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AMERICAN STYLE RAKU
by.Gus Morcate
HIGHLIGHTS OF RAKU HISTORY
Raku ware was created in 16th century Japan for ritual tea drinking. The Japanese tea ceremony, with its roots in Zen Buddhism, is a kind of meditation. The underlying philosophies are harmony, respect, purity and tranquility. The Raku type of tea bowl with a natural and unpretentious style and earthy colors was developed to enhance the experience of those participating in the ceremony.
Raku is a very hands on process. The tea bowls are fashioned by hand to be thick enough to keep the bowl from becoming too hot to hold, but thin enough to warm up and retain the warmth of the tea. Raku ware is removed from the kiln while still glowing hot, causing a forced cooling at air temperature that is a thermal shock treatment. The low firing temperature keeps the clay from completely hardening. This gives the tea bowls the insulating qualities that keep the tea warm longer and a softer feel, which makes them more appealing to hold in the hand. The distinctive sound the Raku tea bowls gives when struck is valued in the Zen experience of the Japanese tea ceremony.
Zen Buddhism originated in India and subsequently traveled to China in the sixth century A.D. where it developed further. Tea drinking in Japan dates back to the eighth century, when tea was introduced by Japanese monks trained in China. The monks originally used tea to help them stay awake during long sessions of meditation. Ritual tea drinking was first practiced in Japan during the Kamakura period (1192-1333) by Zen monks. In the 13th century, samurai, Japan’s warrior aristocracy, took it up. During the 15th century ritual tea drinking became an eclectic social art form where a group of friends gathered in an isolated atmosphere to drink tea and discuss the aesthetic merits of paintings, calligraphy and flower arrangements on display in the Tokorama of the teahouse. The tea ceremony developed in the brilliant and luxurious days of Higoshiyama and Monoyama. Passing through the hands of Shuko and Sho-o it finally took shape under those of Sen Rikyu as Cha-no-yu, or the “way of tea."
Sen-No-Rikyu, a tea master at the 16th century court of the military dictator Toyotomi Hedeyoshi, codified the ceremony into a style known as wabi, meaning simplicity, quietude and absence of ornament. Rikyu became an art director and commissioned craftsmen to create original objects in this new sensibility so this period of Japanese ceramics is call Cha-no-yu.
Tea bowls in the Cha-no-yu period are divided into three classes: Chinese, Korean and Japanese. The Chinese Temmoku and Celadon tea bowls are artistically fine and pleasing to look at, but they are not good for tea drinking because of their hardness. Korean potters kidnapped during invasions of Korea developed their own line of organic and rustic pottery in Japan.
The originator of Raku was Chojiro, the son of a Chinese emigrant. When Shogun Hideyoshi built the pleasure pavilion Ju-raku-tei he brought Chojiro to live there and had him make tiles and tea utensils. Chojiro was given an income so that he did no more commercial work and was formally appointed tea bowl maker to work under Rikyu. Hediyoshi gave Chojiro a golden seal bearing the second character of Ju-raku-tei, and hence the character “Raku" was stamped on his tiles and pottery. His wares were usually glazed with one or two colors. It is known as Raku ware and is still classified as either black or red ware. Chojiro adopted the term “Raku" as the name of the family producing the ware, not in the character’s normal sense of “joy" or “ease."
The Japanese tea masters developed a sensibility called wabi-sabi. The first recorded wabi-sabi tea master was Murata Shuko (1423-1502), a Zen monk from Nara. About a hundred years after Shukos innovations came Sen-No-Rikyu (1522-1591). The closest English equivalent to wabi-sabi is “rustic." It shares some characteristics with what we call “primitive art," that is objects that are earthy, simple, unpretentious and fashioned out of natural materials. Wabi-sabi was a reaction to Chinese perfection, much as our own Modernism is a reaction to Classicism.
Wabi is what the tea master Sen-No-Rikyu and his successors endeavored to create with the rustic teahouse, the bowl of muted colors and the single flower immaculately arrange in the dark alcove. The Japanese tearoom was much like an ordinary study in its furnishing with boxes for stationary, ink stone, bookstand, incense burner and flower vase. Since the tearoom is modeled on the pure spotless ideal world of Buddhism meditation, all luxury and all ostentation must be avoided.
