The Technique of Mike Curtis

Fine art casting process

Mike Curtis Limited Edition Bronze Sculptures are created by the sculptor in his North Idaho studio. Each is comprised of the highest quality bronze found anywhere in the world. Mike Curtis sculptures are cast utilizing the ancient lost-wax method, the premier method of fine art bronze casting, and he is “hands-on” throughout the entire process from start to finish. The following information will help you to understand the many steps, requiring several months, which comprise this laborious and intensive process. The result is a magnificent work of art, created and cast in the United States, by the leading sculptor of the bald eagle as well as many other fascinating wildlife subjects.

Mike Curtis first sculpts the original in clay or wax. Upon completion of the original sculpture, a pliable silicone rubber mold is carefully applied. This mold captures every detail put into the original work, and is one of the most critical phases in the bronze process. The mold is used to create an exact duplicate of the original design.

When the desired thickness is achieved on the rubber mold, a plaster shell is then applied over it. This plaster shell will retain the shape of the rubber mold when the mold is removed from the clay. Once removed, the rubber molds are used to form a wax duplicate of each section by pouring hot wax into the rubber mold to produce an exact replica of the original. When cool, the wax castings are carefully removed from the molds.

Several hours are spent working by hand with the wax to reproduce all of the detail of the original. The wax casting is gated with wax tube-like fixtures, called sprues, to allow even flow of molten metal and to alleviate the trapping of air and gas. A sprue cup is placed onto the sprues to receive the molten bronze. The wax casting is then dipped repeatedly over a period of a week in liquid ceramic slurry. Several layers of fine, medium, and coarse silica sand are applied, creating a stable ceramic shell, which is allowed to cure for several days. This process creates a ceramic shell around the wax reproduction of the original.

Once completely dry, the piece, now coated in a ceramic shell is fired in a burnout kiln. This bakes the ceramic shell and eliminates the wax, which escapes through the hollow tubes created by the sprues, leaving a cavity in its place. (Thus the term "Lost-Wax"). The ceramic shells are removed from the kiln and propped into position for pouring. Ingots of bronze are heated until they turn molten. The molten bronze, at a temperature of 2100 degrees Fahrenheit, is poured into the hollow ceramic shell, filling the space that was left when the wax was lost. The tubes now work to evenly distribute the bronze to all areas of the shell. The sculpture is left to cool. After cooling for several hours, the ceramic shell is carefully broken away, revealing the bronze sculpture within. A cutting torch is used to remove the sprues.

Fine sand particles are blasted under air pressure to remove the last traces of ceramic shell that adheres to the bronze. Many weeks of grinding, chasing (tooling), welding, sanding and polishing are performed to insure the sensitivity and exact detail of each work of art.

The final stage in the completion of the bronze is the application of the color patina finish, with chemicals and heat, to create the desired effect. Much like a fine painting, the application of the patina is a unique work of art in itself.

When all of the finish tooling, patina, and precious metal finishes (such as gold and silver) have been applied, the sculpture is mounted on a granite and/or wood base which is designed specifically for each work of art.

For orders or additional information, you are welcome to e-mail Mike Curtis at:


To order a Mike Curtis sculpture

call: 208-263-8074

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Mike Curtis

Fine art casting

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