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The creation of a bronze sculpture involves many steps.
- The process begins when Marie Christine makes the clay original.
Great care is taken during this step because every detail will
be transferred into bronze later.
- When the clay model is perfect, several layers of liquid rubber
is brushed onto the clay and allowed to harden, or cure.
- The clay-filled rubber master mold is then covered in plaster
so that the rubber mold will be supported when it is filled
with molten wax in the next step. The plaster shell is made
in pieces so that it can be separated and the contents removed
from the mother mold.
- The rubber mold is then removed and the clay original is released
from inside the rubber. Most of the time, this destroys part
or all of the clay model.
- The rubber mold is placed back inside the plaster shell and
filled with molten wax, creating the wax master. It is this
master which will provide all the detail in the final bronze
casting.
- The wax model is cleaned and any imperfections are repaired
(chased). Air bubbles are filled in and details are sharpened.
Now the final casting can procede.
- At the foundry, the wax model is inspected and prepared for
casting. Wax rods are added, which will serve as entrance passages
for the molten bronze and exit passages for the air and gasses
inside the mold. This is called spruing the wax.
- The finished wax is then painted with a plaster and silicone
mixture. The process is repeated several times to build up thickness
and strength. The mixture is allowed to dry in between applications,
forming a shell around the wax. This is the final mold.
- The final mold is placed in a kiln and heated. The plaster/silicone
mixture hardens and the wax melts and is vaporized (lost). This
is where the term "lost wax casting" comes from.
- Liquid bronze is poured into the ceramic mold and allowed
to cool.
- The ceramic mold is broken away, leaving the bronze figure,
which is then cleaned and chased.
- The piece is then polished and a patina is applied.
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