The artist carves the wax into the desired shape. Wax will carry the smallest of details, and, unlike less forgiving stone or wood, wax can be smoothed out or easily rebuilt to correct errors. Wet plaster is poured over the finished wax object. When the plaster dries, molten metal is poured into the form through an opening. The wax melts away through another opening, but the sculpture's image, preserved in the plaster, is transferred to the metal casting.
Let's say the artist is a bit more commerce-minded, or has many customers for his "unique" works. The artist encases the wax sculpture in liquid rubber. When the rubber dries, the artist carefully cuts the rubber away. Now the artist puts the rubber halves together and injects molten wax. When the wax cools, the artist has a second wax sculpture. The artist can make numerous wax copies this way, then turn each replica into an identical lost-wax masterpiece.
Technology eases the process, a big help when the artist is creating small-scale sculptures -- better known as jewelry. The delicate lines of the wax jewelry model are carved with dental tools. This seems appropriate, since the lost-wax process is also used to make false teeth. The wax sculpture is placed in a container flask before the plaster or other covering material is poured. While the plaster is still wet, the whole thing is placed in a vacuum chamber to remove any air bubbles. Finally, metal is machine-injected, not just poured, to ensure a more consistent finish.
What if the artist has big ambitions but a small workshop? Or prefers to work in wood, clay or metal but wants to make metal copies? Once the sculpture is created, flexible rubber is painted onto the sculpture. A plaster or resin shell is built around the sculpture to hold the rubber in place. When the rubber dries, it is removed from the sculpture. Once again the rubber mold is filled with wax, and the lost-wax process begins anew. Separate rubber molds can be made of different parts of large sculptures. Once the parts are cast using the lost-wax process, the metal parts are welded together.