There have been some questions concerning the difference between bonded bronze (cold-cast bronze), and bronze (hot-cast bronze). Understand that in either of the above materials, the casts (the product made out of the mold) are made using the same rubber mold; which is taken from the original clay sculpture. So that the sculpture is exactly the same, but made in a different material.
Cold-Cast Bronze or Bonded Bronze as it is sometimes called, is actually made of a polyester, epoxy or another resin. Bronze powder and paints are used to achieve the bronze appearance. Marble dust can also be added to the resin to achieve a marble look, hence bonded stone.
Hot-Cast Bronze is actually Bronze - essentially copper and tin; the tin not exceeding 11%. Other metals may be added to give different characteristics to the metal.
The making of a Hot-Cast Bronze is a complex and time consuming process, and specific technical expertise is needed to accomplish the task of making a bronze. The most known and used process for making sculpture is called the "Lost Wax" Process:
A 1/4 inch hollow wax of the sculpture is made from the rubber mold capturing all the details . The wax is layered inside and outside with seven coats of a ceramic shell material; which harden around the hollow wax sculpture. The ceramic shell is then placed into an oven and the wax sculpture is melted out. This leaves a 1/4" space once occupied by the wax. Molten bronze is then poured into this space in the ceramic shell, and is set aside to cool and harden. The ceramic shell is broken off the bronze and the finishing process begins; cleaning and chaising the bronze sculpture. The finished bronze is then ready for patination. A torch is used to heat up the surface of the sculpture, chemicals deluted in water are brushed onto the heated surface creating a wide range of colors and patterns. This is just a brief explaination of the process and to really appreciate the process, one should visit your local sculpture foundry.
After comprehending the processes above, one can understand why the cost for a bronze statue is much greater than that of a cold-cast bronze. In most cases, the sculptor creates smaller editions (number of sculptures made from the mold) of Hot-Cast Bronze than those cast into Cold-Cast Bronze. In general, the cost of a bronze sculpture will increase as the edition is bought up. Someone purchasing sculpture 1/9 will pay significantly less than someone purchasing 9/9. It is also the most durable and lasts the test of time. Other metals generally used for sculpture: Stainless Steel, Aluminium, Silver.
Cold-Cast or Bonded Bronze can also be collectable and allows a wider range of clients. It is also very durable, and larger sculptures (Tiger Stadium) can be created at a fraction of the cost if bronze is out of the question. |