Types of Raku
The Japanese potter ended his raku process when he removed the pot from the kiln, allowing the glaze to crackle by cooling in the air, thus separating the glaze slightly from the clay body; or, if wanting to emphasize the crackle, by plunging the pot into a tea bath.
American Style Raku
Americans added one step to the raku process by including a post firing reduction which first places the hot pot in contact with various combustibles and then covers the pot to close off the air supply. This technique results in pots that look more smokey than Japanese pots. Most potters consider Paul Soldner the father of American raku who developed the technique after misinterpreting his reading of Bernard Leach's description of the process. Solder, according to potter, Tim Andrews, during a pottery entertainment at an arts festival in Claremont, California, "delighted the audience as hot, glowing pots were pulled out of the kiln and the potter ran through the crowd finally dunking the ware into a fish pond." When the pots shattered, he on a 'serendipitous hunch' placed the next batch of pots into some leaves prior to cooling, resulting in some soft coloring effects, thus was the birth of American reduction raku (19-20).
Slip Raku
Gerry Caplan experimented further with the reduction process. Using underglazes to make his drawings prior to the bisque firing, Caplan later covered the entire bisqued pot with slip and then with a pointed instrument drew through the slip in places where he wanted smoky carbonization effects. His technique is sometimes called smokeless raku since he minimizes the combustibles, using only one sheet of newspaper under and over the pot when it is removed from the raku kiln. After the smoking, Caplan lifts off the slip which does not adhere to the pot, thus revealing the carbon lines he created with a needle.
Naked Raku
Kate and Will Jacobson carried Caplan's slip technique one step further. After the slip has been applied to the bisqued pot and allowed to dry, they add a raku glaze. The glaze fuses to the slip during firing and peels off of the pot when cooled to reveal interesting shadow lines. By adding several layers of glaze and going through several firings, the Jacobsons have been able to achieve a "batik effect." They draw intricate figures through the glaze to achieve a reverse image with carbon saturation (qtd. in Von Dassow 137).
Traditional Japanese
Western Raku
Paul Soldner
Slip Raku
Gerry Caplan
Naked Raku
Kate & Will Jacobson