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The ''anagama'' kiln (Japanese Kanji: 穴窯/ Hiragana: あながま) is an ancient type of
pottery
Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and por ...
kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
brought to
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
from
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
via
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
in the 5th century. It is a version of the climbing
dragon kiln
A dragon kiln () or "climbing kiln", is a traditional Chinese form of kiln, used for Chinese ceramics, especially in southern China. It is long and thin, and relies on having a fairly steep slope, typically between 10° and 16°, up which the kil ...
of south China, whose further development was also copied, for example in breaking up the firing space into a series of chambers in the ''
noborigama
The ''anagama'' kiln (Japanese Kanji: 穴窯/ Hiragana: あながま) is an ancient type of pottery kiln brought to Japan from China via Korea in the 5th century. It is a version of the climbing dragon kiln of south China, whose further deve ...
'' kiln.
An ''anagama'' (a Japanese term meaning "cave
kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
") consists of a firing chamber with a firebox at one end and a flue at the other. Although the term "firebox" is used to describe the space for the fire, there is no physical structure separating the stoking space from the pottery space. The term ''anagama'' describes single-chamber kilns built in a sloping tunnel shape. In fact, ancient kilns were sometimes built by digging tunnels into banks of clay.
The anagama is fueled with firewood, in contrast to the electric or gas-fueled kilns commonly used by most modern
potters
A potter is someone who makes pottery.
Potter may also refer to:
Places United States
*Potter, originally a section on the Alaska Railroad, currently a neighborhood of Anchorage, Alaska, US
* Potter, Arkansas
* Potter, Nebraska
*Potters, New Jer ...
. A continuous supply of fuel is needed for firing, as wood thrown into the hot kiln is consumed very rapidly. Stoking occurs round the clock until a variety of variables are achieved including the way the fired pots look inside the kiln, the temperatures reached and sustained, the amount of ash applied, the wetness of the walls and the pots, etc.
Burning wood not only produces heat of up to 1400°C (2,500 °F), it also produces
fly ash
Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK) plurale tantum: coal combustion residuals (CCRs)is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired ...
and volatile salts. Wood ash settles on the pieces during the firing, and the complex interaction between flame, ash, and the minerals of the clay body forms a natural ash glaze. This glaze may show great variation in color, texture, and thickness, ranging from smooth and glossy to rough and sharp. The placement of pieces within the kiln distinctly affects the pottery's appearance, as pieces closer to the firebox may receive heavy coats of ash, or even be immersed in embers, while others deeper in the kiln may only be softly touched by ash effects. Other factors that depend on positioning include temperature and
oxidation/reduction. Besides location in the kiln, (as with other fuel-fired updraft kilns) the way pieces are placed near each other affects the flame path, and, thus, the appearance of pieces within localized zones of the kiln can vary as well. It is said that loading an anagama kiln is the most difficult part of the firing. The potter must imagine the flame path as it rushes through the kiln, and use this sense to 'paint the pieces with fire'.
The length of the firing depends on the volume of the kiln and may take anywhere from 48 hours to 12 or more days. The kiln generally takes the same amount of time to cool down. Records of historic firings in large Asian kilns shared by several village potters describe several weeks of steady stoking per firing.
Kiln variants
One variant on the ''anagama'' style is the ''waritake'' kiln. A ''waritake'' kiln is akin to ''anagama'' in structure, but it has partition walls built every several meters through the length of the kiln. Each partition can be side stoked.
A ''noborigama'' 登り窯 chambered climbing kiln is also built on a slope, and each succeeding chamber is situated higher than the one before it. The chambers in a noborigama are pierced at intervals with stoking ports. Such climbing kilns have been used in Japan since the 17th century. The largest working ''Noborigama'' kiln in Japan is located in
Shigaraki
is a town located in Kōka District, Shiga Prefecture, Japan.
As of 2004, the town has an estimated population of 13,885 and a density of 84.92 persons per km². The total area is 163.5 km².
On October 1, 2004, Shigaraki, along with the to ...
, in the southern portion of Shiga Prefecture.
