Lost Wax Bronze Casting Process

Lost Wax Bronze Casting Process

Bronze sculpture is one of the most enduring and revered of all art forms.lost wax bronze casting process The lost wax casting process used to create it dates back thousands of years. A bronze sculpture is created by building a mold around a sacrificial wax model, which when melted away creates a space to flow in the liquid metal of bronze. This enables the creation of detailed, highly accurate metal objects that can’t be achieved by direct carving into stone or wood, or with sand casting.

The sculptor first sculpts the object to be cast in clay, creating a negative impression of the sculpture that will be cast.lost wax bronze casting process A second clay model is then pressed into the negative, creating a sharply defined duplicate of the original. This is called “making a mold.”

A second, rock-hard material that is resistant to high temperatures is then placed over the clay models and pressed into place. This is the "investment." For most of history, this was made from plaster and sand, but now ceramic shell has replaced these materials for greater durability. A gap exists between the model and the investment because a rock-hard shell has been built around it.

Now that a gap has been formed between the original clay models and the investment, the wax model is removed from the gaps and carefully coated with a layer of finely granulated silica slurry, which is referred to as “shelling.” This is repeated several times to build up a shell half an inch thick around the original clay sculpture.

When the ceramic shell has cooled, it is chipped away, exposing the wax model and a space to pour in the molten bronze. The wax model is then called a "positive." The sprueing, or gating, of the wax copy begins at this point. A treelike structure of wax channels, which will later provide paths for molten metal to travel to the sculpture, are added to the positive.

The sprued wax copy is then covered in a refractory material that is comprised of a mix of silica and ceramic, which are resistant to high temperatures, and placed into an oven for one to two weeks. During this time, the wax melts and flows out through the sprued channels, leaving a negative space that will be filled with molten bronze.

The sprued positive is then chiseled or sand-blasted, and the wax is melted away, revealing the finished bronze sculpture. The sculpture is then buffed and polished to remove pits from air bubbles, stubs left by the sprueing, and to smooth any unevenness of the surface. The finishing process can take several hours to complete. The result is a spectacular, one-of-a-kind bronze object. The sculptor can now begin to envision the next piece to be cast in bronze. The possibilities are endless.

Tags:lost wax casting molds | lost wax casting service | pump casting