The Bronze Age dates to 3000 BC, when someone had the idea to make an artifact with bees wax and cover it with liquid clay. Once fired, the clay hardened and the wax melted away, leaving an empty space. Copper and tin were mixed and melted together at about 2200° F then poured into the cavity. Once cooled, the clay was knocked off and the first bronze artifact was cast.
How to Create Bronze Art
1. Sculpting in Clay
As a self taught sculptor, I sculpt using aluminum foil-- it gives me all the flexibility that I want and enables me to manipulate the aluminum foil structure until I am pleased with the form. Then I apply clay, which I soften by placing in a microwave. With a spatula, I smear the clay on to the aluminum form. Finally, I apply detail with my fingers being my main tools and using wood fragments' rough edges to give texture.
2. Mold Making
The complexity of the sculpture determines the amount of molds needed. Silicon rubber is used to cover the clay sculpture, then a second mold using plaster or fiber glass is made on top of the silicon to give it rigidity. When the molds are ready, the original sculpture is removed, and the mold is used to make a wax copy which will be sent to the foundry.
3. Foundry Casting
During the ceramic shell process, the wax copy is submerged in a slurry bath made of silica flour and a liquid binder. Once removed and completely dried, the process is repeated until the ceramic is about ½" thick around the wax.
Then the ceramic is placed in an oven for the dewaxing process which leaves an empty space. Melted silicon bronze fills this empty space. When the bronze cools, the ceramic is knocked off, and the bronze casting is exposed.