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Iron Teapot Production

Author: Zong Yue Photos: Zong Yue editorial department

When iron teapots are mentioned, we tend to think of Nambu ironware or Nambu tetsubin. Nambu ironware originated in Japan during the Edo period (1615-1868) in the region under the control of the Nambu Han, i.e., the area centered around Morioka. Nambu ironware developed from tea kettle production. Ironware produced in a number of other areas is also called Nambu ironware, including that of Mizusawa and today's Iwate prefecture. At the Taiwan International Tea Culture Expo held in latc-2010 in Taipei, the Mizusawa Casting Industry Cooperative, led by chairmen Oikawa Takashi, exhibited Nambu ironware to great acclaim.

Iwate prefecture is rich in iron ore and other raw materials used in the production of ironware and also produces significant quantities of paint, charcoal, and clay. The area benefitted from the protection of the Nambu Han, All of these factors provided this area with a fertile environment for development of ironware production and to this day it is still known for Nambu ironware.Previous articles on this subject focused on the growth of Nambu ironware and on introducing master casters, I hope these articles have helped fellow teapot lovers develop an understanding of the heritage and culture of these iron pots. This article is intended to help readers further understand the difficulty involved in producing fine ironware. Although I have not personally produced any ironware, I will attempt to introduce tetsubin production through the materials I have collected.

Production Process

In general, iron teapot production applied the following procedure; (1) Design and composition? (2) Wooden mold production; (3) Spout and lid production; (4) Casting mold production; (5) Casting and pouring; (6) Removal and sand stripping; and (7) Coloring and handle application.

(1) Design and Composition

The first step in iron pot production is to determine the shape and decorative features of the pot. In general it is first necessary to consider whether traditional forms and designs will be used or whether to produce an original creation. All of the following must be considered: the overall design, the size of the mouth, the shape of the spout, the design of the lid, the shape and appearance of the knob, and the colors of the pot. After determining all of these features, the design is drawn on paper maintaining the correct size proportions.

(2) Wooden Mold Production After the composition sketch is produced, a cross-section is made and used to produce the wooden mold that serves as a casting mold. The molds require approximately three sections: the upper half of the pot body, the lower half of the pot body, and the lid. The wooden molds are so named because they were originally made from wood; however, today they are commonly created from 1.5 mm sheet iron. Because teapots are hollow, the core must be produced during the casting of the iron pots. Consequently, the mold of the core is produced along with the mold. To ensure a specific thickness of the iron pot, the mold of the core is slightly smaller than that of the outer shell.

(3) Pot Spout and Lid Production

These objects refer to attached portions of the iron pot other than the body of the pot. They include the spout, knob, and rings connecting the handle to the body of the pot. An additional casting mold must be produced for each of these components. There are a number of possibilities for the shape of the knob on top of the lid, including a plum flower chrysanthemum, gourde or precious stone. Some casters may introduce their own creations own creations such as a horse, cow, or butterfly. For the rings, appropriate forms are chosen based on differences in the iron pots and may include distant mountains or devilish faces.

(4) Casting Mold Production

When the casting mold is produced, the full cast fired from the same brick material is first prepared to serve as the exterior portion of the casting mold. Then fine sand mixed clay and clay liquid are inserted in the full mold. The wooden mold is placed in the center of the full mold to serve as a scraping board.

After turn scraping is completed, the casting mold is created. This turn scraping process is referred to as "pulling the mold" in Japan. During this initial turn scraping process, the pot spout, rings, and other objects are placed in their corresponding positions. Then, using relatively fine sand mixed with clay, turn scraping is again performed. A fine sand that resembles raw silk is then used to perform the final adjustments to the mold.

After turn scraping is completed, but the sand mold is not yet completely dry, it is necessary to begin applying the design. The traditional Nambu ironware Arare (hailstone) design requires use of a metal engraving tool. Workers carefully imprint the designs one-by-one. Approximately 2000 markings must be made for a single iron pot. For other patterns, the initial sketch of the design may be attached to the sand mold before the patterns are engraved.

The core is also produced at this time. Core production is done in a similar fashion to the casting mold. The wood mold of the core is turn scraped to produce the sand mold. Casters generally divide the above and below sections into two casting molds. After the sand molds are produced, the inside is filled with sand and clay liquid is used to connect the upper and bottom halves. After drying in the sun, the core is removed. Finally, after the casting mold has dried, it is roasted in a charcoal fire to complete the production of the casting mold.

(5) Casting and Pouring

After the casting mold is completed, the tipper and Lower halves are joined together and the core is placed in the middle. On the casting mold the base of the iron pot is pointed upward, and the overall state of the mold is inverted. Likewise, the base of the core points upward. Two or three small iron sheets or other metal pieces are place between the bottom of the core and the casting mold to prevent it from floating around during pouring. After the mold is put together, the kiln is heated to 1400-1500 degrees Celsius to melt the iron before pouring it into the mold.

(6) Removal and Sand Stripping

After pouting is completed and the mold has cooled, the casting mold can be broken apart to remove the finished product. Sand stripping can then be performed, which basically involves using a metal pick to break up the core and other attached pieces. Bits of iron may jut out in the areas connecting the upper and lower casting molds. These are removed by gently tapping the pot or by using a grinding tool.

The formed iron pot is placed in an 800 to 1000 degree charcoal kiln to roast. This step is intended to cause the iron pot to form an acidized skin membrane, which can prevent rust. This technique is said to have been invented by the famous Nambu caster Arisaka Goemon. Direct contact with the charcoal flame may cause the exterior of the pot to blacken. If so,a brush is used to clean it.

(7) Coloring and Handle Application

The caster checks whether the kettle leaks. If not, color can be applied. The iron kettle is placed in a 200 degree oven. Then paint and thick tea liquor is applied as coloring. Regarding the pot handle, some arc handmade and require the work of another craftsman, Often the handle is produced by pounding a piece of sheet iron to form round strips. Once the handle is created and applied to the iron kettle, the production process is complete.

The Language of Iron Tea Kettles

As described above, the production process for handmade iron tea kettles is extremely detailed. It involves more than 60 individual steps. Each detail must be executed with the utmost care and leaves no room for error. At least two months are required to go from the initial sketch to the completed piece. The path to becoming a professional caster takes many years. Becoming a kama master whose name is engraved on the iron pots is clearly even more difficult. Without the accumulation of experience and hard work, it is difficult to achieve acclaim. This type of traditional production method differs from large-scale mechanical production. The skill of the carter is evident in each step of the production process. Each trance left behind by the production process reveals its purpose.

It is worth mentioning, however, that handmade iron kettles created using traditional techniques often contain minor defects. For example, there are often small casting defects where the core and pot meet. Consequently, a Japanese phrase has been passed down in casting workshops that roughly translates to "six intact." The meaning is, even if a complete iron kettle has six defects, it cannot be considered a failure. It can still be used after these defects are fixed. From this, we can see that a flawless tea pot without the slightest defect is not easy to produce. It requires the highest level of care at each step.

From the production procedure, we can also clearly understand the basic characteristics of handmade tea pots. Each workshop has its own production techniques, however, and casters each pursue their own casting methods, which prevents us from speaking in broad generalities. For pots produced using the methods described above, though, we should be able to vaguely make out the marks left where the upper and lower casting molds meet. On the bottom of the pot, we should where the iron was poured as well as the marks left behind by the iron or other metal pieces used to keep the core in place.

Each iron pot expresses its language through different means, telling the story of the techniques and craft of the caster, Through careful observation and appreciation of this language, you should be able to find the pot that speaks to you.