Cast bronze – art that is meant to last forever
This mysterious alloy of copper and tin has been held in high esteem from time immemorial because, like other precious metals, it lasts for a long time. Ever since the Bronze Age, art has been driven by a desire for immortality. Hence it was that much more important for art to survive. Bronze fulfils this wish and thus bronze art has been a part of human history from antiquity to the present day.
When inspiration takes shape
At the beginning of the creative process is the artist’s idea. His original model goes through the hands of craftsmen in many individual steps before it is ready for casting. The lost-wax method is based on a tradition that is thousands of years old. More than twenty different processes are needed to make a finished work of bronze art from the original model.
The technique of mould construction
In order to obtain the positive wax model, which corresponds exactly to the original model and can later be rendered, you first have to make a flexible negative mould. To do so, each half of the original model is covered with clay plates which are then covered with plaster. When these “plaster supporting shells” dry, the clay layer is removed and both shells are again placed around the model. Then liquid gelatine or silicone is poured into the hollow spaces between the original model and the plaster.
The negative mould is now finished and true to the original. The two halves of the mould are put together and hot wax is poured in. A few minutes of cooling produces a solid layer of wax. This wax copy is retouched by the artist again and then sprued. Next, the wax model is covered with plaster fireclay and burned out in a kiln at 600°C for about seven days. This allows the wax to melt and run out, and the hollow space is dried. Now comes the decisive moment in the casting process: the liquid bronze that has been heated to about 1,250°C in a crucible furnace is poured into the shell, where it finds its way into the hollow spaces left by the wax. The bronze is allowed to cool slowly for three to four days and then the clay shell is shattered.
Punch and chisel bring the object to life
First the blank is cleaned and its surface quality assessed. After the chaser has separated the sprue and air outlet channels, and has welded together sculptures that consist of more than one part, he very carefully reworks the surfaces with a chasing iron (chasing tools) or a chisel, file, grinding and polishing tools. Each detail, no matter how fine, is accentuated and the special features of the object are highlighted. The result is a living, expressive artwork that corresponds exactly to the artist’s original model.
The art of patinating
Patinating is the last major step in the process. To this end, traditional patination solutions, the recipes of which have been handed down through the ages, are used. The art object is first dipped into a patina bath for a specified period. Then additional patination solutions are applied by hand and burned in with a gas flame. Each artwork is distinguished by slight nuances in its patina. Now the bronze is thoroughly cleaned and waxed. The artwork is complete – made to last forever.