What is TATARA Ironworks?

Tatara ironworks is a traditional method for smelting iron composites via simultaneous combustion of iron-sand and charcoal. This method remains the only method that can produce Tamahagane, a special type of steel used for sword crafting, even to this day.
Tatara ironworks had long been operated around the Chugoku Mountains, as the area is abundant in natural resources conducive to ironmaking. The region is rich in granite, for example, which contains high-quality iron-sand. The large areas of forests also allowed for an ample charcoal supply required in the smelting process during ironmaking. This region once flourished as a center of iron production. At its peak, between the late Edo period and early Meiji period (late 18th century to the 19th century), 90% of total domestic iron production took place in this region. The town of Yoshida, Unnan City, was the home of the Tanabe family; it was the most influential business family in the Tatara business in this region. The Tatara workshop operated by this family, called Takadono, is no longer in operation. However, their facility is the only surviving example of Takadono in Japan and is now open to the public.

Inheriting the Expertise

The master engineer who was responsible for the technical aspects of Tatara ironmaking was called Muraghe. He oversaw every operational process that required high accuracy in judging the timing as well as the amount of iron-sand or air to be charged into the furnace. The expertise and tacit knowledge of these master engineers have been cultivated over many years and passed down through the generations.

Iron-sand Extraction

Iron-sand used for the Tatara operation was extracted manually by a mining method called Kanna-nagashi. In this method, pickaxes were used to scrape off the topsoil of hillsides, which dislodged the soil containing iron-sand; the dislodged soil was then poured into a sluice and flushed down to a screening site. At the site, the iron-sand was refined and finally collected using the gravity concentration method. The iron-sand was sourced from not only the mountains but also from the riverbed of the Hii River.

Charcoal Making

Two types of charcoal were used in the Tatara ironmaking process: one was called Oh-zumi, which was fuelled into the furnaces, and the other was called Ko-zumi, which was used for the decarburization process in blacksmithing. As an enormous quantity of charcoal was required, the Tesshi (the Tatara owners) owned vast forests and mountains to meet the demands. Being the most influential family during the period, at their peak, the Tanabe family owned 25,000 ha (250k㎡) of forests and mountains; an area larger than the entire present-day Osaka City (225.2k㎡).
Ironmaking Process
Three types of iron were produced by the Tatara method: (1) finest steel called Hagane, (2) pig iron called Zuku, and (3) an iron compound containing impurities called Bukera. Together, they constitute a massive ferrous composite called Kera, formed as a result of deoxidation when charcoal and iron-sand are combated together. One cycle of operation ran continually for three days and three nights; this cycle was called Hitoyo. The total amount of raw materials consumed in one operational cycle was 12 tons of iron-sand and 13 tons of charcoal, and approximately 3 tons of Kera was produced. At the Tanabe’s main ironmaking site, Sugaya Tatara in Yoshida Town, the operation was carried out approximately 60–70 times a year.
TATARA Furnace and Its Underground Structure
Tatara furnaces were made of clay, and their size gradually increased over time with improvements in the bellows for air supply and underground structures for dehumidification. By the latter half of the Edo period (i.e. around the latter half of the 17th century), the Tatara furnaces were installed in workshop buildings called Takadono. The furnace of Sugaya Tatara, restored as a part of conservation works, measures 3.0 m ×1.35 m with a height of 1.2 m. It was considered the most suitable size for Tatara operations at the time. The clay that forms the inner walls of the furnace acted as a medium for a chemical reactions that resulted in the discharge of impurities or slag called Noro during the smelting process.
The flame temperature during the operation had to be maintained as high as 1,300–1,500 ℃. Thus, it was essential to dehumidify and isolate the furnace from any moisture that may rise from the ground, to avoid phreatic explosions. For the purpose, large scale underground structures were constructed to keep the furnace bed dry. The construction methods were secrets of Muraghe, and each region had different characteristics.
Air Supply Equipment
Substantial amounts of oxygen were required to be input into the furnace during smelting. Foot bellows with a seesaw mechanism were called Tenbin Fuigo; these were invented between the late 17th and early 18th century in the Chugoku region. The introduction of new bellow types resulted in a drastic change in the productivity of the furnace. Prior to 1906, air supply had long been operated manually; water-wheel generated bellows were introduced to Sugaya Tatara in this year.

