1. History of Nittoho Tatara
The Japanese sword is one of the world’s great steel works of art. Tatarabuki is the ancient Japanese method of producing tamahagane, the material used in traditional Japanese sword production.
Oku-izumo, now locating in Shimane prefecture of the San’in region, has been the center of the tatarabuki method of steel production since ancient times. However, this method was discarded following the introduction of modern steel manufacturing techniques in 1925. During the war, the increasing demand for military swords prompted the revival of the tatarabuki method and the founding of the Yasukuni Tatara in Oku-izumo in 1933. However, the tatara was closed following Japan’s defeat at the end of the Second World War in 1945.
The Nihon Bijutsu Token Hozon Kyokai (NBTHK) was founded after the war. Its primary goal was to preserve the Japanese sword and its manufacturing techniques as a traditional culture. In 1976, the NBTHK assumed responsibility of the Yasukuni Tatara under the patronage of the National Treasury. Later, the tamahagane production process was recognized as a Traditional Craft Designated for Preservation by the Minister of Education.
In addition to producing steel, the Nittoho Tatara also trains craftsmen in tamahagane production. The tamahagane is distributed to swordsmiths all over Japan and contributes to the preservation of the traditional skills of Japanese art sword production.
In 1977, the late Nittoho Tatara operators Yosizou Abe and Kanji Kumura were appointed as the Selected Conservation Technology title holders. Other recipients of this title include Akira Kihara in 1986, and Katsuhiko Watanabe in 2002.
2. Nittoho Tatara as Selected Conservation Techniques and Kera Display
Nittoho Tatara is a large traditional furnace for producing iron and steel. It is operated by The Nihon Bijutsu Token Hozon Kyokai (NBTHK). Tatarabuki is designated as a Selected Conservation Techniques. The system of designating Selected Conservation Techniques was established through an amendment to the Law for the Protection of Cultural Properties in 1975 for the purpose of supporting important intangible cultural assets. 29 groups and 52 people are recognized as Selected Conservation Techniques as of 2010.
Tatarabuki is operated every winter. The large block of iron and steel (Kera) displayed in front of the main entrance was the one manufactured in 1982. The Kera weighs at about 2.5t. It was manufactured from 10t iron sand and 12t charcoal in the old traditional way. It takes 3 consecutive days and nights. The iron sand called “Masa” is carried from the San’in area and the charcoal called “Tatara zumi” is specially produced for Tatara. After cooling down, the Kera is broken into small pieces and selected by quality. Japanese swords are made from these pieces of steel and iron.
3. The Underground Structure of Nittoho Tatara
Moisture is the adversary of the Tatarabuki method of steel manufacture. To produce high quality steel, it is imperative that all moisture be removed. In order to do this, the tatara is operated at winter time when moisture levels are at their lowest. It can be said that the history of the tatara has been a battle with moisture this method of steel production uses an underground structure with air ducts (kobune) to remove moisture during the manufacturing process. This method is the result of knowledge acquired through trial and error passed down by generations of tatara operators.
The Nittoho Tatara has revived the Tatarabuki method of steel production by utilizing the underground structure of the former Yasukuni Tatara.