Raku is a type of 16th century Japanese pottery firing technique in which pieces are fired at low temperatures (up to approximately 1850 degrees) and taken out of the kiln when glowing hot.  They are then allowed to cool in the open air.  Traditionally, bowls made for the Japanese tea ceremony were glazed and fired using this method.

However, in the 1960s, the raku technique was westernized to include a reduction atmosphere for the pottery by use of combustible materials of various types (e.g., straw, shredded paper, sawdust), in order to produce carbon-trapping upon the exposed clay body.

The amount of time to glaze fire raku pieces is short (approximately one to two hours) as opposed to electric kiln firing times (which can be up to 16 hours).  Therefore, all materials need to be quickly accessible when the hot piece is pulled from the kiln, and then transferred to the combustion chamber for reduction.  After reduction has occurred, the pots are removed from the chamber and wiped or washed clean.

Another option for decorating the surface of the pot is to use horsehair instead of glaze.    With this process, a smooth, bisque fired piece is put into the raku kiln and fired until it reaches about 1250-1400 degrees.  The pot is then taken from the hot kiln and set on a fireproof surface and immediately decorated with horsehair, which leaves a wavy, hairy impression with a trace of carbon flashing on the piece.  When cool, the piece is gently wiped with a soft cloth or brush to remove any remaining bits of hair.  The final outcome of this technique creates a striking visual contrast upon the pot as a result of the horsehair application.

Raku pottery is not food safe or water tight due to the type of firing technique.