Iron Produced by TATARA Operation

The large amount of ferrous composite produced by the Tatara operation is called Kera. Kera was carried into a workshop called Dohba, being crushed into smaller pieces, and was sorted based on quality. The hardest and finest quality steel of Kera that contained the least amount of carbon, was called Tamahagane. It was mainly used for crafting Japanese swords. The relatively low quality components were called Zuku and Bukera, which were forged into flat bars called Wari-tetsu (or Hocho-tetsu) after decarburization at the Oh-kajiba workshop. The Tanabe family’s historical records suggest that the total output of steel remained at approximately 20% of the entire production at Sugaya Tatara, with Zuku and Bukera making up the remaining 80%.

《Ironmaking Process》

Furnace MakingBuild a furnace using a specially mixed high-quality clay over the furnace bed created by rammed ash.
IronmakingDay1Begin the operation: Fire up the furnace to dry it out, then pour iron-sand into the furnace. As Kera begins to form, the operation becomes stable.
Day2Kera continues to increase. More iron-sand and charcoal are charged.
Day3Continued addition of iron-sand and acceleration of air supply. Discharge of unwanted slag and termination of iron-sand addition.
Day4Demolish the furnace and remove Kera once the air supply is stopped.



Tatara ironworks required two different types of blacksmithing. Oh-kaji is a process to remove impurities from Zuku and Bukera, to produce Wari-tetsu (Hocho-tetsu) through decarburization and forging. Tanabe family used to own Oh-kaji workshops close to their residential property, since Wari-tetsu (Hocho-tetsu) was their primary product for their business during the late 17th century. On the other hand, forging kitchen knives, farming, and carpentry tools were called Ko-kaji, which used Wari-tetsu (Hocho-tetsu, meaning kitchen-knife iron) as the crafting material. Japanese swordsmithing is a type of Ko-kaji.

Iron Distribution and Transport
The iron produced in the remote mountainous village of Sugaya Tatara was carried by horses to riverbanks and transshipped to Uryu Port (Izumo City) and Matsue Port (Matsue City) through Mitoya River and Hii River. All products were finally shipped out by merchant’s vessels and distributed to Osaka or the Hokuriku region, the northern coastal region of the main island. The Tanabe family also owned their own merchant vessel named Tessen-maru for making deliveries.
Kanayago Worship
Kanayago goddess is a female deity for ironmakers; she is still worshipped by workers who are employed in the metal industry today. According to a legend, she flew down on a white heron from Harima Province (Hyogo Prefecture) to Noghi County in Izumo Province (Yasughi City, Shimane Prefecture) where she landed on a branch of Cercidiphyllum Japonicum, and introduced people to iron making. There is a small shrine at Sugaya Tatara Ironmaking Village in which the Kanayago goddess is enshrined. There is also a small altar inside of Takadono where Tatara crews prayed whenever they began or finished their operations.

TATARA Industry and its Prosperity in Unnan Area

Unnan area lies in the water basin of the Hii River that runs through the city from south to north. Its prosperity was attributable not only to ironmaking, iron-sand extracting, charcoal making, iron distribution, and crafting of iron products, but was also supported by agriculture, forestry, and commercial activities. Many markets were held here; the flow of people and products created vibrant atmospheres. Especially, Kisuki Town in Unnan City flourished as a centre of iron distribution and blacksmithing. Rice threshers, known as Kisuki Senba, were made in Kisuki Town; these were popular and were sold nationwide.

Ironmaking Policy in Matsue Domain

Iron produced by the Tatara operation had become a specialty of Izumo Province during the Edo period. It was highly valued as a primary industry by Matsue Domain, which governed the region. The ironmaking industry developed under the patronage of Matsue Domain by the setting a protection policy by the Domain over the industry and restricting the number of Tesshi to assure them enough natural resources for ironmaking. Thus, their outputs increased and were distributed all over Japan as iron became the common material for making products of daily use that supported society’s development during the Edo period.

Japan’s Heritage: ‘Izumo Tatara Chronicle, A Thousand Years of Iron’

Although the Tatara ironmaking industry terminated a hundred years ago, the art and expertise are still alive and vibrant today. A group of tangible and intangible cultural heritages associated with Tatara ironworks that remained in Unnan City, Yasughi City, and Okuizumo Town are accredited as Japan’s Heritage of ‘Izumo Tatara Chronicle, A Thousand Years of Iron’ by the Agency for Cultural Affairs in 2016.