Raku is a form of Japanese pottery characterized by low firing temperatures (resulting in a fairly porous body), 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. Raku is considered the traditional method for creating bowls for the Japanese tea ceremony. Raku tea bowls are hand-made from earthenware, each with a unique shape and style. Raku techniques have been adopted and modified by contemporary potters worldwide.

The use of a reduction chamber at the end of the raku firing was introduced by the American potter Paul Soldner in the 1960s to compensate for the difference in atmosphere between wood-fired Japanese raku kilns and gas-fired American kilns. Typically, pieces are removed from the hot kiln and 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.

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.

The glaze firing times for raku ware are short: an hour or two as opposed to up to 16 hours for high-temperature cone 10 stoneware firings. This is due to several factors: raku glazes mature at a much lower temperatures (under 980°C/1800°F, as opposed to almost 1260°C/2300°F for high-fire stoneware), kiln temperatures can be raised rapidly, and the kiln is loaded and unloaded while hot and can be kept hot between firings.

Because temperature changes are rapid during the raku process, clay bodies used for raku ware must be able to cope with significant thermal stress. The usual way to deal with this is to incorporate a high percentage of quartz, grog, or kyanite into the body before the pot is formed. Each is used to add strength to the clay body and to reduce thermal expansion. Although any clay body can be used, most porcelains and white stoneware clay bodies are unsuitable for the western raku process unless some material is added to deal with thermal shock. Aesthetic considerations include clay color and fired surface texture, as well as the clay's chemical interaction with raku glazes.

Western raku is typically made from a stoneware clay body and are bisque fired at 900°C (1650°F) and glaze fired (the final firing) between 800-1000°C (1450-1800°F), which falls into the cone 06 firing temperature range.

The process is known for its unpredictability, particularly when reduction is forced, and pieces may crack or even explode due to thermal shock. Pots may be returned to the kiln to re-oxidize if firing results do not meet the potter's expectations, although each successive firing has a high chance of weakening the overall structural integrity of the pot. Pots that are exposed to thermal shock multiple times can break apart in the kiln, as they are removed from the kiln, or when they are in the reduction chamber.