|
The Lost Wax Process
Original Sculpture
The first step begins with the Artist creating an original sculpture. This is usually
created from wax or clay, although sometimes other materials are used. Sometimes several
materials are used together.
Rubber Mold
Because this is the "lost wax" casting process, a mold must be made from the original.
This is done by covering the original with several layers of silicone or rubber. This
flexible mold captures every detail of the artist's original, and is one of the most
critical phases in the bronze process. Depending on the size and complexity of the
original, it is often cut into specific pieces. The mold is then covered with a multi
layered plaster jacket.
The Wax Casting
The molds are then used to form wax figures: molten wax is poured into the rubber mold.
A series of layers of wax are poured into the mold and "slushed" into all the little
spaces in the mold. When the wax is cooled, the rubber mold is pulled away from the wax.
The wax duplicate is removed from the mold, and a trained artisan hand finishes the wax
pattern to original perfection. Each wax casting is treated as if it were an original
work of art.
Sprung
Wax rods, called gates, are attached to the wax pattern to allow the even flow of molten
metal and to alleviate the trapping of air and gas.
Ceramic Shell
The ceramic shell is one of the few materials that can stand the heat of molten bronze.
Several layers are applied creating a stable mold which is allowed to cure for several
days. When the shell is cured, the shell is fired in a kiln. This bakes the shell and
eliminates the wax, leaving a cavity in its place. (Thus the term "LOST WAX")
Casting
After being heated in a kiln, the molten bronze is poured into the form, at a temperature
of approximately 2100 F. (Bronze is an alloy of 95% copper, .02% lead, .02% tin,
.06% zinc, 4% silicon.)
Breakout
After cooling, the ceramic shell is carefully broken away, revealing a rough casting.
Sprues will be cut off and extensive sand blasting will be done in order to prepare it
for welding back together. Then by grinding, chasing, sanding and polishing, all areas
are blended back together to make the bronze look exactly like the sculptor's original
work.
|
