly lowered into a dry silica-sand, forming a rigid shell. This process is repeated in layers, creating a hard plasterlike shell.

5. Burning Out the Wax

The wax, with its heavy shell coating, is now steam heated, melting out all of the wax, leaving only a hollow shell. This is where the "lost wax" term applies.

6. Pouring the Bronze

While the bronze bars are heated to liquid form, shells are baked to a ceramic-like stone. Melted bronze is then poured into the hollow cavity within the shell.

7. Revealing the Bronze

Once the bronze is cool, the shell is broken away with hammer and chisel. Bars and funnel are also removed at this time.

8. Sandblasting

Any remaining shell is removed by two stages of sand-blasting; first with coarse, then with fine sand.

9. Chasing the Bronze

Imperfections to the surface, as well as marks and scars left when removing the bars and funnel are repaired in a process called "chasing."

10. Assembling and Welding

The sculpture is reassembled and welded into correct position. Welded seams are again "chased" by the artist until the bronze is identical to the original work.

11. Patiniation

The coloration of the bronze is achieved by applying heat and chemically controlled tarnishing to the metal. Chemicals can be applied, sprayed, or brushed on in various degrees of heat known as "applying the patina."