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The process of creating a large bronze statue is complex
and lengthy, involving the artist and several skilled workers.
Several trips to the foundry are necessary to examine and
approve the work-in-progress, from the initial creation of
the waxes to the final welding that assembles the component
pieces into the final product. The following images briefly
document these steps.
Here Janice stands with the initial armature for
Rosebuds. This is welded steel and must be strong
enough to support several hundred pounds of clay,
which are applied over a foam core. The initial
positioning and angles are eyeballed. If incorrect,
the removal of clay and rewelding would be required.
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Two days later the figures are rough yet discernible.
At this point about 400 pounds of clay have been
applied. |
After another week the figures are filling out
yet the details are still lacking. |
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Several weeks later the figures are very well
definied. The precise detail which creates the
interaction between the figures and makes them
come alive will take many more hours. |
When the clay figures are finally finished, the long and
tedious path to the final bronze product begins. Many
of the necessary operations involve skilled workers who
perform their tasks under the watchful eyes of the artist.
Still at the artist’s studio,
the first of two molds is created by coating the clay figures
with a semi-liquid rubber compound, usually in three separate
applications. When dry, the rubber is covered with a plaster compound
to provide a rigid backing. The mold is actually done in several sections,
carefully chosen by the artist to correspond to and facilitate the casting
of the bronze, which is also done in sections. For example, a figure's
head might be molded in two sections, front and back, or a figure's lower
leg (knee to foot) might be molded in two sections, also front and back. In
the case of Rosebuds, the five figures were molded in 69 separate sections.
Coating the clay with rubber.
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Plaster covers the rubber. |
Once the plaster has hardened, the mold is carefully removed,
section by section. Each section is then cleaned
and numbered and a diagram is prepared for the foundry
showing the location of each section on the sculpture. The
molds are transported to the foundry for the remaining
operations.
The first use of the molds involves filling each by brushing
on three layers of heated (liquid) wax. When hardened,
each wax piece is delicately removed. When all the
waxes are completed they are assembled to form a duplicate
of the original clay form. At this point the waxes
are carefully examined by the artist for any flaws or deviations
from the original. Imperfections may be corrected at this
step by directly reshaping the wax. The sectioning
used for making the original molds is reevaluated, to determine
if a different arrangement might be more suitable for the
casting process. The waxes are then cut apart accordingly.
Mold sections after cleaning and numbering.
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Assembled wax figure. |
Each wax piece is dipped once a day, for eight days straight,
into a liquid bath. This liquid hardens around the
wax to form a ceramic mold, a material that can withstand
the temperature of the molten bronze. The dipping
is controlled and engineered to produce ceramic molds that
will allow a uniform flow of the molten bronze within the
cavity, as well as uniform cooling. At this point,
the ceramic molds still contain the wax which initiated
the dipping process. This wax is "burned" out
prior to using the molds by heating each mold in a kiln
to about 1,000 degrees F.
Pouring the molten bronze. |
Each mold may now be placed in a bed of sand for sufficient
support, ready to receive the carefully poured molten bronze. An
undetected weakness in the mold could cause a small explosion
and runoff of the molten bronze onto the floor. If
this occurs, the section in question must be redone, going
back to the creation of the wax from the original mold. The
reason for casting a work in sections is that smaller pours
are statistically more successful. After cooling
for up to three hours, the mold is chopped away from the
bronze, and any excess metal (sprue) is removed.
When the casting is complete, the several bronze pieces
must be assembled, much like a three-dimensional jigsaw
puzzle, and welded together. Each seam must be blended,
or chased, to disguise the appearance of the seam, and
to exhibit the surface detail of the original clay form. For
standing human figures such as we see in Rosebuds, heavy
steel rods are secured within the legs, and extend outward
about 12 inches. These will be used with cement
to anchor each sculpture. The foundry prepares
a template for use at the installation site.
The last operation involves the patina, the coloration
on the surface of the sculpture. It should be noted
here that "raw" bronze is very shiny and gold-like
in appearance. As bronze oxidizes rapidly, it is
nearly impossible to maintain that luster on outdoor monuments,
so patinas are used. The artist considers the surroundings
of the installation site to choose one or more colors for
the sculpture. Various chemicals, when applied with
heat, produce subtle color changes in the bronze. With
the completion of the patina, the sculpture is coated with
a protective wax or lacquer, and is now ready for installation.
The finished work is seen below.
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