Raku
Encyclopedia
Japanese pottery
Japanese pottery and porcelain , one of the country's oldest art forms, dates back to the Neolithic period...
that is traditionally used in the Japanese tea ceremony
Japanese tea ceremony
The Japanese tea ceremony, also called the Way of Tea, is a Japanese cultural activity involving the ceremonial preparation and presentation of matcha, powdered green tea. In Japanese, it is called . The manner in which it is performed, or the art of its performance, is called...
, most often in the form of tea bowls. It is traditionally characterized by hand molded, rather than turned, clay, which results in each piece being "one-of-a-kind"; fairly porous vessels, which result from low firing temperatures; lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
glaze
Ceramic glaze
Glaze is a layer or coating of a vitreous substance which has been fired to fuse to a ceramic object to color, decorate, strengthen or waterproof it.-Use:...
s; and the removal of pieces from the kiln
Kiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...
while still glowing hot. In the traditional Japanese process, the fired raku piece is removed from the hot kiln and is allowed to cool in the open air or in a container filled with combustible material. Raku techniques have been modified by contemporary potters worldwide.
History
Raku means "enjoyment" or "ease" and is derived from Jurakudai, the name of a palace, in Kyoto, that was built by Toyotomi HideyoshiToyotomi Hideyoshi
was a daimyo warrior, general and politician of the Sengoku period. He unified the political factions of Japan. He succeeded his former liege lord, Oda Nobunaga, and brought an end to the Sengoku period. The period of his rule is often called the Momoyama period, named after Hideyoshi's castle...
(1537–1598), who was the leading warrior statesman of the time.
In the 16th century, Sen Rikyu, the Japanese tea master, was involved with the construction of the Jurakudai and had a tile-maker, named Chōjirō
Chojiro
is distinguished as the first generation in the Raku family line of potters, and according to historical documents, was the son of one Ameya, who is said to have immigrated to Japan from China , which is also asserted on the RAKU WARE website of the still active line of potters founded by Chojiro...
, produce hand-moulded tea bowls for use in the wabi
Wabi-sabi
represents a comprehensive Japanese world view or aesthetic centered on the acceptance of transience. The aesthetic is sometimes described as one of beauty that is "imperfect, impermanent, and incomplete"...
-styled tea ceremony that was Rikyū's ideal. The resulting tea bowls made by Chōjirō were initially referred to as "ima-yaki" ("contemporary ware") and were also distinguished as Juraku-yaki, from the red clay (Juraku) that they employed. Hideyoshi presented Jokei, Chōjirō's son, with a seal that bore the Chinese character for raku. Raku then became the name of the family that produced the wares. Both the name and the ceramic style have been passed down through the family (sometimes by adoption) to the present 15th generation (Kichizaemon). The name and the style of ware has become influential in both Japanese culture and literature.
In Japan, there are "branch kilns" (wakigama), in the raku-ware tradition, that have been founded by Raku-family members or potters who apprenticed at the head family's studio. One of the most well-known of these is Ōhi-yaki (Ōhi ware).
After the publication of a manual in the 18th century, raku ware was also made in numerous workshops by amateur potters and tea practitioners in Kyoto,and by professional and amateur potters around Japan.
Raku ware marked an important point in the historical development of Japanese ceramics, as it was the first ware to use a seal mark and the first to focus on close collaboration between potter and patron. Other famous Japanese clay artists of this period include Dōnyū (grandson of Chōjirō, also known as Nonkō; 1574–1656), Hon'ami Kōetsu
Honami Koetsu
was a Japanese craftsman, potter, lacquerer, and calligrapher, whose work is generally considered to have inspired the founding of the Rinpa school of painting.-Early life:...
(1556–1637) and Ogata Kenzan
Ogata Kenzan
, originally , and also known by the pseudonym Shisui, was a Japanese potter and painter, a younger brother of Ogata Korin. He was born in Kyoto in a rich marchant family and died in Edo . He had learned after the famous potter NONOMURA NINNSEI and made his own kiln. Since in 1712 a nobleman...
(1663–1743).
In literature
- Raku tea bowls play an important part in Rituals, a 1983 novel by the Dutch author, Cees NooteboomCees NooteboomCees Nooteboom is a Dutch author. He has won numerous literary awards and has been mentioned as a candidate for the Nobel Prize in literature.-Life:...
.
