The Process
Making of 'Late for the Interurban'
The art of lost wax bronze casting (cire perdue) remains relatively unchanged for many thousands of years. For the bronze the work is essentially sculpted three times, once as an original (clay, plaster, stone, wood) from which a rubber mold is taken; once as a hollow wax pattern and finally as a bronze. The casting process usually goes as follows:
1. An original is sculpted then cut up for making the production molds.
2. A flexible rubber mold with rigid 'jacket' or 'mother mold' is taken from the original's parts.
3. A wax pattern is produced by sloshing in and out several layers of wax into the mold to a wall thickness of 1/8" to 1/4".
4. The wax pattern is reworked (chased) and cut up further. Wax bars and cups are added for removal of the wax and channeling the molten bronze.
5. The wax pattern is 'invested' in a material that can withstand the heat of the molten bronze at 2200 degrees. Typically this material is a ceramic based or plaster based.
6. The wax is burned out of the investment in a kiln leaving a clean negative for the metal.
7. Bronze is melted and poured into the investment.
8. The investment is knocked off, the bronze casting is cleaned, the now bronze bars and cups are cut off.
9. The bronze sculpture is 'built', welding the parts together, sanding down the seams, and tooling in the details.
10. The chased metal is cleaned with a sandblaster and the many variations of 'patina' is applied, the bronze then sealed and finished.
Modern advancements include welders, molding compounds and the investment. Digital technologies have aided greatly in the conceptual and production of the original. Using as an example of this complex process is 'Late for the Interurban', a larger than life tribute to the J. P. Patches show located in the Fremont neighborhood in Seattle, taking the commission through conception to dedication.
1. An original is sculpted then cut up for making the production molds.
2. A flexible rubber mold with rigid 'jacket' or 'mother mold' is taken from the original's parts.
3. A wax pattern is produced by sloshing in and out several layers of wax into the mold to a wall thickness of 1/8" to 1/4".
4. The wax pattern is reworked (chased) and cut up further. Wax bars and cups are added for removal of the wax and channeling the molten bronze.
5. The wax pattern is 'invested' in a material that can withstand the heat of the molten bronze at 2200 degrees. Typically this material is a ceramic based or plaster based.
6. The wax is burned out of the investment in a kiln leaving a clean negative for the metal.
7. Bronze is melted and poured into the investment.
8. The investment is knocked off, the bronze casting is cleaned, the now bronze bars and cups are cut off.
9. The bronze sculpture is 'built', welding the parts together, sanding down the seams, and tooling in the details.
10. The chased metal is cleaned with a sandblaster and the many variations of 'patina' is applied, the bronze then sealed and finished.
Modern advancements include welders, molding compounds and the investment. Digital technologies have aided greatly in the conceptual and production of the original. Using as an example of this complex process is 'Late for the Interurban', a larger than life tribute to the J. P. Patches show located in the Fremont neighborhood in Seattle, taking the commission through conception to dedication.
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