The lost-wax casting process may also be used in the production of cast glass sculptures. The original sculpture is made from wax. The sculpture is then covered with mold material (e.g., plaster), except for the bottom of the mold which must remain open. When the mold has hardened, the encased sculpture is removed by applying heat to the bottom of the mold. This melts out the wax (the wax is lost) and destroys the original sculpture. The mold is then placed in a kiln upside down with a funnel-like cup on top that holds small chunks of glass. When the kiln is brought up to temperature (1450-1530 degrees Fahrenheit), the glass chunks melt and flow down into the mold. Annealing time is usually 3–5 days, and total kiln time is 5 or more days. After the mold is removed from the kiln, the mold material is removed to reveal the sculpture inside.