BARNETT
SCULPTURE
- The Lost Wax Bronze Casting Process -
This process is very time consuming, laborious and costly.
Small works take approximately 4 to 6 months to create and life size works can take up to a full year when the Foundry is busy.
- The Lost Wax Bronze Casting Process -
This process is very time consuming, laborious and costly.
Small works take approximately 4 to 6 months to create and life size works can take up to a full year when the Foundry is busy.
BRONZE IS AN ALLOY OF 95% COPPER, 4% SILICON, .02% TIN, .02%LEAD, .06% ZINC
STEPS:
1) CREATE - wax sculpture, large sculptures are cast into numerous sections.
2) SPRUE - attach wax gates, vents & pouring cup - which act like plumbing to the work.
3) INVEST - dip in a liquid ceramic slurry to build up numerous layers of a hard refractory mold.
4) BURN-OUT - an autoclave and hot kiln melt the wax out of the hard mold - "lost wax method."
5) POUR - molten bronze is poured in the empty mold at 2100' Fahrenheit.
6) BREAKOUT - once cool the ceramic shell mold is broken away to reveal the bronze sculpture.
7) SANDBLAST - remove the last traces of the ceramic shell mold that adheres to the bronze.
8) FINISH & CHASE - bronze feeder gates & sprues are cut off and various pneumatic tools.
grind, sand, & polish until the bronze sculpture looks exactly like the original wax sculpture.
9) WELD - numerous sections are welded together and polished smooth.
10) PATINA - various chemicals are applied to the surface both cold & hot to age the metal into various colors. Paste wax is applied to hold the patina color and add a protective polish or shine.
11) BASE - some works are attached to wood or marble bases unless they were designed with bronze bases.
FOR EDITION COPIES:
1) RUBBER MOLD - a flexible rubber is coated over the original piece and a rigid plaster mother mold holds it in place. This is a time-consuming & difficult process which can be costly.
Note: the original sculpture can be made of any material: wax, metal, stone, wood, clay, etc.
2) WAX COPY - hot wax is poured into the rubber mold and allowed to cool solid.
3) CLEAN WAX - the wax is removed from the mold and carefully cleaned to remove all seam lines, air bubbles or flaws.
4) REPEAT PROCESS ABOVE - repeat each step above for each edition copy.
I began working as a Patina Specialist at ARTWORKS Foundry & Gallery in 1985-88. Even after securing a full-time teaching position at Merced College in 1988, I would return to the foundry in Berkeley, CA to cast new works, create edition copies, work on large-scale sculptures and pursue 3D printing enlargement projects. For several decades I kept an art studio right next door, splitting my time between working on new sculptures there and creating waxes from my home studio.
Below: Wax edition copy inside soft rubber mold surrounded by rigid plaster mother mold.
Teaching the Bronze Casting Process at Merced College
Teaching the Bronze Casting Process at Merced College
For 35 years I taught bronze casting in my "SCULPTURE: 3D Foundations" class at Merced College, where I would produce a variety of sculptures each semester for demonstration and lecture purposes with my students. I retired in 2017.
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Pouring molten bronze metal into plaster molds with students.
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