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Creating an artwork in
bronze is a time consuming process. If costs seem high, this is due to the
large number of hours necessary to create the work. Despite new
developments in mold making and casting technologies, these processes
remain labor intensive.
The steps explained in
the following are repeated for each bronze edition created, (with the
exception of the molding).
First step: Creating
the original sculpture using any of a variety of materials including:
Clay, wax, wood, plaster, or even found objects.
Second step: Molding
the original by enveloping the sculpture in latex /urethane or any number
of materials to produce an exact copy of the piece. The original is
removed from the mold, leaving an exact negative of the original. A large
or complex sculpture may require being disassembled and multiple molds
having to be made.
Third step: Making an
exact copy in wax, by pouring molten wax into the mold for a specific
amount of time, creating a 3/16 inch thick hollow shell of the original.
This wax is then “dressed” meaning removed from the mold and re detailed,
defects removed (such as mold seam lines voids, etc.) and depending upon
the size the of the sculpture, either reassembled, or cut into various
pieces for better casting.
Fourth step: Spruing
the wax means creating channels (called gates) to the copy as well as a
pouring spout. Everyplace there is wax will be replaced by bronze.
Fifth step: Creating a
ceramic shell around the wax is done by repeated dipping into a slurry and
coated with various grades of silica sand. Between each dip, the shell
must dry (cure) completely before it can be coated again. This step
usually takes a week to complete.
Sixth step: The wax is
then burnt out of the shell, (hence the name lost wax process) creating a
hollow ceramic shell mold.
Seventh step: Bronze
casting is finally ready to take place. The ceramic shell is heated and
immediately the molten bronze (1800-2100 degrees Fahrenheit) is poured
into the shell.
Eighth step: Knock out
– when the bronze has cooled the ceramic shell is then carefully knocked
away, sandblasting may also be necessary to remove all traces of the
shell.
Ninth step: Removal of
the gates is done by using a plasma torch or grinding tool.
Tenth step: Welding
and chasing the metal may now take place. At this time if the sculpture
was cut into pieces (for easier casting) they are welded back together and
all defects and welds are re-detailed (texture matched etc.) the sculpture
is then sandblasted, and cleaned.
Eleventh step:
Patination is the process where the bronze is heated and a variety of
chemicals applied to color the sculpture. Varying strengths of chemicals
and varying temperatures create subtle color changes to the sculpture.
This step is quite an art in itself.
Twelfth step:
Finishing the sculpture entails waxing the surface, or coating with metal
lacquer to protect the patina from the elements, and mounting the
sculpture on an appropriate base (plinth) for display.
With the labor and
skill of many artisans, a fine art bronze is created to last more than a
few lifetimes. |
