Case Study of Lost Wax Casting for Bronze Sculpture

Lost wax technique is one of the most used methods to cast metal sculpture. It has a very long history. This technique can be defined as a process by which a metal (such as silver, gold, brass or bronze) sculpture is cast from an artist’s sculpture as a wax mould.

Here is a case of a sculptures made from lost wax technique in ancient China to show how far lost wax technique can go. This piece is called Zeng Houyi Bowl for holding liquor. The original piece was made around 500 B.C. It was owned by a local king of Ancient China.

The most visible character of this piece is its extremely complicated patterns. These are 102 dragons pattern on this 16.5 inch tall works. Considering the time (500 B.C), it’s very unbelievable our ancestors were capable to use lost wax so well. The picture shown is our replica and to be honest, our works is still not as intricate as the original piece.

No matter how complicated the sculpture is, there are two basic methods to make wax mould.

Direct way: sculptor carves on a wax block directly to make the desired shape. This is a onetime mould because it can only be used once.

Indirect way: the wax mold is made from a negative silicone rubber mold which is made from a sculptor’s original piece (clay, plaster, resin etc)

The quality of wax work affects the final bronze directly so a wax mold needs a little bit refining after coming out. The thickness of the bronze is controlled by the thickness of wax work so it’s important to keep wax thickness consistent. Inconsistency of wax work may lead to fault or imperfection on the casting duo to the different shrinkage rate of different parts. Though rarely used in large scale sculpture, lost wax is warmly welcome because it’s very suitable for small and intricate piece such as life size figure, bust, etc.

The wax used for making the mold varies and I plan to write another post on this topic.

Below is a simple demonstration on how a resin master pattern become into a bronze bust.

I’ll write a series articles about how to apply lost wax technique to create wonderful bronze sculptures and please let me know if you have any question. Any comment is highly appreciated.

( by Owen Weng)