watPine Garden Bonsai Co. - Clay Article

Pine Garden Bonsai Co.

20331 S. R. 530 NE
Arlington, WA 98223
phone (360) 435-5995 fax (360) 435-4865

Everything You've always Wanted to Know About Clay but Didn't Know Who to Ask

by Max Braverman

About the Author/Pine Garden Bonsai

Recommended Books

Clay is found everywhere. Mixed with water to a workable consistency, it can be shaped. Once fired, clay becomes hard and insoluble. How much of human social development is a consequence of that simple clay technology that creates bowls where only mud stood before.

The technology of working clay hasn't changed in six thousand years since potters of the Yang-shao (Yellow River) culture in China's Kiangsu province shaped painted pottery water jugs.

One can only guess at how the pottery of six thousand years ago was formed? Was wet clay pressed against the side of a woven basket; against the wall of a calabash? However these wonderful painted Yang Shao pots were made, a thousand or so years later neighbors invented a method that hasn't been improved upon to the present day; the potters of Longshan, nearby inheritors of the Yang-shao tradition, formed their black pottery on a rapidly running potters wheel.

Water jug from the yellow River culture of prehistoric China. Coiled, beaten into shape, decorated with iron oxides and fired. 35,000 to 3,000 B.C.

The history of wheel thrown pottery is old. With the exception of the New World, wheels are found in fast or slow form almost everywhere. (Potters' wheels, as other functional wheels, were absent from the New World, until imported from The Old.) Wheels are kicked with the feet, by the potter or by an associate. In some places they are turned with a hand held stick, using a hole in the wheel head.

In developed countries, wheels are mechanically rotated using an electric motor.The variety of wheels is endless: standing, sitting, belt driven, foot driven, hand driven.

Centering - The potter has just pressed down on the rotating lump until it took on the symmetrical configuration called, "centered".

One "throws" pottery on the wheel. (From the Old English, thrawan, to cause to twist or to turn.) First the clay is worked to remove the air bubbles, then, literally, thrown onto the center of the wheel where it is "centered": shaped to be a radially symmetrical lump. When the beginning potter learns to center the clay so that it runs symmetrically through the hands, he is well on his way. Then, the potter "opens" up the mass, but not clear through to the bottom, unless he wants a bottomless pot. Now he has a spinning "doughnut" at the middle of a wheel head that rotates counter clockwise in the West, clockwise in the East. This he grasps with both hands at one side of the wheel and forces the turning torus to move out and become wider at his will.

When the clay is as wide as the potter wants it to be, with one hand inside and the other out, the potter moves his hands up the whirling wall, compressing as he goes, to raise the wall as high as he wishes. As those who have seen a skilled potter at work will attest, this raising of a clay wall is an apparently bewitched action. Three pulls to raise the wall, one to shape, and the work is done.

The ways of forming clay are many. Each culture, each country, develops its own technology. Most simply, clay coils are added one upon another until the pot is made. The shape need not be symmetrical; the forms can be started with sherds of bowls at the bottom to begin the construction. Seated, the Native American coils clay in her lap, the Nigerian walks backward around the pot, creating of herself a slow backwardly turning wheel.

In Pakistan soft clay is worked into the inside of molds made of biscuited (low fired) clay. Two halves are separately made, then pressed together. Chinese bottles were so made for a thousand years eliminating the trained thrower. With the invention of plaster as a molder of clay, and decals as the decorating mode, clay could be made to look like anything at all. Decoration of incredibly detailed design was repeated using decals; shapes were pressed over and over through the plaster, losing that variety that spoke of the potter's hand. Fastest and cheapest is slip casting. Toilets, porcelain dolls, sugar bowls, sewer pipes, figurines, low cost bonsai containers, all are now slip cast.

A tea-leaf container from nineteenth century Japan. The Shigaraki potter was in summer a farmer.

Little of the vitality of hand built or wheel thrown clay remains in the cast piece . The rough texture of the clay mix gives way to an unctuous surface impressed by the plaster. The finger ridges and irregularities of the hand nurtured, piece are replaced by artificial ridges designed to hide mold seams, by tapered sections that release easily from the mold. The irregularities of the dipped or poured glaze are replaced by the smoothness of air brush.

The virtue of the cast is identical replicates; thus stacking mugs, tessellating tile, ceramic spark plugs, and the economy of numbers. The implication of national rather than local distribution; the costs in energy, in conformity, are profound. The virtues of the cast are not those of the hand, where difference among similar replicates is cherished, where trails in the clay betray the potters method to the knowledgeable.

Mr. Chosan Watanabe, Japanese maker of coil and slab containers, raises a coil wall. Mr. Kan Komai, who translated for Mr. Watanabe, can be seen in the background.

