Tatara (furnace)

The tatara (鑪) is a traditional Japanese furnace used for smelting iron and steel. The word later also came to mean the entire building housing the furnace. The traditional steel in Japan comes from ironsand processed in a special way, called the tatara system.^[1]

Iron ore was used in the first steel manufacturing in Japan. Tatara steelmaking process using ironsand was conducted in the Kibi Province, which later became the base of the Bizen school of swordsmithing, around the middle of the sixth century, and steelmaking using ironsand is thought to have spread from Kibi to various places in Japan. In western Japan, a low box-shaped furnace different from the Chinese and Korean style was used to refine iron, and in eastern Japan, both a low box-shaped furnace and a vertical furnace unique to Japan were used.^[2][3][4][5]

In the Middle Ages, furnaces were enlarged to produce more steel of higher quality, and underground facilities were also huge and complicated to keep the furnace warm and reduce humidity. In addition, a new method of collecting ironsand, called kanna nagashi (鉄穴流), which can efficiently collect more ironsand using waterways, was adopted.^[2][3][4][5]

In the Edo period, tatara steelmaking was further improved and became the same as today's tatara steelmaking in Japan. Tatara steelmaking came to be carried out in a stereotyped building called takadono (高殿), and a space called Hondoko (本床), where charcoal is laid, and a space called Kobune (小舟), which has a tunnel-like gap, were installed under the steelmaking furnace, completing the underground structure known as Hondoko zuri (本床釣り). In the late 1600s, tatara steelmaking adopted a revolutionary invention. It is a foot-operated blower called a tembin fuigo (天秤鞴), which can blow a large amount of air into the furnace to increase the temperature. As a result, high quality steel can be produced in large quantities.^[2][3][4][5]

By 1920, Tatara Furnaces were no longer economically viable and they closed once the Western blast furnace was introduced to Japan. In 1977, the Society for Preservation of Japanese Art Swords and historical firearms (Nihon Bijutsu Token Hozon Kyokai) with the approval of the Japanese government's department of the environment built a tatara furnace to make Japanese swords.^[2][3][4][5]

Tamahagane (玉鋼) is a general term for steel, not used prior to the Meiji Era, literally meaning "precious steel". Steel is smelted at Shimane facility for Japanese swords (nihontō (日本刀), commonly known as katana (刀)) by contemporary Japanese forge masters like Kihara Akira and Gassan Sadatoshi is still smelted in a tatara. One of the few remaining tatara is the Nittoho tatara in Shimane Prefecture, Japan.