Recognized by artisans and literati centuries ago, these characteristics of the Zisha or purple clays help to make Yixing pots especially well-suited for brewing tea. Excavations have shown that the composition and structure of the clays used in making authentic Yixing teapots today closely resemble those used in pots from the 1500s and later.Yixing Teapots are made by a very special unglazed clay material called “zisha” clay. The yixing purple clay teapot is reputed as the “first of all tea-sets in the world” for its unique material and characteristics.
Yixing clay has very special characteristics chemistry composition and texture, a 4% 0f the water absorption rate, a very low thermal conductivity, and other
unique qualities, it already is confirmed and is received that Yixing clay is best raw materials for made teapot in whole world. When properly refined and fired to a high (but sub-porcelain)
temperature, it produces a type of pottery that is slightly absorbent. Legend has it that if you have prepared tea in an Yixing teapot many times, you can reach a point where by adding boiled
water alone you can make tea, because the teapot itself holds enough of the tea flavor.
The characteristics of yixing teapot
Pottery made from purple clay is earthy and refined, and displays the ingenuity of the craftsman; it is full of cultural flavor characteristic of the East. The ancients praised that “pearls and jade can be found everywhere but there is only one soil like that at Yangxian(Yixing) Shitzu.” Therefore, one can say that purple clay soil is a national treasure endowed by the heavens.
The ancients praised tea drinking thus: “water is the mother of tea and teapot is the father” and “Yixing clay teapots are the best”:
1. One of the special attributes of Yixing teapot is the ability to retain heat. Mixing clay teapots conduct heat slower so can hold the heat longer, and it doesn’t burn the hand if you touch it.
2.Small pores produced in the clay during firing retain both heat and flavor, the lid keeps the steam in and yet does not smother the aroma, and the low shrinkage rate of Yixing clay allows the skillful potter to make a closely-fitting lid that inhibits oxidation thus heightening the tea flavor.
Mixing teapot can keep tea’s heat, primary color, aroma and taste. This is proved by the test: the fine qualities of tea will been retain for 5 days if you use fixing teapot. But it only can retain 3 days if you using other ceramics teapots.
3. The Yixing teapot is free of lead, arsenic, cadmium, and other toxic materials. Mixing ware is unlike other unglazed earthenware teapots. The Yixing teapot has a fine and solid texture, a four percent water absorption rate, a very low thermal conductivity, and a double air pore striation which enhances the pot brewing properties. The principal standards for evaluating a teapot brewing quality are the color of the tea soup produced and the level of tea phenol, caffeine, and aminophylline. The performance of the Yixing teapot is far superior to that of the standard teapot with respect to all four of these criteria. Not only are the Yixing teapots beautiful and unique works of art, but also, they are excellent brewing vessels. in fact,mixing teapots exceeds the strict standards imposed by china’s pottery research institute and are also approved by the use”fad”.to ensure this high standard of quality.
4. Tea inside it does not seep though no glaze is applied on its surface, tea brewed in it tastes rich and mellow for the Yixing teapot is porous. After firing, Yixing tea pot is solid and impermeable, yet porous enough to “breathe”. A Yixing teapot enhances the tea brewed in it with respect to color, smell, and taste. Its walls seem to absorb the tea and keeps fragrance. In summer, it keeps tea overnight without spoiling. With hot tea inside, it does not scald the hand with purple sand being a slow heat-conductor. But in winter, it may serve as a hand warmer and may be left on a low fire to make certain types of tea which need simmering. To the Chinese tea connoisseur, it is the “ideal teapot”.
5. Purple clay pottery is like wool: thick, snug, neat, pure, classy; and it is luminous as a piece of antique jade. Because the mixing teapot’s surface is fine and delicate, the more you use it, the shinier it becomes, the newer it looks, and the more energy it seems to exude. The colors of the clay are rich and varied, smooth and elegant, earthy and stable.
6. Because of its special composition, purple clay is also good for making flower pots since it can let light through and absorb water, which prevent roots from rotting.
Mixing teapot each piece is shaped by hand on a potter wheel and left unglazed, both because it makes better tea and because doing so allows the color of the clay to shine through. Highly prized for its porous nature, which is excellent at absorbing the flavor of tea, Purple sand or clay does not really in purple color only, it depends on the layering from the ground, different layers has different color, Yixing clay occurs naturally in the characteristic colors: light buff, cinnabar red and purplish brown. It can have many natural color after fired.
Yixing clay variety and basic info
Clay of Yixing are mainly Jiani, Nenni and Baini.
