The lost wax method of casting, is the process Kathleen Zimmerman uses to translate her clay or plaster originals into bronze sculpture. This method of casting was first used by the ancient Chinese and Egyptians to create ritual bronzes, or small figurines, and then by the Greeks to create life-sized bronze castings. Zimmerman’s artwork may be contemporary, but are made using this ancient methodology.
The images below are of Kathleen Zimmerman’s latest sculpture that were cast in bronze. Shown In the following order: Bear Hug {plaster), Counting Sheep - Couple (clay - both sides and plaster pair), Moon Rabbits - Full Moon (plaster pair), Community Spirit - Meeting (plaster pair) and Farm Labor (plaster).
The most important part of this process is creating the original form that will translate well into bronze. When this is accomplished, a rubber and plaster mold is made from the clay or plaster sculpture so that a bronze copy can be produced. Zimmerman makes her own molds from her clay sculpture or plaster originals and then sends these molds to an art-casting foundry. The master foundrymen use her molds to make the bronze castings. The foundry that Zimmerman is currently working with is Lands End Sculpture Center.
The images below showcase Lands End Sculpture Center in Paonia, Colorado and Zimmerman Fine Art Studio in Willington, Connecticut. Lands End Sculpture Center has years of experience in the lost wax method of casting as well as a personal connection with the artist, which explains why it’s her foundry of choice. This age-old method of casting begins with pouring hot wax into the mold, creating a wax sculpture. The wax sculpture is then spurred and chased. Spurring is adding wax funnels, while chasing is fixing any imperfections in the wax. Then the wax and spurs are coated with a number of layers of a ceramic mixture to form a shell. Once the shell is complete, it is heated in order to harden the ceramic shell and melt the wax out. This step in the process is why this type of casting is called the lost wax method. Then molten silicon bronze is poured into the empty shell, which creates the bronze casting. After the shell and bronze cool, the shell is broken off and the metal spurs are cut off. Finally, any welding that needs to be done to connect separate pieces to make a complete whole or to fix any imperfections is carried out. When this work is finished, the whole sculpture is returned to Zimmerman Fine Art Studio.
The images above are of Zimmerman’s artwork going through the process. We are including images of the originals to help you spot them. These images include: the spurring of the wax of Bear Hug, a spurred wax of Farm Labor (upside down), the making of ceramic shells (Farm Labor up front, Bear Hug then Moon Rabbit on left and Community Spirit on right), after the wax has been melted out of the ceramic shells (Counting Sheep and Bear Hug on the left, Moon Rabbits in the middle), the pouring of the molten bronze, the shells filled with molten bronze, the cooling of the shelled castings, a view of showing some of the rough castings, and finally, these sculpture after the metal spurs were cut off and separate pieces were welded together (two of each).
The final stage of the process is to refine the metal castings, sandblast them to clean them, and the application of patina, all of which is done at Zimmerman Fine Art Studio. Welds and imperfections are sanded, and details carved back where they are needed using pneumatic tools. Then each piece is cleaned by sandblasting so that a patina can be applied. A patina is created by adding chemicals or paint to the surface of the bronze to color and seal it. If this is not done, the bronze will react to its environment and usually turns a greenish grey color. While there are numerous patinas that can be applied, Zimmerman prefers to keep it simple, either black or white, so the beauty of the forms stand out.
Once the casting is finished, Zimmerman constructs simple shapes or more complex elements to go along with the cast sculpture at Zimmerman Fine Art Studio in Willington, Connecticut. Her preferred material for these elements is wood because she thinks it has a visual softness that works well with bronze. Also, since her father was a carpenter, she feels a connection with this material and likes working with it. That being said, in life-sized outdoor sculpture; stone, water or cement may be used along with the casting to endure they stand up to whatever nature has in store for them.
Zimmerman Fine Art Studio