Slumping is a categorical description of an area of techniques for the forming of glass through the use of heating glass to the point where it becomes plastic. It is generally formed by the force of gravity. Glass is most commonly heated in an oven, often using glass in a sheet form and 'slumping 'it over a form or into a mold. Molds are generally made of high temperature plaster, clay coated with plaster or another release agent, graphite, sand mixed with a bonding agent, or etc. At the point where the glass has achieved the desired form the heat is quickly vented and the temperature reduced to prevent further movement of the glass and then it is stabilized at its respective annealing temperature and annealed.