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The Foundry Process
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Artist Osprey Orielle Lake will create Mari-Waters of Life at Artworks Foundry in Berkeley, California.
The process of casting bronze is an ancient art dating back to ancient Egypt, Greece and China. Centuries ago, artists who sought to retain all of the detail in an original sculpture when casting it in bronze developed the "lost wax method" of bronze casting.
First the artist models the sculpture using clay, wax or any substance that can be modeled. From this original "pattern" a rubber mold is made, enabling every detail to be captured. The rubber mold is cut into several sections to assure the clean removal of the wax "positive" which is created from the pouring of liquid wax into the rubber mold.
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These wax "positives" are then cleaned and perfected each time a new numbered piece is cast. The wax positives are encased in a secondary "throwaway" mold, which is made with a liquid ceramic-fused silicon sand mixture. Approximately ten or more coats of the silicon mixture will be applied over the wax taking five or more days. The ceramic material is solidified into a firm mold by baking in a kiln, and the wax is then simultaneously melted out. It is now safe to remove the silicon mold from the heat and pour in the molten bronze metal. The bronze is heated to 2,000 degrees Fahrenheit before it is poured into the ceramic mold. The most commonly used bronze today is an Admiralty standard metal of 88 percent copper to 10 per cent tin and 2 per cent zinc.
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After the pour, the bronze is cooled and the ceramic mold is broken away from the bronze with hammer, chisel and heavy equipment. The various bronze sections are then welded together and imperfections are corrected in the metal casting.
At this phase in the process the bronze is in rough form. It is sandblasted to clean the surfaces. When the metal is perfected and the welds are cleaned, the sculpture is prepared for patina, which is the coloring process. Color variations within acid patinas are achieved by applying various chemicals one over another, while heating the bronze to different temperatures. A good patina requires many hours to apply.
The number of sculptures produced are limited by the artist and are called "Editions". The entire process of pulling a new wax from the rubber mold must be repeated for each numbered piece. Every casting requires the same detailed expertise. Many different finishes can be achieved at this point through the use of power tools and sand papers.
Additionally, Osprey Orielle Lake has developed many special metal finishing techniques that result in a unique presentation. She also completes her sculptures with an application of a product which prevents tarnishing and eliminates the need for polishing.
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If you would like to see another international monument project by artist, Osprey Orielle Lake, please visit the Cheemah Monument website at:
www.cheemahproject.org
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