Ushikubi Sue Ware Kiln Ruins: Umegashira Kiln
[表のキャプション]
Techniques for firing the extremely hard, ash-colored pottery known as Sue ware were brought from the Korean Peninsula in the fifth century. Production at Ushikubi began in the sixth century, and it became Kyushu’s largest Sue-ware production site. One of the kilns has been preserved in situ to illustrate the process.
[裏の解説]
The ruins of over 600 ancient kilns have been discovered in the cities of Ōnojō, Kasuga, and Dazaifu, evidence of a once-thriving production center for Sue ware. Sue ware is a type of stoneware pottery introduced from Korea in the early fifth century. Production at the Ushikubi site was underway during the sixth century, and it expanded further in the eighth century as Dazaifu grew into a major city. To make Sue ware, craftsmen shaped clay on a potter’s wheel, then fired it at high temperatures to create durable, unglazed vessels with a characteristic bluish-gray color. The Ushikubi kilns produced a variety of pieces, including ritual vessels, tableware, and roof tiles.
The kilns were earthen tunnels—some as long as 11 meters—constructed in a slope. The unfired pottery was arranged inside on stones or depressions scraped into the earth’s surface. Below them, at the base of the slope, wood was piled inside the tunnel entrance. A fire was lit, and the burning wood produced intense heat and smoke that rose up through the tunnel, firing the pottery. At the top, one to six vents could be opened or closed to release smoke and regulate the heat. Once the kiln reached an appropriate temperature, its entrance was sealed. Temperatures inside the kilns could exceed 1,000 degrees Celsius, hot enough to maintain combustion even in the absence of oxygen. It was this oxygen-free environment that produced Sue ware’s characteristic gray color. (Pieces fired in the presence of oxygen turn red.)
Firing Sue ware consumed a large amount of wood, so artisans used a kiln only until they had exhausted all of the fuel in the area. Consequently, kilns were built farther and farther uphill in pursuit of lumber from the still-forested mountains. After a kiln fell out of use, it was usually abandoned as-is. Occasionally, however, it became the grave of the craftsman who had used it. In such cases, the artisans were buried inside the earthen tunnels with their personal belongings, which included iron swords and knives, arrowheads, ear adornments, and jars of red pigment.
One of the Ushikubi kilns, called the Umegashira Kiln Ruin, has been preserved largely intact and is open to visitors.