Oxidation Reduction
In raku firing, the aluminium container acts as a reduction tube, which is a container that allows the carbon dioxide to pass through a small hole. , Areduction atmosphere is created by closing the container . A reduction atmosphere induces a reaction between oxygen and clay, which affects the color . It also has extraordinary effects on the metals inside the glaze. Reduction is a decrease in oxidation number . Closing the can starves the air of oxygen after the combustible materials such as sawdust catch fire and forces the reaction to pull oxygen from the glazes and the clay . For example, luster duster gets its interesting color from deprivation of oxygen. The reduction agent is a substance from which electrons are being taken by another substance . The reaction uses oxygen from the atmosphere within the reduction tube, and, to continue, it receives the rest of the oxygen from the glazes . This leaves ions and iridescent luster behind. This creates a pleasing metallic effect. Pieces with no glaze have nowhere to get the oxygen from, so they take it from clay. This atmosphere will turn clay black, making an unattractive, matte color, without sheen.Reduction Firing 2
Reduction firing is when the kiln atmosphere, which is full of combustible material, is heated up. “Reduction is incomplete combustion of fuel, caused by a shortage of oxygen, which produces carbon monoxide” (Arbuckle, 4) Eventually, all of the available oxygen is used. This then draws oxygen from the glaze and the clay to allow the reaction to continue. Oxygen serves as the limiting reactant in this scenario because the reaction that creates fire needs a constant supply of it to continue; when the glaze and the clay come out hardened, this means that the oxygen was subtracted from the glaze and the clay to accommodate the lack of oxygen in the atmosphere. Consequently, the raku piece appears black or white, which depends upon the amount of oxygen that was lost from each area of the piece. The empty spaces that occur from the reduction of oxygen are filled in by carbon molecules in the atmosphere of the container, which makes the piece blacker in spots where more oxygen was retracted.Western raku techniques
Raku became popularized in America in the late 1950s with the help of Paul SoldnerPaul Soldner
Paul Soldner was an American ceramic artist.- Biography :...
. Americans kept the general process of firing, that is, heating the pottery very quickly at high temperatures and then cooling it very fast. Besides this, America has formed its own, unique style of raku.
It is raku’s unpredictable results and intense color that attract modern potters. These patterns and color result from the harsh cooling process and the amount of oxygen that is allowed to reach the pottery. Depending on what effect the artist wants, the pottery is either instantly cooled in water, cooled slowly in the open air, or placed in a barrel filled with combustible material, such as newspaper, covered, and allowed to smoke the fired raku piece is removed from the hot kiln and is allowed to cool in the open air or in a container filled with combustible material . Water immediately cools the pottery, stopping the chemical reactions of the glaze and fixing the colors. The combustible material results in smoke, which stains the unglazed portions of the pottery black. The amount of oxygen that is allowed during the firing and cooling process affects the resulting color of the glaze and the amount of crackle.
Unlike traditional Japanese raku, which is mainly hand built bowls of modest design, western raku tends to be vibrant in color, and comes in many shapes and sizes. Western raku can be anything from an elegant vase, to an eccentric abstract sculpture. Although some do hand build, most western potters use throwing wheels while creating their raku piece. Western culture has even created a new sub branch of raku called horse hair raku
Horse hair raku
Is a method of decorating pottery through the application of horsehair and other dry carbonaceous material to the heated ware. The burning carbonaceous material creates smoke patterns and carbon trails on the surface of the heated ware that remain as decoration after the ware cools...
. These pieces are often white with squiggly black lines and smoke-like smudges. These effects are created by placing horse hair, feathers, or even sugar on the pottery as it is removed from the kiln and still extremely hot.
Kilns and firing
The first working Japanese kiln in the west was built by Tsuronosuke Matsubayashi at Leach PotteryLeach Pottery
The Leach Pottery was founded in 1920 by Bernard Leach and Shoji Hamada in St Ives, Cornwall, in the United Kingdom.The buildings have grown from an old cow / tin-ore shed in the 19th century to a pottery in the 1920s when Hamada and Leach first attempted to construct a climbing kiln, this was the...
, St Ives in 1922.
It is important for a kiln to have a door that is easily opened and closed, because, when the artwork in the kiln has reached the right temperature (over 1000 degrees Celsius), it must be quickly removed and put in a metal or tin container with combustible material, which reduces the pot and leaves certain colors and patterns.
The use of a reduction chamber at the end of the raku firing was introduced by the American potter Paul Soldner
Paul Soldner
Paul Soldner was an American ceramic artist.- Biography :...
in the 1960s to compensate for the difference in atmosphere between wood-fired Japanese raku kilns and gas-fired American kilns. Typically, pieces removed from the hot kiln are placed in masses of combustible material (e.g., straw
Straw
Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...
, sawdust
Sawdust
Sawdust is a by-product of cutting lumber with a saw, composed of fine particles of wood. It can present a hazard in manufacturing industries, especially in terms of its flammability....
, or newspaper
Newspaper
A newspaper is a scheduled publication containing news of current events, informative articles, diverse features and advertising. It usually is printed on relatively inexpensive, low-grade paper such as newsprint. By 2007, there were 6580 daily newspapers in the world selling 395 million copies a...
