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The Bronze Casting Process

The Bronze Casting Process

Posted by on Apr 3, 2011 in Open Category |

A steel armature is fabricated that will function as a ”skeleton” to hold the weight of the clay
The piece is sculpted using an oil based clay
The piece is worked and reworked until both the artist and client are pleased
The finished life-size sculpture
Thin sheets of metal are used to divide the sculpture in to a predetermined number of sections
A latex rubber is applied to the clay sculpture.  5-6 coats are used to build up a sufficient thickness
The molds are backed with plaster, which will give rigidity and support to the rubber
The plaster pieces are removed and the latex is cut down the center to create a two section mold
A finished set of Molds
The molds are coated with wax to create a copy of the clay original
Wax is poured in, the mold is rotated to evenly coat, and the excess wax is poured out. This will create a hollow replica
A finished wax being removed from the mold
One finished wax piece
The pieces are touched up and wax runners and a wax cup are attached.  The cup and runners will later act as funneling system to enable the bronze to reach the piece
The pieces are coated in a liquid ceramic and allowed to dry.  This will be repeated 7-8 times to build a thick ceramic shell.  The shell becomes another mold
Finishing the first coat
The piece is next coated in sand. This will help dry it quicker and add mass to the ceramic
The ceramic is chipped away from the bottom of the cup gaining access to the wax.  The piece is heated and the wax melts, leaving a hollow ceramic shell
The mold is now hollow and ready for bronze to be poured in
20 lbs. bronze ingots will be melted and poured into the shells
The bronze is melted in a crucible in a furnace to over 2000 degrees
The ceramic shell are also heated, to prevent them from shattering from the shock of the molten bronze
The shells are removed from the oven and place in a sand filled box with the cup facing up
The cup acts as a funnel and the runners carry the bronze to the piece
Once cooled, the ceramic shell is chipped away. Then the cup and runners will be cut off
A finished set of bronze pieces ready to be reassembled
Using heli-arch welders the bronze pieces are welded back together.  The sculpture is ground and polished to create a seamless finish
The sculpture is heated and treated with chemicals that oxidize the bronze changing its color to the desired effect
The finished piece is not only beautiful but strong and durable able to last generations!
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