The sculptor creates an inner skeleton called an armature to support the sculpture. A combination of wire and metal rods are used for the main support and polystyrene, polyurethane and even news paper is used to make up some of the bulk of the inner sculpture to make it as light as possible for transportation. The Sculptor then applies his preferred medium of clay to the armature to create his master piece. The two most common clays used is oil based and water based clay. Working from life, video footage and photographs he uses his knowledge of anatomy, skin texture and movement to create the essence of the animal, bird or human figure in motion.
The Cire Perdu – Lost Wax Process
Silicone rubber is used to make a perfect negative, or mould of the original sculpture. The rubber mould is supported by a mother mould of plaster or more commonly used fibreglass or M1. Hot wax is poured into the rubber mould to create an even wax of about 5mm thick. After the wax cools, it is removed from the rubber mould, leaving an exact copy of the original clay sculpture. The wax is chased giving a detailed wax pattern identical to the artists original. Wax sprue bars are then attached to the wax sculpture creating a feeding system for the molten metal to flow into the wax pattern.
The complete hollow wax sculpture is dipped into a thick ceramic mixture. This is done repeatedly over an extended period of time until a strong wire reinforced ceramic shell is formed over the wax system. The ceramic shell is placed in a burn out kiln, which hardens the ceramic shell with the wax system being burned out simultaneously. The ceramic shell becomes the final mould (or negative), when the wax system is melted out or “lost”.
Next, the now empty ceramic shell is heated, while the bronze is melted. Bronze is heated and melted down at 1200 degrees Celsius. The molten metal is then cast into the heated ceramic mould. The bronze thus replaces the lost wax system. Once cooled the ceramic shell is removed and the sprues are cut off. The sculptures are sandblasted removing any ceramic remaining on the casting.
The sculptures are then welded and chased, restoring detail to the sculpture and giving a detailed representation of the artist original. The sculptor and foundry produce a limited series of the sculpture. Each original is signed and numbered by the artist to ensure collectors value and to ensure copyrights. The final process of finishing the bronze piece is the patina. A patina is done as to speed up the aging process of the bronze. The sculpture is heated and various chemicals are applied to the surface of the bronze creating different colours, patterns and effects, specifically applied to the artists requirements.
Finally, the sculpture is mounted on a base and polished, ready to be exhibited!