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Bronze Casting

Rodin worked in traditional sculptural materials such as clay, wax, plaster, bronze, and marble. Although he did not attend the renowned École des Beaux-Arts (School of Fine Arts) in Paris, he learned the craft of sculpture through experience and years of employment in the studios of other artists. As he explained, "In addition to sculpture and design, I myself have worked at all sorts of things. I've cut down marbles, and pointed them; I've done etching, and lithography, bronze founding and patina; I've worked in stone, made ornaments, pottery, jewelry—perhaps even too long; but it all has served. It's the material itself that interested me. In short, I began as an artisan, to become an artist. That's the good, the only, method." Once he became an established artist, Rodin relied on a large studio of assistants to help him create large-scale works. Their presence allowed him to delegate the production aspects of his sculptures so that he could focus on conceiving and executing new pieces.

Like other sculptors of his era, Rodin hoped to make as many versions of his works as possible in order to maintain his reputation and allow him to recoup the high costs of sculpture production. Each version is considered original as long as it was produced under the supervision of the artist or his estate, now overseen by the Musée Rodin in Paris. Most of the sculptures in the collection of the Rodin Museum were cast between 1924 and 1926, under the supervision of the Musée Rodin and by craftsmen who worked with Rodin during his lifetime, making them both original and high-quality works of art.

Image Essay

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Step 1

The process of sand casting begins with an original sculpture by the artist, formed in clay, wax, or plaster. From this original, a plaster model is produced by means of small, sectional molds, also called piece molds. The model is thoroughly dried and coated (shellac was commonly used in Rodin's studio). The coated plaster surface is then dusted with a separator, such as talc, so that it will not stick to the fine molding sand that will be packed around it.

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Step 2

In the case of small sculptures, the model is half-buried in a leveled bed of sand held in a rigid frame; the sand bed is also dusted with a separator. (Larger sculptures are often cast in sections and require more complex molding arrangements.)

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Step 3

The exposed top half of the sculpture is covered with a layer of fine molding sand usually mixed with clay. Coarser sand is added around and over the fine molding sand, supported in a second frame, and firmly packed. The two frames are turned over and the process repeated for the other side of the model.

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Step 4

The model is removed from the packed sand in each frame, without disturbing the sand. When the two frames are put back together, there is a large void where the model had been. In order to make the bronze cast hollow for weight and other considerations, the void within the mold must be filled with a core.

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Step 5

Typically made of plaster, sand, and organic material supported by an iron framework, the core is uniformly smaller than the sand mold by about 3/8–1/4 inch. Pins or rods (chaplets) inserted into the core hold it in a fixed position in the mold when the molten metal is poured.

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Step 6

The sand surrounding the core is pierced to create channels. Some channels, called gates and runners, allow hot metal to enter the empty space; others, called vents, permit gas to escape during the process.

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Step 7

Bronze is melted in a crucible and poured into the mold through cups or funnels called sprues. The molten metal fills the space between the core and the sand. After the bronze has solidified in the mold, the molding sand can be knocked away and the core removed mechanically.

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Step 8

At this stage, the surface of the sculpture retains bronze that has formed from gates, vents, or cracks in the sand mold. These are removed by grinding, sawing, or filing.

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Step 9

The metal surfaces of the cast are repaired wherever there are flaws, usually by setting in patches or plugs. Other adjustments to the surface appearance are made through procedures known as chasing and finishing, which often include hammering, texturing, abrading, and buffing. Finally, the bronze is coated with chemicals that cause the metal to change color. This last process is called patination. Rodin provided the foundry with specific patination instructions for his works, and inspected the finished sculptures to be sure they met his exacting standards.