During a trip to China, Tenmo co-founder Yongyun stumbled across an unusual mug tucked away in a small, unnoticed teahouse in the Fujian region. His astonishment was not only due to the cup's dark color, which already seemed unusual, but the most surprising aspect of this marvel was its incredibly random patterns and exceptional brilliance. After a long search, his meeting with the craftsman who produced this work opened his horizons to Tenmoku art.
Tenmoku takes its name from the temple on Tianmu Mountain (天目Mandarin: tiān mù; Japanese: ten moku; English: Heaven's Eye ) in China, where enameled iron bowls were used for tea. The style became very popular during the Song dynasty (960-1279). In Chinese, it's called Jian Zhan (建盏), which means "Jian (tea) cup".
Tenmoku "Chawan" teacup with bird spots, Li Da
According to chronicles in 1406, emperor Yongle (1360-1424) of the Ming dynasty sent ten ware Jian bowls to shōgun Ashikaga Yoshimitsu (1358-1408), who ruled during the Muromachi period . A number of Japanese monks who visited monasteries in China also brought pieces back home. As they became popular for tea ceremonies, more and more pieces were imported from China, where they became highly prized commodities. Three of these vessels from the Southern Song dynasty are so highly prized that they have been listed by the government as one of Japan's national treasures.
A longer cooling time produces maximum surface crystals. Potters can "fire" a kiln to achieve this effect. During a normal firing, the kiln is slowly brought up to maximum temperature by adding fuel, then refueling is stopped and the kiln is allowed to cool slowly by losing heat to the surrounding air. To extinguish a kiln, the potter continues to add a limited amount of fuel after the maximum temperature is reached to slow down the cooling process and keep the glazes molten for as long as possible.