To begin, an armature is created which is the inner structure. This supports the clay that is used as a modeling medium. Armatures are usually made from wood and aluminum, however sometimes a sturdier metal is desired. If the piece is large, styrofoam fastened by wire can be incorporated in the armature to add bulk.
The piece is then sculpted out of oil-based plastilina clay around the armature. This part of the process is the most time consuming, as there is intricate detail inherent in each sculpture.
When the original modeling is completed, a "mother mold" is made. This rigorous process can often destroy the original, therefore extreme caution must be observed in its creation. The mother mold is similar to a three-dimensional puzzle with a hard exterior (plaster, fiberglass, etc.) and a flexible interior (a rubberized or latex material). Sometimes there are several sections of the mother mold for one sculpture, depending upon the complexity and size of the original sculpture.
Upon completion of the mother mold(s), hot wax is poured or brushed into the negative, thus the entire sculpture is created all over again out of wax. The wax pieces are joined together and re-worked until the wax sculpture looks exactly like the original clay sculpture. If it is a very large piece, the wax sculpture will be left in refined pieces and welded together later after the metal casting.
The completed wax is now ready for another mold or "investment" (made from plaster, sand and vermiculite) which is coated over the finished wax. When a hard investment shell covers the wax, the investment is heated and the wax is burned out. This leaves a negative, again, of the original sculpture. Into this negative, molten metal is poured.
After the metal is poured, the metal finishing work begins. This involves cutting, grinding and smoothing the casting.
The next step is the patina, or coloring, of the metal. This process involves heating the piece with a torch and spraying specific chemicals, based on the color desired. After the desired color is attained and while the metal is still hot, a coat of wax is applied to add luster and to protect the patina.
Usually the last and final step is attaching the sculpture to a base which involves drilling and bolting.
The entire process is called "Lost Wax Casting" and has changed very little since the Greeks first used it in antiquity, circa 500 B.C.