Bronze Sculptures

Written by Patty Yu
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Sculpting is an art form where figures are shaped with a material such as clay or cast with metal such as bronze. Many other materials can also be sculpted, including stone and wood. Since these materials have such unique compositions, artists must integrate different methods for sculpting each material. The varying compositions also make certain materials more durable than others.

Bronze Sculptures

Unlike stone sculpting, bronze sculpting is completed using a casting method. Copper is the main component and is melted down and mixed with about five percent silicon. This bronze alloy has a quality that is highly desirable, where the metal expands just slightly upon setting. As it expands, every last line and crack in the mold fills for a finely detailed piece of bronze art.

However, bronze casting requires many weeks or even months to complete. Several steps are necessary before even creating the last mold used to hold the molten bronze. To explain casting simply, the artist creates a model, then a mold, then another model, another mold, and finally the bronze sculpture. However, each model and mold also requires several small steps.

Steps for Making Bronze Sculptures

The first step in bronze casting is sculpting the subject out of clay. This clay model must accurately represent the final product exactly in size and detail. However, some bronze sculptures have multiple pieces, so separate sculptures might be made and welded together later. The clay model is then used to make a rubber mold layered with plaster for rigidity.

Another wax model is made out of the rubber mold and "chased" by the artist. Chasing is a process where the artist fixes any imperfections such as bubbling and raised seams. Once chased, the wax model is used to make a hard shell. It is dipped into a ceramic mixture several times and then fired in a kiln at at least 2,000° F. This shell is the final mold.

When the ceramic mold is fired in the kiln, all the wax melts away, which is why this casting method is called "lost wax casting." The artist now has a strong ceramic shell that can hold molten bronze. The inside of the shell represents every detail in the final sculpture. As the molten bronze cools, the details are filled and a beautiful bronze statue results. There is a second chasing process completed on the bronze piece and then additional pieces may be welded together. Bronze sculptures are almost impossible to destroy unless melted down again.

Sculpting with Stone

There are many different stones used for sculpting, each with unique properties that require the use of different tools. Some commonly used stones for sculpting are limestone, marble, and granite. Limestone is a medium-soft stone, which means it is very easy to work with using all kinds of sculpting tools. However, limestone cannot be polished for a smooth, shiny finish.

Marble is a medium-hard stone, making it more challenging to sculpt than limestone. However, the level of hardness and fine grain of marble makes it excellent for carving fine details into the surface. You cannot do this with limestone because the stone's granular texture does not allow it. Also, marble can be polished into a beautiful, glossy finish that is very aesthetically appealing.

The most challenging stone to work with is granite, being the hardest stone. Hard stones like granite are extremely durable, but impossible to carve. It is, however, possible to cut with certain tools and saws. You will commonly find granite fountains, benches, walls, and monuments with smoother surfaces and simpler lines. Granite sculptures are still not as durable as bronze sculptures

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