Raku is a form of Japanese pottery characterized by low firing temperatures (resulting in a fairly porous body), glazes, and the removal of pieces from the kiln while still glowing hot. In the traditional Japanese firing process, the pot is removed from the hot kiln and put directly into water or allowed to cool in the open air.

The process was adapted in the 1960s with the use of a reduction chamber at the end of the raku firing.  It was introduced by the American potter Paul Soldner to compensate for the difference in atmosphere between wood-fired Japanese raku kilns and gas-fired American kilns. Typically, pieces removed from the hot kiln are placed in masses of combustible material (e.g., straw, sawdust, or newspaper) to provide a reducing atmosphere for the glaze and to stain the exposed body surface with carbon.

Western raku potters rarely use lead as a glaze ingredient, due to its serious level of toxicity. Japanese potters substitute a non-lead frit. Although almost any low-fire glaze can be used, potters often use specially formulated glaze recipes that “crackle” or craze (present a cracked appearance), because the crazing lines take on a dark color from the carbon.