Original Sculpture
An artist sculpts a piece in the media of his/her choice, most often in clay or stone.
Creating a Mold
A mold of the sculpture is created using several thin layers of silicone rubber and a plaster housing.
Wax Pulling, Chasing, and Spruing
Hot liquid wax is painted or poured into the mold, allowed to cool and harden, and released from the mold.
The wax duplicate is tooled by a foundry technician, who repairs any flaws in the wax using an assortment of
hot tools and small hand tools. The piece is then moved to “spruing,” where wax rods are added to the piece,
forming where the bronze will flow into the artwork.
Investing the Wax
A ceramic shell casing, nearly 1/2” thick, is built up around the sprued wax by repeatedly dipping it in a
slurry bath, then in a silica sand tank, and then allowing it to dry. Once the piece has been properly invested,
it is heated in a kiln, where the wax melts and a void is left where the wax duplication once was.
Casting
Bronze ingots are placed inside a graphite crucible heated to approximately 2000 degrees in a furnace. The molten
metal is removed from the furnace, poured into the empty investment shells, and left to cool.
De-vesting and Cut-off
After the casting has cooled, the investment is removed using hammers, chisels, and sand blasting, and the bronze
that filled the sprue channels is cut off.
Assembly and Chasing
Now that the pieces are in metal, the foundry staff use welders and various power tools to repair any imperfections
that may have occurred during the casting process. On larger sculptures, several castings may be welded together,
with the seam needing to be chased back to look like the original piece of art.
Patina
Once the sculpture is finished in metal, chemicals are applied to the surface of the metal, which has been heated
using a torch. The chemicals react with the bronze and oxidize in various colors and patterns, determined by the
temperature of the metal and style of application. The patina is sealed with either lacquer or a coat of wax to
preserve the color.
Finishing
As a final step, the sculpture is often mounted to a stone, wood, or metal base. Once completed, it is boxed and
shipped to its final destination or picked up by the artist.