Nine ten inch bowls slated to be altered into oval shapes. Here is an opportunity to observe the variations among a set of multiples. Although similar in height, thickness and general shape, each differs from the others, some more, some less. The potter was tolerant of small differences. Photographed in the author's studio.

The majority of our container needs were supplied in the past by potters at the wheel. There was no time for dainty finishing, for anything but the most quickly executed containers. Yet the work was all the better for its brusque honesty. As glass containers entered the American market, however, competition led the potteries to excess of decoration, but to no avail. The American container market born of the skills of immigrant potters lasted, in all, less than a hundred years before it gave way to the economies of poured glass.

China, the land of clay and coal, even today uses ceramic containers for many of their storage needs. Huge stoneware water containers stand before farm houses, their surfaces glazed with the loess of China's northeastern plains that contains its own flux: the ashes of how many thousand rice stubble burnings?

Even today many Chinese sauces and liquids are sold not in glass or aluminum, but in ceramic containers; green glazed earthenwares that haven't changed since the Tang dynasty; brown-black containers of red bean sauce.

The same was true in Japan until quite recently. Rural life depended upon clay containers for many necessities, water, grain and tea leaf storage, primary among them. Farmer-potters formed the necessary containers on the wheel. They used local clays, glazed inside or not, depending on the use, had their wares fired in communal kilns by traveling kiln experts. Shigaraki, Tamba, Tokoname; these are among the "Ancient Kilns" that are famous for their crude and honest, utilitarian stoneware. Even today in that Japanese Mecca of pottery cities, Kyoto, the old climbing kiln in the potters' section is filled with sewer pipe and art pottery, porcelain toilet bowls and priceless tea bowls.

In the nineteen twenties, Soetso Yanagi , founder of the Tokyo Crafts Museum, focused Japanese attention on the unpretentious beauty of functional peasant art. But Yanagi did not invent the twentieth century Japanese love of the unassuming, nor was respect for the functional previously unfamiliar to Japanese considerations. Long before, Tea Master, Sen No Rikyu (1521-1591) selected utensils for a Ceremony of Tea that he perfected for military dictator, Toyotomi Hideoshi. Rikyu chose unpretentious items of everyday use, thus raised them to the position of aesthetic elect. Under Rikyu's guidance, the Kyoto potter Chojiro developed the Raku technique as it is now known, characteristically unusual in its avoidance of self-conscious artistry. Rikyu and the Tea Ceremony (Cha - do , The Way of Tea) played a powerful role in the definition of a unique aesthetic for Japan, particularly as Tea focuses on other objects made of clay and other hand made utensils.

A Japanese tea bowl,"The Way of Tea", Cha-do, reveres the natural, the simple, the local. "Tea" defines a way of life, a national aesthetic.

One important change, some would say an epochal one, in the development of ceramic technology, was the discovery, during China's Tang Dynasty (618-907) of high fired ceramic. This was ware that rang clearer than the low fired "earthenware", ware that contained less of the iron flux in the clay, that was fired at a higher temperature, absorbing less water into the body. Above all, it was white, suitable for an emperor or a noble.

In China, Japan and Korea only "low fired and "high fired", translated as "pottery" (earthenware), and "porcelain " are identified by name. "Pottery" is low fired, generally red, absorbent, fragile to shock, but not to temperature. "Porcelain" is fired at about 2300oF, is brown, gray or white in color, quite sturdy to shock, but fragile to temperature.

Stacked against the wall at a porcelain factiory in Jing De Zhen, China, are thousands of "jiggered" plates. Each varies not a whit from the next.

In the West, we divide the high fired ware into "Stoneware" and "Porcelain". "Stoneware" contains some iron, is generally rough, and brown to gray in color, with low absorbency and a clear ring. "Porcelain" or "China" is made primarily from iron-free Kaolin (pure clay, originally from the village of Kaoling) fluxed with a feldspar. Porcelain is white, translucent when thin; rings clearly, and absorbs even less water than stoneware.

Kilns have been improved to make firing easier now than it was then. Electric and gas kilns, insulated with wonderful space age spun clay, regulated with gas and electric solenoids, populate the technologically appropriate pottery, large or small. But fire is fire, and heat is heat. The huge Gou-Yau (Old Kiln) of Jing De Zhen that fires large wood timbers in the basement of the kiln building, makes no less beautiful porcelain than do the controlled electric kilns of Rosenthal in Germany. Both operate in a tradition in which the epitome of beauty is recognized to have evolved in a wood fire, a thousand years ago, in Song Dynasty China.

