What is a “Tsuchigama”?
Tsuchigama, coined by Tadashi Hirakawa is a type of pottery kiln, commonly built approximately during Kamakura( AD 1192-1334) and Nanboku （Southern and Northern Courts AD 1335- 1392) period by artisans in Bizen region, Japan. It is often called Bizen Koyoh or simply old kiln. In later years till recent days typical kilns are Noborigama (climbing kiln) or Anagama (kiln dug out on hillside).
For the last 25 years Hirakawa’s study and experiments have been focused on the characteristics of inner wall of Tsuchigama, believed to be the kilns of the middle age periods. The wall is considerably different from those with sun baked fire resistance bricks popular in later years, and rather it is made with soft natural earth without hardening by pounding. Hirakawa came to a conclusion that this approach in building kilns enables a unique convection and heat transfer, which once helped create the traditional Bizen texture.
Thus he calls this type of Anagama kiln using common earth and without chimney, a Tsuchigama. Tsuchigama also uses all easily available natural material from surrounding areas and thus turns the process of building kilns through final pottery making the most environment friendly.