Fused glass is glass that has been fired (heat-processed) in a klin at a range of high temperatures from 593 °C (1,099 °F) to 816 °C (1,501 °F). There are three main distinctions for temperature application and the resulting effect on the glass.
Firing in the lower ranges of these temperatures 593–677 °C (1,099–1,251 °F) is called slumping. Firing in the middle ranges of these temperatures 677–732 °C (1,251–1,350 °F) is considered "tack fusing". Firing the glass at the higher part of this range 732–816 °C (1,350–1,501 °F) is commonly described as a "full fuse".
All of these techniques can be applied to one glass work in separate firings to add depth, relief and shape.