Kilns; intermittent kilns are thermally insulated chambers or ovens made to produce and control temperatures in which different ceramic materials are fired. When functioning, they are shut so the internal temperature increases according to a schedule and when the process of firing has finished they are left to cool.
There are many types with different methods used for firing different materials; drying grains and wood; baking batter which turns into bread; firing clay into bisque which is hard, breakable but still porous; and vitrifying glazes into a layer of glass which stops the bisque being porous and makes the decoration permanent, giving depth and shine to the surface. A studio kiln is designed so heat can generate from 0º C up to 1350º C and an industrial one can reach much higher temperatures.
Kiln have changed in the last years before the heat was controlled by cones and now they are completely automatic. For information on cones Read more about: Cone – Pyrometric / Cone – Sockets / Cone – Witness