Otani ware Otani yaki
A unique production method exemplified by the nerokuro technique
Climbing kilns producing the finest large ceramic masterpieces anywhere in Japan
Otani Ware is a form of ceramics that is the most famous product of Oasacho, Naruto City in Tokushima Prefecture, and represents the prefecture.
The characteristics of Otani Ware are its clay, which brings about a simple texture, and its production method exemplified by use of the nerokuro technique. The clay used in Otani Ware is Hagiwara clay collected locally in Hagiwara, Oasacho, and equivalent clay. This clay has a high iron content, and many people love its rough texture and feel, which gives off a faint luster. Nerokuro is a casting technique whose name is derived from the fact that the artisan lies beneath the work unit when producing pieces such as large jugs that are the height of an adult. Also, the climbing kilns used to bake large ceramics are said to be the biggest kilns in Japan. There is a wide variety of Otani Ware products: besides large ceramics, there are also articles used in everyday life, such as rice bowls and teacups, and all kinds of ornamental products. Dark brown pottery is the mainstream, but there are also deep silver and gray pieces.
Otani Ware is said to have begun in 1780, during the latter part of the Edo Period, when porcelain craftsman Bun-emon from Bungo Province (now Oita Prefecture) visited Otanimura (now Oasacho, Naruto City) and produced pottery with red clay by means of lathe work.
In 1781, the 12th Lord of the Domain, Haruaki HACHISUKA, took an interest in pottery and ordered that a Domain-managed kiln should be established in Otanimura, and thus the first dyed porcelain came to be produced in Awa Province (now Tokushima Prefecture).
By 1784, the work of indigo dye merchant Bungoro KAYA (Sozaemon KASAI) led to the renboushiki climbing kiln in Otanimura being built as a “national kiln” for the baking of pottery used as daily necessities.
Production of pottery began at this climbing kiln, centered on Heijibei NODA, who had obtained techniques by employing Shigaraki Ware artisans, and this was the prototype for modern-day Otani Ware.
General Production Process
- 1. Grinding
The raw material of clay is collected is ground into fine pieces after drying.
- 2. Sieving
The ground clay is sieved, and is purified by removing foreign matter.
- 3. Elutriation
After purification, clay is placed inside a water tank and the stirring process begins. The clay is gradually transferred by pouring soil into another water tank while stirring.
Once the transfer has been completed, foreign matter is caught in a sieve, and the articles are then left for a while until the potter’s clay that forms the raw material for porcelain settles. The settled potter’s clay is moved to a mori pot, and is left until it becomes moderately hard.
- 4. Clay kneading
While the artisan steps barefooted on top of potter’s clay spread into a round shape, using both feet to tread so as to push out the clay, araneri kneading is carried out to make the whole piece of clay evenly soft.
Next, using the hands, kikuneri kneading is performed to extract air from inside the clay while rotating the clay that has already been kneaded by foot.
- 5. Casting
Clay is moved onto a lathe, where it is shaped by hand.
When producing large ceramics, artisans work in pairs to use Otani Ware’s traditional nerokuro casting technique to produce casts.
- 6. Drying
Articles that have been cast are then dried indoors by drying in the shade. When producing large ceramics such as jugs and pots, the drying process will take about 20 days. For small pieces of pottery, drying typically requires a period of between 2 and 7 days.
Next, the pieces are moved outdoors to be dried under sunlight. Here, large pieces are dried for around 2 or 3 days, and small pieces are typically dried in about 1 day.
- 7. Glazing
Once the pieces have been dried under sunlight, the next process is to glaze with enamel.
There are three main methods of glazing: namagake, in which enamel is applied without bisque; hitashigake, in where articles are soaked in enamel after bisque; and nagashigake, where enamel is poured over the articles using a ladle.
Moreover, the bisque process takes between 8 and 16 hours in a kiln at a temperature of around 800 ℃.
- 8. Loading pots into the kiln The pots are loadied into the kiln in an orderly way for baking.
- 9. Firing
The kiln temperature is set to around 1,230 ℃ before moving on to the firing process in which the articles are baked.
There are three types of kiln - climbing kilns, electric kilns, and gas kilns - and the period of time required for firing is different in each type of kiln.
In climbing kilns, 5 to 6 days and nights are required, while electric kilns and gas kilns require 1 to 2 days.
- 10. Inspection The articles are removed from the kiln and are checked for chips and cracks.
- 11. Completion Only items that have passed the inspections are sold as finished articles.
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