A consequence of this belief led educated men to leave their rich palaces and comfortable homes to stay in a poor hut in the forest or by a lake away from the world and concentrate on just being. It was used by the powerful to escape the demands of the day-to-day.
AMERICAN RAKU
Chojiro probably glaze-fired his Raku ware in a coal or wood-burning muffle kiln and watched the firing through a hole in the lid. (The muffle kiln is a thin-walled cylinder protecting the ware from direct contact with flames it is like a protective box or saggar, but is permanently part of the kiln structure.) When the color of the kiln’s interior was right, the ware would be removed red-hot from the kiln with long-handled tongs and would be quenched by immersing it in a concentrated solution of green tea.
The American method of glaze firing Raku ware differs from the Japanese method in that after the red-hot piece is removed from the kiln, instead of quenching it, the piece is placed in a metal can with a combustible material, like paper. The combustible material ignites, and the fire and smoke reacts with the glaze to create a very unique and unpredictable effect on the surface of the pottery. This process is called post-fire reduction. After about 20 minutes, when the can has cooled down, the piece is cooled quickly with water mist to freeze the colors.
Using a combustible material in a metal can was discovered by accident in 1960 by American professor Paul Soldner during a demonstration of the Raku process. The piece he was moving from the kiln to the quenching bath fell into some dried leaves and ignited them. He liked the results, so the post-reduction process was born.
SOME PRACTICAL ADVICE
· The glaze firing should be done outdoors since the process is messy and smoky.
· After the bisque firing is completed and the glaze is applied, allow the pots to dry for a day to keep them from blowing up during glaze firing.
· When lighting the gas burners for the glaze firing, it is important to place the fire against the opening of the burner before turning on the gas and to keep the lid of the kiln off until after the burner is lit so gas doesn’t build up in the kiln. Place the burner about two inches outside the kiln wall with the flame extending into the kiln to allow sufficient air to the flame so secondary air is pulled into the kiln and complete combustion occurs. Usually it takes between 20 and 60 minutes for the glaze to melt. Most glazes go through a boiling stage during melting. Normally, the bubbles disappear when melting is complete.
· Be quick in taking the piece out of the kiln, putting it into the reduction container and covering the container before the piece has a chance to cool too much. Otherwise, the post-reduction will not be effective. After placing the piece in the can, add more shredded paper on top. Then reduce the oxygen in the can by putting a wet newspaper blanket on top of the container to put out the flame.
· While the glaze is liquid it is reactive to the post-firing "reduction" treatment, making the surface susceptible to the can atmosphere. (The oxygen is withdrawn from the copper oxide in the glaze by the oxygen greedy carbon monoxide.) The formation of the colors and surface effect occurs during this period. Any area not covered with a glaze will turn black from the smoking.
· Leave the piece in the can for 20 minutes, until the can has cooled considerably. Then cool the piece quickly with water mist to freeze the colors. Never plunged it directly into water upon removal from the glaze firing kiln.
· Preparing the glaze material consists of weighing out of each raw material in grams or parts, mixing the ingredients with water and finally screening the entire solution through a 50 to 60 mesh sieve. The consistency of copper matt surface patinas should resemble watery, thin milk. All others glazes should be very thick like yogurt. One gallon of glaze takes about 2000g of dry raw materials.
· Glaze fades away in Raku because of lack of glass in the recipe. Good glass needs silica, and the Raku glazes lack sufficient silica to form a durable glass. Good glass does not come from impure Calcium Borate like colemanite and gersley borate, which are used in Raku glazes. Instead, the overall result is an ultra thin layer of colored glass on the surface. Unfortunately these surfaces are very susceptible to re-oxidation. The sulphur compounds polluting city air very quickly destroy the surface. The glaze is too porous and is easily affected by the environment. To delay oxygen penetrating the Raku glaze, the piece may be sealed with silicon polish or slow drying epoxy.
· When building the glaze firing kiln, line the can with RFC (refractory ceramic fiber). Since the fiber can become airborne during construction and enter the lungs, always use a NIOSH approved respirator for mineral dust and wear long sleeves, a head covering and eye protection. Once the RFC is in place, dust is not really a problem. Hold the fiber with buttons made of clay and attached to the wall of the can with high temperature wire. Add a venturi burner with a valve, a high-pressure hose, a high pressure regulator (with a valve) attached to a propane tank and fire it up.
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