Morioka is a region rich in resources and materials that are used for iron making; everything that was necessary, such as iron sand, clay, charcoal and lacquer, was available in the area. Taking advantage of these natural resources, the Nambu clan invited artisans and craftsmen of cast ironwork from Kyoto and Koshu, retaining them within the domain to foster development of industry and culture in the region.
The Mizusawa area in the south of Iwate prefecture (present Hada-cho, Mizusawa-ku, Oshu City) also has a long tradition of cast ironwork. In fact, it has a longer history of iron-casting, dating back to the years of the Oshu Fujiwara Family, who flourished in their capital city Hiraizumi in the late Heian period (12th century).
The late Meiji period brought some more years of stagnation. However, in 1914, the former head of the Morioka clan Toshiatsu Nambu, who was a cultured man with a passion for the arts, founded Nambu Casting Institute, with an aim to refine the quality of Nambu tetsubin. The first director of the institute was Somei Matsuhashi (1871-1922), who was born in Morioka and studied casting at the Tokyo Fine Arts School, as one of the first year students of the newly founded art school.
The core is used to form the internal cavity of the tea kettle. The radius of the core is made 2mm smaller than that of the outer mold. The difference in the sizes of the mold and the core will become the thickness of the cast iron. Clay is melted in water and mixed well with sand to make the core. When the core is completely dry, it is covered with charcoal powder
The cast iron is melted in the melting pot. When the temperature is raised to 1500ºC, the impurities appear on the surface of the bright red molten iron. Impurities make the temperature inconsistent, causing problems in forming the shape of the kettle, so a rod is used to remove these impurities.
Rust Prevention (Kanake-dome)
Once the casting is finished and the core is removed, the tea kettle is baked once again in charcoal at 900ºC. This process of creating an oxide film inside the kettle to prevent rust is unique to Nambu Tekki. Furthermore, the surface of the kettle is covered with lacquer, using a special brush made from bundled water-grass called kugo-hake. Finally, it is coated with rust-preventing liquid made by putting bits of steel in acetic acid and brewed tea, known as ohaguro. Then it is wiped carefully, the handle is attached, and the lid is put in place. The Nambu tetsubin is now complete.
With thanks to Morioka Study Museum of Archaeological Site,Suzuki Shuzendo,Iwachu for their cooperation and providing materials.
Text written and supervised by Takako Yoshida, Chief Curator, Iwate Museum of Art
Text for production process by Sakai Editing and Planning
Edited by Motoki Sakai (Sakai Editing and Planning)
English Translation by Kei Kamoshida
Project Director: Shinya Maesaki, Associate Professor, Kyoto Women’s University