The ''renboshiki noborigama'' is a multi-chambered climbing kiln. There are many distinguishing characteristics between the ''noborigama'' and ''anagama'' style. For example, an ''anagama'' is somewhat like a half-tube (long
vault
Vault may refer to:
* Jumping, the act of propelling oneself upwards
Architecture
* Vault (architecture), an arched form above an enclosed space
* Bank vault, a reinforced room or compartment where valuables are stored
* Burial vault (enclosure ...
) with a fire burned at the lower end. A ''noborigama'' is like a set of half-tubes (
arch
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it.
Arches may be synonymous with vaul ...
es or short vaults,
buttress
A buttress is an architectural structure built against or projecting from a wall which serves to support or reinforce the wall. Buttresses are fairly common on more ancient buildings, as a means of providing support to act against the lateral (s ...
ing each other) placed side-by-side with piercings that allow each chamber to feed into the next.
The ''jagama'' (snake kiln or
dragon kiln
A dragon kiln () or "climbing kiln", is a traditional Chinese form of kiln, used for Chinese ceramics, especially in southern China. It is long and thin, and relies on having a fairly steep slope, typically between 10° and 16°, up which the kil ...
) is related to ''anagama'', ''noborigama'', and ''waritake'' kilns, and was used extensively in China since at least the 3rd century CE. ''Jagama'' are tube shaped similarly to ''anagama'' kilns, but can be longer at around 60 m. Although partitioned and side stoked, ''jagama'' do not have partition walls, rather, improvised walls are created by densely stacking pottery at intervals.
Characteristics
The main advantage of climbing kilns is that heat from the burning fuel is re-used, the same heat heating more than one part of the kiln. Exhaust heat created during firing of the lower part of the kiln, preheats the chambers above. In addition, the cooling ware and walls below preheat the incoming air. Thus, firing of ware in the upper chambers requires only the additional fuel needed to bring the ware, walls and air to peak temperature. (From a
thermodynamic
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of ther ...
point of view, the higher temperature of combustion and cooler exhaust suggest greater efficiency.) A modern type, called a ''
tube kiln
Tube or tubes may refer to:
* ''Tube'' (2003 film), a 2003 Korean film
* ''The Tube'' (TV series), a music related TV series by Channel 4 in the United Kingdom
* "Tubes" (Peter Dale), performer on the Soccer AM television show
* Tube (band), a ...
'' improves the efficiency and output still further by having the ware move through the kiln in a direction opposite to that of the hot gasses.
All of these kilns use two ''counter-flow exchange mechanisms'' to maintain the air supply and to change the ware being fired, with minimal loss of heat. Each of these exchanges works on the same principle as
countercurrent exchange
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some chemical, between two flowing bodies flowing in opposite directions to each ...
, the principal difference being that the ware is not a fluid.
An advantage of the chambered and semi-chambered variants appears to be that they are partly downdraft, which makes the firing results less sensitive to the way the ware is loaded.
A disadvantage of smaller climbing kilns is a tendency to rapid cooling, caused by the incoming air.
See also
*
Six Ancient Kilns The Six Ancient Kilns (六古窯 Rokkoyō) is a category developed by Koyama Fujio (小山富士夫 1900–1975) in the post-war period to describe the most noteworthy ceramic kilns of Japan.
The six kilns are:
* Bizen ware (備前焼, Bizen-yaki ...
References
* {{cite web , author=Furutani, Michio , title=Anagama: Building Kilns and Firing (2003) (unpublished translation manuscript on file with anagama-west.com , url=http://www.anagama-west.com/anagama/book/anagama_translation.php
External links
* Cofield, Jay.
Montevallo's Anagama" ''Southern Spaces'', 10 June 2008.
The Log Book, the magazine about anagamas and woodfiring in generalAn anagama kiln built according to Furutani Michio's design principles, podcasts with woodfire potters, photogalleries of woodfired work* Carlson, Scott
''Chronicle of Higher Education'', 13 February 2009. A story about a potter who built the Johanna Kiln, the largest wood-fired kiln in North America.
Japanese pottery
Kilns