tatara

Tatara is a traditional Japanese furnace used to smelt iron from iron sand and charcoal to produce tamahagane, a high-quality steel historically used for traditional swordmaking and tools. The term refers to the kiln or furnace itself, and the method is one of the oldest iron-smelting techniques in Japan.

A tatara is a clay-lined pit furnace, usually several meters long and partly built into the ground. It is loaded with alternating layers of iron sand, charcoal, and clay, and air is supplied by bellows to reach high temperatures. The smelting lasts several days, during which time the iron melts and separates from slag. The resulting bloom is refined into tamahagane steel, whose carbon content varies by layer and is selected by swordsmiths for blade forging.

Production began in early Japan, with records dating to the Kofun period, and it peaked during the Sengoku era before continuing in some areas until the Meiji Restoration. The technique is closely associated with the crafting of traditional Japanese swords, especially the katana, and remains an important cultural symbol. Modern efforts preserve the process at a few traditional sites and museums where tamahagane is produced for contemporary swordmaking.

Today, tatara remains largely a historical or artisanal practice rather than a mass-production method. Some communities operate small-scale tatara for specialty tamahagane, and several sites are protected as industrial heritage.