) to provide a reducing atmosphere for the glaze and to stain the exposed body surface with carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
.
Western raku potters rarely use lead as a glaze ingredient, due to its serious level of toxicity, but may use other metals as glaze ingredients. Japanese potters substitute a non-lead frit
Frit
Frit is a ceramic composition that has been fused in a special fusing oven, quenched to form a glass, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes; the purpose of this pre-fusion is to render any soluble and/or toxic components insoluble...
. Although almost any low-fire glaze can be used, potters often use specially formulated glaze recipes that "crackle" or craze (present a cracked appearance), because the crazing lines take on a dark color from the carbon.
Western raku is typically made from a stoneware
Stoneware
Stoneware is a vitreous or semi-vitreous ceramic ware with a fine texture. Stoneware is made from clay that is then fired in a kiln, whether by an artisan to make homeware, or in an industrial kiln for mass-produced or specialty products...
clay body, bisque fired at 900 °C (1,652 °F) and glaze fired (the final firing) between 800–1000 °C (1,472–1,832 F), which falls into the cone
Pyrometric cone
Pyrometric cones are pyrometric devices that are used to gauge heatwork during the firing of ceramic materials. The cones, often used in sets of three as shown in the illustration, are positioned in a kiln with the wares to be fired and provide a visual indication of when the wares have reached a...
06 firing temperature range. The process is known for its unpredictability, particularly when reduction is forced, and pieces may crack or even explode due to thermal shock. Pots may be returned to the kiln to re-oxidize if firing results do not meet the potter's expectations, although each successive firing has a high chance of weakening the overall structural integrity of the pot. Pots that are exposed to thermal shock multiple times can break apart in the kiln, as they are removed from the kiln, or when they are in the reduction chamber.
The glaze firing times for raku ware are short: an hour or two as opposed to up to 16 hours for high-temperature cone
Pyrometric cone
Pyrometric cones are pyrometric devices that are used to gauge heatwork during the firing of ceramic materials. The cones, often used in sets of three as shown in the illustration, are positioned in a kiln with the wares to be fired and provide a visual indication of when the wares have reached a...
10 stoneware firings. This is due to several factors: raku glazes mature at a much lower temperaturee (under 980 °C (1,796 °F), as opposed to almost 1260 °C (2,300 °F) for high-fire stoneware); kiln temperatures can be raised rapidly; and the kiln is loaded and unloaded while hot and can be kept hot between firings.
Because temperature changes are rapid during the raku process, clay bodies used for raku ware must be able to cope with significant thermal stress. The usual way to add strength to the clay body and to reduce thermal expansion is to incorporate a high percentage of quartz, grog
Grog (clay)
Grog, also known as firesand and chamotte, is a ceramic raw material. It has high percentage of silica and alumina. It can be produced by firing selected fire clays to high temperature before grinding and screening to specific particle sizes. It can also be produced from pitchers...
, or kyanite
Kyanite
Kyanite, whose name derives from the Greek word kuanos sometimes referred to as "kyanos", meaning deep blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than...
into the body before the pot is formed. At high additions, quartz can increase the risk of dunting
Glaze Defects
Glaze defects are any flaws in the surface quality of a ceramic glaze, its physical structure or its interaction with the body.-Body/glaze interaction problems:...
or shivering
Glaze Defects
Glaze defects are any flaws in the surface quality of a ceramic glaze, its physical structure or its interaction with the body.-Body/glaze interaction problems:...
. Therefore, kyanite
Kyanite
Kyanite, whose name derives from the Greek word kuanos sometimes referred to as "kyanos", meaning deep blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than...
is often the preferred material, as it contributes both mechanical strength and, in amounts up to 20%, significantly reduces thermal expansion. Although any clay body can be used, white stoneware clay bodies are unsuitable for the western raku process unless some material is added to deal with thermal shock. Porcelain,however is often used but it must be thinly thrown.
Aesthetic considerations include clay color and fired surface texture, as well as the clay's chemical interaction with raku glazes.
In a craft conference in Kyoto in 1979, a heated debate sprang up between Western raku artists Paul Soldner
Paul Soldner
Paul Soldner was an American ceramic artist.- Biography :...
and Rick Hirsh and the youngest in the dynastic raku succession, Kichiemon, (of the fourteenth generation of the "Raku" family of potters) concerning the right to use the title "raku". The Japanese artists maintain that any work by other craftsman should hold their own name, (i.e., Soldner-ware, Hirsh-ware), as that was how "raku" was intended.
Raku in the west has been abstracted and is now a more philosophical approach with the emphasis on the spontaneity of surface pattern creation rather than purely a firing technique. Consequently this has expanded its application from pots to sculptural ceramics.