Shodai-yaki, a pottery with a 400-year history
Features
Shodai-yaki is a type of pottery produced in the northern part of Kumamoto Prefecture. 400 years ago, Shodai-yaki began with a technique of pouring a glaze made from straw and rice. In 2003, the Minister of Economy, Trade and Industry designated it as a national traditional craft.
Made of coarse clay with a high iron content, Shodai-yaki has a rugged and dignified appearance. Like YokkaichiBanko-yaki or Iga Yaki, it is characterized by a powerful impression that brings to the fore the metallic texture contained in the clay. It is the opposite of Kiyomizu-yaki and Mashiko-yaki, which have a delicate texture.
Shodai Pottery can be roughly divided into three lines: Ao-Shodai, White-Shodai, and Yellow-Shodai. These differences in coloration are caused by differences in glaze formulations and firing temperatures. Straw ash, wood ash, and feldspar are used as glazes, and when the straw ash and the iron in the clay are combined, a blue color is produced, resulting in a blue Shodai. If a larger percentage of straw ash is used in the glaze, the glaze becomes white, and if a larger percentage of wood ash is used, the glaze becomes yellow. The fascination lies in the fact that beautiful blue, white, and yellow colors are produced by subtle changes in the ingredients contained in the glaze.
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| source: FRANK |
Manufacturing Method & Process for Shodai-yaki
1. Collection of raw clay
The raw clay for Shodai-yaki is collected from the clay layer near Mount Kotai in Arao City, Kumamoto Prefecture. This clay, called “Shodai clay,” contains a large amount of iron and pebble grains, and is responsible for the rough, rustic texture that is characteristic of Shodai-yaki.
2. Drying
The collected clay is placed outdoors to dry under the sun. Drying under the sun removes excess alkali and prevents cracks and flaws from forming.
3. Water Filtration
After the dried clay is crushed, it is stirred with water in a tank to make muddy water. During this process, dust, sand, stones, etc. that settle are removed and the muddy water is strained into another tank. Leave the clay to dry in the sun in an unglazed pot or the like.
4. Nekashi
When the clay is dried and becomes appropriately hard, it is moved to indoor storage. Leaving the clay for a while is called “kneading,” in which bacteria in the clay multiply and their secretions make the clay particles finer, resulting in a smooth, soft, and sticky clay. The finer the clay particles, the less likely it is to shrink and crack, and the stickier the clay, the easier it is to work with. Therefore, the process of “nekashi” is considered to be an important process in pottery making.
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| souce: Kumamoto guide |
5. Kneading
Matured clay is kneaded well to remove air from the clay. Soil kneading consists of two processes: “rough kneading” and “chrysanthemum kneading. In the first process, “Arakneading” is done by using a foot or a clay kneader to make the clay uniformly soft. Next, the air contained in the clay is pushed out by “Kikkuneri,” in which the clay is kneaded firmly by hand. Through repeated kneading, the clay becomes uniformly hard and stretchy with no air bubbles. This process also prevents the formation of scratches and makes molding easier.
6. Molding
There are several techniques for molding. There are “rokuro molding” using a potter’s wheel, “kataoshi molding” using a plaster mold, “hand twist molding,” “tatara molding,” in which clay is made into sheets and combined, and “string making molding,” in which clay is made into strings and shaped.
7. Finishing the clay
This is the finishing process that takes place one to two days after the molding process, when the clay has reached an appropriate level of hardness and has not yet dried. In addition to shaving the base and attaching the mouth and hands of the teapot, chamfering, openwork carving, zogan, and other decorative processes are also carried out.
8. Drying
The clay is allowed to dry naturally in the shade, and the water is slowly removed. If moisture remains in the clay, it will crack during kiln firing, and if the clay is dried too quickly, it will not dry evenly, resulting in warping, warping, or cracking. It is important to dry clay slowly in an environment with constant humidity and temperature.
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| source: https://somekenblog.net/pr/nakaderagama/ |
9. Suyaki (unglazed)
The kiln is unglazed at 800 to 900 degrees Celsius for about 8 hours. After that, the kiln lid is left open until the heat cools naturally. Unglazing improves glaze application.
10. Glaze Preparation
Glaze is the glassy part that covers the surface of ceramics and is used to give water resistance, luster, color, and pattern to ceramics. It is made by mixing clay dissolved in water with ash, finely ground feldspar, or iron-bearing ores. Ashes can be derived from plants such as straw, bamboo grass, and thatch, or from trees such as thickets, oak, cedar, and pine.
11. Glazing
Glazes used in Shodai-yaki are charcoal glaze, straw ash glaze, bamboo grass ash glaze, thatch ash glaze, and iron glaze. Color variations are obtained depending on subtle differences in glaze formulations, temperatures and conditions during firing, and are classified into three distinctive systems: blue Shodai, yellow Shodai, and white Shodai. Glazing techniques that are said to be characteristic of Shodai ware include “soaking,” “ladle hanging,” “uchikake-nagashi,” “blow hanging,” “nurikake,” “itchin hanging,” “snake eyes,” and “nijikake.
12. Kiln Filling
The kiln is filled with items to be fired. The firing process takes into consideration the bonding of the pieces to be fired, the amount of ash on them, their shrinkage and softening, and the height and orientation of the pieces, as well as how well the fire will circulate and pass through the kiln.
13. Main firing
While unglazed pottery is fired at 800 to 900 degrees Celsius, the main firing process takes about 10 hours at a high temperature of 1300 degrees Celsius. It is important to match the firing conditions with the season and weather conditions, as these will affect the degree of firing.
14. Removing the kiln
After firing, wait for the temperature to cool naturally before removing from the kiln. Opening the kiln lid before the temperature has cooled may result in broken pieces. It takes about 10 hours for the temperature to cool completely.
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| source: https://somekenblog.net/pr/nakaderagama/ |
Keys
Ojiro-yaki has been produced in Kumamoto for about 400 years, and has recently been attracting attention from “pottery lovers” all over Japan for its simple and indescribable tasteful design and reasonable price. In terms of name recognition alone, it is no match for famous ceramics such as Arita-yaki, Shigaraki-yaki, or Mino-yaki, but it is a traditional Japanese craft that is slowly gaining popularity.
