JANICE TRIMPE | Art as Large as Life

From Clay to Bronze

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.




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.



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.




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.





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.


Janice Trimpe ~ Art as Large as Life