The first glazes were developed some five thousand years ago in Egypt. There desert salts incorporated into a clay body migrated to the surface to form a glaze. Sodium and potassium will flux clay to form glaze, as sodium does in a salt kiln, and as the sodium and potassium laden wood ash fluxes clay in a wood kiln, or in ash glazes. When copper bearing minerals were additionally added, a bright blue or turquoise glaze resulted. eventually glazes were applied to the surface as we do today. Glazes are essentially glasses, but glasses with a very special quality. A fired clay object is substantially smaller than it was when it went into the glazing kiln. This is due to about six per cent shrinkage as the clay cools from its hottest temperature.

A good glaze forms a glass in the heat of the kiln, but a glass that expands as much as the clay body in the heat of the firing, and shrinks as much when the kiln cools; no more, no less. If the glaze shrinks less, then it stands off the body and shivers, if more, then the glaze develops small cracks, crackle, if they are desired, crazing if they are not.

The color of glazes comes from metallic salts. Few of these metal colorants can withstand the white heat of the stoneware kiln. Those that do, iron, cobalt, copper, nickel, are the classic colors of stoneware pottery, the colors of the stones of the earth. Add white, obtained with microscopic bubbles or the tin opacifiers of transparent glazes, and you have the potter's high temperature palette.

The ceramic art form is the only one I know in which the work, completed to the best of the artist's ability is risked in a transforming event, the firing. Between the conception and the completion, the crafter's skill intervenes. Between completion and realization, the firing intervenes, sometimes transforming the potters conception in ways of which he never dreamed. In the all but white heat of the firing, at 2300oF, those powdered glass formers, the glazes, take up colorants from the underlying clay, take up impurities and are influenced by them to local melting; glazes intermingle forming unexpected mixtures. Clay bodies melt and sag. The glazes, melting, pool in the low places in the clay surface, in ridges or intaglio lines. As the heat rises, glazes run, moving down the sides of pots, perhaps pooling in finger ridges, perhaps running off onto the kiln shelf. Of course, with safe glazes and controlled firings little happens that was not intended, but the greater the risk, the greater the magic. No wonder potters are such a crazy lot.

This pale greenish blue, crackled, stoneware bowl of the Northern Song Dynasty , early twelfth century, is about six inches in width. The bowl was designed to contain hot water, in which a small pitcher of spiced or sugared wine was kept warm. In Taiwan wine is served in that manner today. Elegant simplicity, solid color, thick glazes identify the stoneware of the Song.

The author critically eyes a recently shaped bonsai container in his Arlington, Washington, studio


After graduate study at the University of Illinois, Max Braverman spent 10 years as a Ph.D. biologist specializing in developmental research which ranged from molecular studies of chick eye lens development to computer oriented simulations of the development of the colonial hydroid, Podocoryne carnea. Then, in 1971, after a year's worth of night classes in wheel thrown pottery, he left the academic world to become a potter in Taos, New Mexico.

A subsequent visit to Japan influenced Max's perspective as a potter, in his words, "in a powerful and permanent manner." He was particularly struck by the beauty and simplicity of the common items of everyday Japanese life, articles "perfectly designed for their function" and "devoid of ostentation or self-conscious artiness."

After five years in Taos and ten in rural New Jersey --during which he met Chase Rosade and rekindled a long-held interest in bonsai--Max and his wife Kate Bowditch, who is an artist in her own right, moved once more. They now reside in a quiet mountain valley north of Seattle, Washington where Max's potting art is focused solely on the production of bonsai containers.

Recommended Books

1. Capon, Edmund. Art and Archeology in China; MacMillan Company of Australia Pty Ltd, 1977

2. Dickerson, John. Raku Handbook. van Nostrand, N.Y., 1977

3. Fujioka, Ryoichi, Tea Ceremony Utensil, Arts of Japan, 3 Weatherhill/Shibundo, N.Y., Tokyo, 1973.

4. Garnsey, Wanda with Rewi Alley, China Ancient kilns and modern ceramics. A guide to the potteries. Australian National University Press. 1983 5. Okakuro, Kazuzo. The Book of Tea, Dover Publications Inc., New York, 1964.

6. Rhodes, Daniel, Tamba Pottery, Kodansha Internatyional., 1982.

7. Rhodes, Daniel. Clay and Glazes for the Potter, 1957, Chilton, Phil.

8. Sanders, Herbet H. The World of Japanese Ceramics, Kodansha Int.., 1970.

9. Sato, Masahiko. Arts of Japan 2, Kyoto Ceramics, Weatherhill/Shibundo, N.Y., Tokyo, 1973.

10. Yanagi, Soetsu. The Unknown Craftsman, Kodamsha Int., 1972, Tokyo, San Francisco.

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