Noborigama (Climbing kiln) (登り窯)

"Noborigama" these days generally means a kiln with a partitioned chamber for firing large quantities of ceramics and other ware, built on a slope so that gravity draws the flue gas through the kiln, keeping the high temperatures constant throughout the chamber. This kiln works particularly well for manufacturing uniform goods when the surface of ware is coated by glaze. Before the development of transport systems, Noborigama was constructed near to where the ware would be sold or in places abundant in the raw materials of clay, fuel and water.

"Noborigama" is a general term for several types of kiln. 1. The term "Noborigama" is used for the traditional Renboshiki-noborigama (multi-chambered climbing kiln), as opposed to gas-fueled kilns, electric kilns and the Roller Hearth Kiln, used for producing advanced industrial ceramics ("Noborigama" in the narrow sense). 2.The term "Noborigama" is also used for "Anagama," built on a slope by digging holes or tunnels, which are used for baking Sue ware and porcelain at high temperatures. 3. Furthermore, the term "Noborigama" also refers to ordinary kilns, including the Chinese "Dragon kiln" for ceramics baking built on a slope ("Noborigama" in the wide sense).

Renboshiki-noborigama is Noborigama in the narrow sense, that is a kiln for baking modern ceramics => refer to "Renboshiki-noborigama"

Anagama is a underground or semi-underground type kiln for baking Sue ware and porcelain, built on a slope => refer to "Anagama"

Dragon kilns are single-chambered kilns in China for baking ceramics, built on a slope => refer to "Dragon kiln"

History
Until the early Kofun period in Japan, earthenware was baked in an oxidizing fire at sites such as baking pits for earthenware or Haji ware (a type of plain, unglazed, reddish-brown Japanese earthenware) in a manner similar to field burning. However, from the middle of the Kofun period, Sue ware and its production methods, firing in a reductive atmosphere using Noborigama (Anagama) and shaping using a potter's wheel, were introduced from the Korean peninsula. The sixteenth century saw the appearance of thermally efficient Ogama kilns capable of mass production. By the Edo period, the even more efficient Renboshiki-noborigama appeared, its half-tube shape baking rooms in a stepped arrangement advantageous for producing ware with uniform finish and giving it greater capacity. Although Renboshiki-noborigama was the most common type of kiln until recently, its number is declining rapidly.

Construction

The inside of Renboshiki-noborigama is partitioned into several baking chambers. The lowest chamber is the firebox (the kiln mouth), known as an "Oguchi." Then, several connecting baking chambers, which due to their long narrow shape look like a row of caterpillars when viewed from the side, continue up the slope. The top baking chamber is connected to a flue and chimney. A small hole called a "Koguchi" is made in each baking chamber for adding more firewood.

Baking

The temperature inside the kiln is generally kept around 1300 ℃ for baking, and products are usually baked for about sixty hours. Controlling the temperature is entrusted to the intuition of craftsman, which is quite a skilled job. Specifically, the craftsman makes subtle changes to the temperature depending on the baking stage by putting a suitable amount of firewood through the Oguchi at the lowest baking chamber and the Koguchi on each baking chamber. This task continues for fully two days and nights. After finishing the initial roast stage, a preparatory stage aimed at drying out the ware, the temperature inside the kiln is gradually raised by putting firewood through the Oguchi at the full-scale roast stage. It takes about one day to reach the target temperature of 1300 ℃. If you watch the ware through the observation hatch at this stage, you will see the heated wares change to a clear orange color.

As shown in the saying "Baked ware should be cooled for as long as it took to be baked," baked ware has to be removed from the kiln carefully. Caution needs to be exercised especially when large-sized ware is removed as it might be cracked due to the rapid temperature loss during the procedure.

Surrounded by dense clouds of black smoke, the kiln provides a spectacular sight.

Unlike Renboshiki-noborigama, the flue gases (flame) in Anagama go straight through the kiln and since there are no convection currents, the position of ware relative to the fire and the amount of ash coating produce patterns and colors that even craftsmen cannot anticipate, resulting in tasteful pieces of which it is said no two are the same. The organic and delicate finish, characteristic of pottery baked in a climbing kiln, is referred to as "Keshiki" (lit. scenery). The main fuel is pine.

Production areas using climbing kilns

Tanba tachikui ware (Konda-cho, Sasayama City, Hyogo Prefecture)

It is one of the "Six Old Kilns of Japan." The Noborigama was established using geographical features at the end of the Momoyama period after about 400 years of Anagama use, and there remain around sixty potteries.

Shigaraki ware (Shigaraki-cho, Koka City, Shiga Prefecture)

One of the "Six Old Kilns of Japan," where pottery including jars, pots and mortars (suribachi) have been produced using Anagama since around the end of the Middle Ages. This area also produced many chaki (implements used in Japanese tea ceremony) in early-modern times, and was a major manufacturer of ceramic lamps at the end of the Edo period.

Bizen ware (Bizen City, Okayama Prefecture)

One of the "Six Old Kilns of Japan," where pottery including jars, pots and mortars (suribachi) have been produced using Anagama since around the end of the Middle Ages. Many chaki were also produced in early-modern times. The ware produced is a kind of unglazed earthenware called yakijime. The ware manufactured before the early part of the Edo period is called 'Ko-bizen' and is highly valued.

Karatsu ware (Karatsu City, Saga Prefecture)

When "Karatsu" is written in Chinese characters, it means 'a Port leading to China.'
This area manufactured lots of ware for daily use such as jars, pots, plates and sake bottles in the Muromachi and Momoyama periods. This area has also produced many excellent chaki.

Naraoka ware (Daisen City, Akita Prefecture)

The birth of Naraoka ware dates back to 1863, when Seiji KOMATSU, a member of an old local family, invited a potter of the Terauchi ware style to construct a kiln. The ware is known for its vivid blue color.

Mashiko ware (Mashiko-cho, Tochigi Prefecture and others)

Influenced by Kasama ware, the manufacture of Mashiko ware started in the middle of the nineteenth century. This area produced many pieces for daily use, many of which were used in Edo as well.