•   Curtis Perry MD puts the finishing touches on the clay original that will become come a bronze sculpture. His son, then age 4, poses in the background.


    Curtis Perry MD puts the finishing touches on the clay original that will become come a bronze sculpture. His son, then age 4, poses in the background.

    I am often asked by people who have just finished looking at my sculptures, how a bronze sculpture is made. The answer is a multi-step process that traces back to ancient civilizations while employing the latest in manufacturing technologies.

    The Original Sculpture- A bronze sculpture never begins in bronze. Typically the original sculpture is first made from clay, although any material that can be molded or carved can be used.

    The Master Sculpture- From this original piece a mold is made. Into this mold a material, usually plaster, that will be harder and more durable is poured. This second sculpture is referred to as the “master”. Often some final fine details are added on the master.

    The Wax Sculpture- A new mold is then made from the master which is called the “working mold”. Once the working mold hardens, wax is then poured into it. When the wax cools it is removed. The new wax sculpture then has wax tubing or “gating” attached to it so that the molten bronze can flow evenly to all areas and gases can escaped. The wax sculpture and attached gating is then coated or “invested” in ceramic or plaster material. Once the “investment” hardens, the wax is then melted or “burned out” of the investing material leaving a hollow cavity “negative” of the sculpture and its gating. Because the wax sculptured is gone or “lost” the process is referred to as the “lost wax” technique.

    Finally the Bronze Sculpture- Molten bronze is poured into the hollow cavity that once held the wax and gating. Once the bronze has cooled, the investment is cleaned off the bronze and the gating is removed. Any final surface texturing such as polishing is then performed. Removing the gating and any final texture work is referred to as “chasing”. Finally, dyes or chemicals are applied to create the desired surface color(s). The when the chemicals chosen chemically react with the metal the final surface is referred to as the “patina”.

    Some Final Thoughts- The lost wax technique was used by the ancient Greeks and Romans to create all their bronze sculptures. The ancient Chinese also used sand mold technologies but that’s a whole other story. Ceramic investment or “Ceramic Shell” is a modern technology that is also used in precision manufacturing of objects such as jet engine parts. The process is actually far more detailed than what I described above. For instance only the smallest sculptures are cast solid and in one piece. Stable cores must be designed to to keep the walls of the sculpture an even thickness and the multiple pieces must be carefully separated and keyed so the when they are reattached the final sculpture appears seamless.

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