Unnan, Shimane Pref. – Inside a picket outbuilding within the distant hills of Yoshida, a part of Unnan, Shimane Prefecture, the air is thick with warmth and a tangible sense of anticipation. Women and men who’ve labored shoulder to shoulder for the previous 24 hours, including iron sand and charcoal and blowing air right into a clay furnace, watch because the partitions are rigorously damaged aside and out emerges a 1-meter-long, 120-kilogram glowing black mass.
That is kera, the bloom of crude iron created by the traditional tatara smelting course of. Hidden inside is tamahagane — the metal prized for hundreds of years by katana swordsmiths and different craftspeople.
Within the conventional tatara methodology, producing this kera takes subjective judgments primarily based on the colour of the furnace’s flames or the sound of the air speeding via it. For many of the 24 hours, no person is aware of if the result’s profitable till the furnace is opened up. And even after the tatara is deconstructed, the kera should cool naturally after which be damaged up and sorted into totally different grades, together with the valuable tamahagane.
