Finely-ground borosilicate glass (coloured by trace metallic compounds) which melts at 800 to 820 °C is fused to the surface of certain metals. Kilns may be either electric or gas fired but some work can be done with a gas torch.
Firing ceramic materials in ad hoc outdoor kilns, including raku kilns, portable kilns and brick-built kilns. Kilns may be electric or use solid fuel, oil or gas.