Jiang is dark solid clay mostly used for making ceramics, vase etc..Nenni is yellowish soft clay. Bain is white clay that is mainly kaolinite, used to make porcelain or ceramic. But the real clay used to make fixing teapot is zisha, there are actually three different varieties of Zisha.
The most common of these are the Zini or purple(rose-brown) clays. The other two more rare clays are know asBanshanlu(light green) or creamy white to light-brown clays and Zuni or red clays. Chemically, all are composed primarily of quartz, kaolin and mica and contain high amounts of iron oxide, which lends the clays their purple-red color. Zisha clays are also fairly sandy. All are from local mines and are composed of natural minerals. They are hidden between rocks and ordinary pottery soil, that is why they are sometimes called the “soil within the rock” and the “soil within the soil.”
The three soils are mixed according to need and the color desired. Then, it is fired at various temperatures depending on the soil composition.
• Darker colored clay is more rich but the color gradations range from: sky green, millet, deep purple, pear skin, cinnabar purple, flowering apple red, green gray, ink green, to bluish black, etc.
• There are colors that can be described as: modest purple, delicate red, mature green, chromatic black, and florid gray, etc., that are truly elegant.
• Other colors are created by mixing these three clay.
• A principal factor in determining the depth of the color is the concentration of iron in the clay.
Mini (purple, fired is usually brownish) exists as small amount inside Jiani ore bed.
When Zini contains so much manganese that becomes dark dots after firing, it’s called Hei Xing ni(aka Tie Xing ni, Hei Xing Sha).
Qing Shui ni originally is about method of clay manufacturing, pure clay without any mixing, usually mined from mid part of ore bed, common clay.
Di Cao Qing is from deep inside, usually reddish brown. Di Cao Qing is usually darker and heavier than Qing Shui ni.
Pin Zini means mixed Zini.
Luna (aka Ben Shan Lu ni, Benshan means original mountain that is Mt. Huanglong) is sort of mutant silica dots, evenly found from Jiani ore bed, very rare.
Duane is also rare, coincidently when co-exists with Luni and Zini. Most Duanni today however, is from Tanxi or Hufu or intentionally mixed with Luni and Zini.Zima(sesame) Duanni has many dark dots that resembles sesame. Bad Ma Zi ni is very similar to Luni after firing but not smooth and lots of grits.
Honing is from Nenni ore bed.
Zuni is very yellow ore, more yellow, better Zuni. On Zuni, is special clay cos it has different characteristics than other clay. Unlike other clay(Huang Long mountain), birth place of Zuni is Zhao Zhuang mountain, which is Lao Zuni. Most of Zuni today is from Xiao Mei Yao (near Huang Long mt.) and Hu Fu (aka modern Zuni).
Xiao Hongni is darker than yellow.
Da Hongni is from Jiani ore bed, basically Zini.
Da Hong Pao ni was from Huang Long mt., very popular during Qing dynasty. Real Da Hong Pao ni however, would sell no less than 500 USD. Most of DHP ni is from Fudong area recently.
On Pin Pei (mixing clay)
Pin Pei can be classified as clay-mixing and chemical ingredient-mixing. On former one, can actually enhance the quality of clay and plasticity.
Great masters such as Si Da Bin or Hui Meng Chen were actually masters of Bing Pei.
For example, the most expensive clay like Ben Shan Luni can’t be used for teapot making without mixing with Zini, unless it’s used for decoration.
The sought-after clay like Di Cao Qing, is actually better in smoothness and color after mixing with Qing Shui ni or Zini. Pure Di Cao Qing not only requires high temperature (1240C) to be
fired but also unglossy and dark. However, Zuni is exception.
Latter is mixing with ingredients such as manganese oxide, iron oxide, copper oxide etc..
It looks good when first exhibition, but doesn’t earn natural patina after long time of usage.
Also, these clays are actually fired at low temperature and smell a lot.
The characteristics of the yixing clay may be summed up into following aspects:
The plasticity of ready clay, the hardness of the shaped clay-body and the low contraction rate make it possible to create pottery of various kinds, fantastic designs and different lines. For hundreds and thousands of years, generations of artists have kept on experimenting and exploring and added splendor to the civilization of mankind.
1.Of high plasticity. With a liquid limit of 33.4%, modeling limit of 15.9% and an index of 17.5%, purple-clay is of high plasticity and can be made into various shapes of different sizes. It has strong adhesion, but is not glutinous in hands and implements. The mouth, handle and the teapot body can be made separately before they are stuck together and polished with clay. The clay pieces of square vessels may be got together with grease clay, too. Such a large capacity materially enables the pottery artists to fully display their creative intention and give free play to their artistic techniques.
