A special clay body made of white stoneware with up to forty percent grog is used for raku. This enables the pieces to successfully withstand the rapid and drastic changes in temperature. The pieces are bisque fired normally, then glazed with a low fire glaze. Oxides can be added at this point. When the glazed pieces are completely dry, they are placed in the kiln. The temperature is raised quickly to approximately eighteen hundred degrees Fahrenheit. The glaze firing is observed from time to time as the glaze begins to melt, bubble and blister, then settles into a rough coat resembling an orange peel. Finally, it becomes a smooth honey finish which literally glistens. The pieces are then removed from the red, hot kiln, with special long handled raku tongs. At this point the glaze is still molten. The pieces are carefully placed into a pit or container in which sawdust, straw, pine needles of newspaper has been placed and it is lightly covered with the same material. A lid or cover is quickly clamped on the container or over the pit. Once the pieces have cooled, they are removed and the results are admired. Each piece must be carefully scrubbed to reveal its true beauty. The unpredictable results can be partially controlled by choice of glaze, oxides, timing, or even the combustible material. These variables all contribute to the exhilarating effects and excitement of raku.
Raku is closely tied to the Japanese Tea Ceremony and Zen Buddhism. Early oriental craftsmen made small
ceremonial tea bowls. We are using firing techniques that are essentially unchanged to this day. In essence we are dealing with earth, fire, air and water.
EARTH: The clay with which the pieces are made.
FIRE: Wood, coal or gas used in firing the pieces which usually occurs in an outdoor, homemade kiln.
AIR: The presence of air in the combustion and the
absence of air in the reduction pit: The glaze is molten
when the pieces are taken from the kiln and placed into a
pit of combustible material and the oxygen is cut off. The
burning material needs oxygen to continue burning.
Therefore, oxygen is stolen from the clay and the glaze
causing reduction and the wonderfully unpredictable effects.
WATER: The still warm pieces are taken from the pit and
are scrubbed to expose their beauty.