Warm glass

Warm glass or kiln-formed glass is the working of glass, usually for artistic purposes, by heating it in a kiln. The processes used depend on the temperature reached and range from fusing and slumping to casting. Warm glass or kiln-formed glass is the working of glass, usually for artistic purposes, by heating it in a kiln. The processes used depend on the temperature reached and range from fusing and slumping to casting. 'Warm glass' is in contrast to the many cold-working glass processes, such as leaded glass. 'Hot glass', glassblowing, or lampworking is the working of glass in a direct flame, such as for laboratory glassware and beadmaking. Warm glass working uses a variety of processes, according to the working temperature and the time the glass spends at this temperature. The glass becomes progressively softer, less rigid, and less viscous with increasing temperature. Kiln-worked glass (unlike lamp working) responds slowly though, and so the amount by which this affects the glass depends on the time it spends at working temperature.