2.Of low contraction rate. From a clay base to a fired product, its contraction rate is only about 8%. It also has a wide range of firing temperature, a low deformation rate and a strong intensity of the raw chaybase. So the teapot cover suits the mouth very tightly, the contour is up to standard and can not be twisted. The handle may be designed thicker than that of a porcelain pot, and the round surface of the pot mouth is in proportion with the mouth. Besides, the clay can be used to make open-mouth vessels and teapots with mouth and body of the same width.
3.Purple-clay can be processed into pottery without any addition of other materials. The produced pottery have two layers of gas hole construction: close-mouth layer, that is the gas hole inside the nodule body; and open-mouth layer, which refers to the gas hole group around the nodule body. The two layers of gas hole provide the purple-clay pottery with fine ventilation. In addition, the tiny gas holes of high density possess strong absorption, which the glazed ceramic teapot lacks. Meantime, precisely and reasonably shaped, the mixing teapot, with its mouth and cover fitting perfectly, has a displacement error within a tolerance of less than 0.5mm, which decreases the possibility of the air mixed with germs entering into the pot. Therefore, the color and flavor and fragrance of tea may last for quite a long time and delay the time when the tea goes bad. Furthermore, purple-clay teapot has the capacity to tolerate sudden heat and coldness. Even if boiling water and cold water are alternately poured into it, it will not explode or crack.
4.Another uniqueness of purple-clay is that it needn’t be glazed after it is shaped. It is smooth and shiny. After it is handled and caressed for a long time. It
will send out dim light. While pottery clay of other texture can not be compared to it in this aspect.
Full hand Yixing teapot making process
Besides the exceptional structure and mineral composition of Yixing clay, the most unique characteristic about the Yixing teapot is the traditional coiling technique of “forging the body” that is used to make a Yixing teapot. Unlike the common “earth clay” which comes in the form of “mud,” the raw Yixing clay comes in the form of rock, and it only appears to be like “mud” after many steps of preparing and refining. For this very reason the true Yixing clay cannot be turned on a pottery wheel. The modeling methods of Yixing clay pottery, since the Zhengde period in Ming Dynasty, have been becoming more and more perfect, owing to generations of Yixing artists’ exploration and improvement as well as the progress of science and technology.
The true Yixing clay can only be manipulated in the following three ways: half-hand building, full-hand building and casting&molding. There are various detailed methods which may be summarized into: hand forming, injecting mud forming, applying base forming and printing, etc.. They are an ancient craft, includes beating pot body and inlaying pot body.
Slab building and half-mold pressing are two major methods. They produce Yixing teapots with intact original Yixing clay characteristics. Of the two approaches, building a pot from a slab, the
most traditional way of doing it, is the most highly regarded in teapot making, in terms of both the craft and the market demand.
While the concept of slab building in ceramics is deceptively simple, making a fine Yixing pot takes great skills. The artist has to maintain clay consistency and finishes. Any blemishes will not be covered, with glazes or roughness in treatment in the name of spontaneousness. Do note that the parts have to fit and work together with balance, smoothness and uniformity. Clay shrinks quite dramatically (usually 12 ~ 20%, depending on the formula and firing).The kind of precision these artists can achieve manually simply for a pot with aligned spout and handle and a fitting lid is in itself amazing, let alone elegance and precision in form and styling. Most practicing artists have begun working with clay since teenage, some even younger.
Hand-build Yixing teapots are made by the traditional coiling technique of “forging the body,” which was invented by Shi Dabin from the Ming dynasty according to the Zisha history:
1. After raw Zisha clay was being prepared into curbed “mud,” the artist begins to beat and forge the “Zisha mud” with a wooden bat.
2. After the forging process, the “Zisha mud” is rolled into a thin and long strip, and cut into the sizes needed and then pinched together to form the basic shape of the body of a vessel.
3. Subsequently the artist continues to beat and forge the “body” with the wooded paddle until the “body” is precisely formed into the desired shape.
4. Beating Yixing teapot body forming: First cut the ready clay into pieces in a certain length, width and thickness. Then beat them into clay slices and strips according to the vessel being made. Make scratches on the clay to show the width and whirl the mouth, bottom and body pieces. Stick the body pieces in the center of the revolving plate, and put the clay piece around the body pieces to form a clay tube. Then the left hand inside the round tube, use the right hand, with a thin wood beater, to beat it into desired shape.
5. The next step is to build the various parts of the teapots individually.
6. Then the finished “body” and the parts are assembled together, and carefully adjusted and polished before firing.