Six Key Steps in the Production of Nanbu tetsubin
1. Design/wooden model making / デザイン・木型作り
2. Katahiki (mold creation) / 型挽き
3. Pressing patterns / hada-uchi (surface treatment) /文様押し・肌打
4. Iron casting / 鋳込み
5. Kamayaki (firing in a pot) / 釜焼き
6. Coloring / 着色
It is said that there are more than 100 processes to complete one tetsubin. Among them, the most distinctive and important are design/wooden model making, katahiki (mold creation), pressing patterns/hada-uchi (surface treatment), iron casting, kamayaki (firing in a pot), and coloring.
鉄瓶の完成までには100以上の工程があるといわれています。そのなかでも特徴的かつ重要なのは、「デザイン・木型作り」、「型挽き（かたひき）」「文様押し・肌打」「鋳込み」「釜焼き」「着色」です。
1. Design/wooden model making / デザイン・木型作り
Making tetsubin starts by coming up with a design. Once the design is decided, an iron plate model called a wooden model (so called because it used to be made of wood) is made based on the design, using an electric saw and several types of files. This is the most important process because if there is even a 1 mm deviation in this wooden model, no correction can be made to the very end.
鉄瓶作りは、デザインを考えるところから始まります。デザインが決まると、「木型」と呼ばれる鉄板の型（かつては木製だったためこう呼ばれています）を電動ノコギリと数種類のヤスリを使用し仕上げていきます。この木型に1mmでもずれがあると、完成まで修正することができないため、最も大事な工程です。
Numerous wooden models accumulated over the course of history
これまでの歴史で蓄積されてきた数々の木型
2. Katahiki (mold creation) / 型挽き
A wooden model is fixed inside a frame made of brick-like material. A casting mold is created by rotating the wooden model while coating with river sand, water, and hajiru, which acts as an adhesive. River sand from Mt. Iwate, which is an active volcano, is fireproof and does not melt even when burned at high temperatures. This is thought to be one of the reasons why Nanbu Tekki was so widely produced in the region. The mold is made of sand and can be reused.
木枠を煉瓦のような素材でできた枠の中に固定し、くるくるとまわしながら、川砂や水、接着剤となる埴汁（はじる）を塗りつけて鋳型を作ります。活火山である岩手山由来の川砂は耐火性があり、高温で焼いても溶けることがありません。このことも南部鉄器が盛んに作られた理由のひとつだと考えられます。また、この鋳型は砂でできているため再利用が可能です。
Mold creation from sand
砂から鋳型を形成していく様子
3. Pressing patterns / hada-uchi (surface treatment) /文様押し・肌打
Before the sand dries, various patterns are stamped to the casting mold according to the products, such as arare (hailstone) and sakura (cherry blossom). Then, the surface of the mold is made uneven using grains of sand. This surface treatment work is called hada-uchi. It is said to be performed both to give the surface of the tetsubin a unique texture and expression and to let the ohaguro (a liquid made from rusted iron and tea), which is applied as a finishing touch, to penetrate. The mold on which the pattern press and surface treatment have been completed is baked at high temperatures. This method is called yakigata.
砂がまだ乾かないうちに、「あられ」や「桜」など、製品に応じたさまざまな模様を押し付けていきます。その後、砂の粒で表面に細かな凹凸を施します。この工程は「肌打」と呼ばれ、風合いを引き出すため、さらに最終仕上げとして塗る「おはぐろ」（鉄の錆液とお茶で作られる）をより深く浸透させる役割もあります。模様付けと肌打が完了した後、製品は高温で焼き固められます。この技法は「焼型」とも呼ばれています。
It is a very detailed work to stamp a pattern on the surface one by one.
一点、一点、表面に文様を押していくとても細かい作業です.。
4. Iron casting / 鋳込み
In parallel with processes 2 and 3, a core is made to create a cavity inside the tetsubin, and iron heated to 1,300 to 1,400°C is poured into the casting mold in which the core is set. White charcoal is needed to start a high-temperature fire and is specially made by a local charcoal maker.
2.3と並行して内部に空洞を作るための中子を作り、中子をセットした鋳型に1,300～1,400度で溶かした鉄を流し込みます。高温の火を起こすためには白炭が必要で、地元の炭職人に特別に作ってもらっています。
5. Kamayaki (firing in a pot) / 釜焼き
The finished tetsubin is then fired at high temperatures for the formation of an oxide film. This process makes the tetsubin less susceptible to rust.
できあがった鉄器を、高温で焼き、酸化皮膜を形成します。この工程を行うことで錆にくくなります。
The firing of one tetsubin at a time in a pot
一点、一点釜焼きをする様子
Tetsubin after kamayaki 釜焼きを終えた鉄瓶
6. Coloring / 着色
After lacquer is baked onto the heated tetsubin, it is coated with lacquer and baked to further prevent rust.
To make it more durable and to highlight the pattern, an iron acetate solution (also called ohaguro or rust) is applied to provide a decorative effect to set the color tone and to prevent rusting.
漆を加熱した鉄瓶に焼付けた後、漆を塗り、焼き付けることでさらに錆止めを行います。より耐久性を高め、模様を浮き立たせるために鉄漿液（おはぐろ、さびとも言う）を塗ることで色調を整える装飾的な効果と錆び止めの効果があります。
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Temari tetsubin (Large) / 手毬鉄瓶 大
Hinomarugata tetsubin (Large) / 日の丸型鉄瓶 大
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About Suzuki Morihisa Studio / Hisitory of Nanbu Tekki