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Lost wax bronze casting
Lost Wax|Make and Mould|Ceramic Shell|Pouring the Bronze|Chasing|Summery|Fake bronzes
This process is known in French as "Cire Perdue" (lost wax). All of Steven's sculptures are cast using the "lost wax" process. All bronze pieces are cast from a wax model regardless of the original material the model was sculpted in usually in clay, plaster or wax.
This is the most precise metal casting technique in existence, ensuring accurate reproductions of the original sculpture and exquisite detail.
"Lost wax" casting dates back thousands of years and is a quite interesting process, while modern methods and materials have improved the technique, it is still an extremely labor intensive and expensive process.
After Steven sculpts the original, a silicone mould is made from the finished piece, and a hollow wax cast is drawn from this mould. Steven personally quality controls every stage of the production, mold making, wax casting, wax chasing, cast metal, metal finishing and patina.
Steven uses specially blended oil and wax based 'clays'. Life models are use for all works, sometimes using a number of models for a single original sculpture.
Because this is the "lost wax" casting process, a mould must be made from the original. This is done by covering the original with a layer silicone rubber and then applying a multi piece plaster jacket.
It may be cut into depending on the size and complexity of the original; it is often cut into carefully selected specific pieces, depending on the size and design of the sculpture.
In the wax stage, a series of layers of wax are poured into the mould creating a 3/16" to 1/8" wall. Molten wax is then "slushed" into the hollow mould and poured out, leaving a hollow wax copy of the original. When cool, the rubber mould is pulled away from the wax.
Then wax duplicate is to be wax chased, repaired, re-worked and finished to the sculptor's specifications. Using a variety of tools and hot soldering irons, mould lines will be removed and any parts reattached. The wax is will look exactly like the original work.
Wax gates, or sprues, are attached to critical points on the piece and the entire gated piece is affixed to a central wax "cup". Prior to creating a ceramic shell, vents are attached within the wax model. These vents are necessary in difficult areas where gas may accumulate such as hips, limbs, and neck.
When the wax is "lost", these gates, will become the avenues for the molten metal to flow into the piece. The vents allow the gas to escape when the molten bronze is poured and will prevent air pockets from forming and exploding the ceramic shell.
The ceramic shell is one of the few materials that can withstand the heat of molten bronze.
The sprued wax then prepared for casting and must be encased with multiple layers of a rock hard plaster-like material called "shell."
This ceramic shell is built up around the wax by dipping it into a slurry, coating it with a fine sand, letting it dry, and repeating this process anywhere from 8 to 14 times.
A core consisting of plaster, ground brick and water is poured into the interior of the wax mould.
When the shell is dry, it is placed in a kiln which melts out the wax inside, hence the name "lost wax." and the ceramic shell is left intact.
This leaves a hollow impression inside the "shell" the cavity left by the melted wax, which is then filled with a molten bronze alloy created especially for art castings.
In the METAL POURING process, the shell is heated in the kiln, and when 1600 degrees, placed in sand for support.The molten metal is poured into the shell at a temperature of approximately 2020 degrees
After the metal cools, the ceramic shell will be removed with a pneumatic hammer, the shell is chipped off and a "rough casting" is removed.Sprues will be cut off and extensive sand blasting will be performed In order to weld it all back together. Reassemble will take place in the WELDING area by carefully realigning and refitting the pieces.
The bronze must now be repaired and finished. Now begins an arduous process known as "chasing" which transforms the "rough casting" into a finished work of art.
Many hours of welding, grinding, sanding and polishing make up the "chasing" process.
Pneumatic tools with an array of carbide burrs, are used in METAL CHASING to grind down the weld areas and re-texture the bronze.
Any imperfections such as air pockets or pits must be brazed with bronze rod, as in welding.
The piece is now polished and ready for its colour to be applied, the "patina." The natural bronze has a dull finish, since bronze comes in a variety of alloys; the patina requires different chemicals and techniques. Chemicals, pigments, heat, safety equipment and a lot of experience are involved.This is applied using torches and special chemical mixes to achieve the colors and hues desired by the artist. The method of application, temperature of the bronze, combination and strength of chemicals, can create an endless variety of patinas.
Next a coating of wax is applied to the surface while it is hot. This serves to protect the surface from oxidation and also gives the finished bronze its luster.In the final step Steven inspects each piece for quality. After everything is to his satisfaction, he applies the unique edition number that marks it as unique and as authentic.
A base is now designed by the artist, cut and polished by a marble expert and the sculpture is finally mounted. The patinaed bronze sculpture is often attached to wood, stone or a combination as a BASE.
The piece is now polished and ready for its colour to be applied, the "patina." The natural bronze has a dull finish, since bronze comes in a variety of alloys; the patina requires different chemicals and techniques. Chemicals, pigments, heat, safety equipment and a lot of experience are involved.
This is applied using torches and special chemical mixes to achieve the colors and hues desired by the artist. The method of application, temperature of the bronze, combination and strength of chemicals, can create an endless variety of patinas.
Next a coating of wax is applied to the surface while it is hot. This serves to protect the surface from oxidation and also gives the finished bronze its luster.In the final step Steven inspects each piece for quality. After everything is to his satisfaction, he applies the unique edition number that marks it as unique and as authentic.
A base is now designed by the artist, cut and polished by a marble expert and the sculpture is finally mounted. The patinaed bronze sculpture is often attached to wood, stone or a combination as a BASE.
Cold cast or "bonded bronze" is the name given to a less costly process. The mould is filled with a plastic resin mixed with bronze powders. The piece is then patinated to the desired finish. The process creates the effect of bronze but is far less expensive, because it is not the real thing.
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