Slumping
Slumping is the process of heating a flat sheet of glass in a kiln until it softens and sags into or over a mould. When it is cooled, the glass keeps the shape of the mould. Bowls, dishes, curved panels and plates are made in this way.
The temperature is lower than for full fusing, typically in the range of about 600 to 680°C, depending on the glass and the depth of the shape. The glass must be held there until it has sunk to the shape, and then it is annealed. The mould is coated with kiln wash, so the glass does not stick to it.
Slumping is part of kiln forming, and may be used on its own or combined with fusing, so that a fused flat piece is then shaped into a curve.