Tenmoku is the Japanese word for a type of tea bowl first produced in China during the Song Dynasty (960-1279). It also refers to a mountain between China's Zhejiang and Anhui Provinces (Mt. Tienmu in Chinese, Mt. Tenmoku in Japanese).
The original name for these wares in Chinese was jianzhan. The first mention of tenmoku in a Japanese document occurs in 1335 in a record by Onkei Soyu, a monk who studied at Mt. Tienmu. In the 13th century, Tenmoku wares made at kilns in Fujian Province were brought back to Japan by Japanese Buddhist monks. The Ashikaga shoguns (Japanese family that occupied the office of shogun from 1338 to 1568) held tenmoku and seiji (celadon) in the greatest esteem and this reverence reached its peak during the reign of the shogun Ashikaga Yoshimasa (1369-1395), the eighth shogun.
From that time in history, only four "yohen" tenmoku tea bowls have survived. Yohen refers to a natural ash glaze; the term literally means "changed by the fire/flame." All four are in Japan and three are designated as national treasures. These three are, respectively, in the Seikadou Bunko Art Museum, the Fujita Art Museum, and the Ryuukouin Subtemple of Daitokuji Temple.
There are a few kinds of tenmoku. Here are two of the most common.
- Yohen refers to changes that take place in the kiln, and it is also used for Bizen, where the glaze runs during firing. Sometimes this is called a "hares-fur" effect. Yohen also refers to the build-up of ash on the kiln floor and the natural glazing brought about by this ash.
- Yuteki is an oil spot effect that occurs when there is an overload of iron oxide which is allowed to cool slowly and forms effulgent spots on the surface. It is a very difficult technique.
Like Celadon, the Tenmoku style is very difficult to master, and the number of exceptional Tenmoku artists in Japan today is very small. One of the best is Kamada Koji. Both photos on this page are pieces by Kamada. Click below link for more on this artist.