Chinese ceramics show a continuous development since pre-dynastic times and are one of the most significant forms of Chinese art and ceramics globally. The first pottery was made during the Palaeolithic era. Chinese ceramics range from construction materials such as bricks and tiles, to hand-built pottery vessels fired in bonfires or kilns, to the sophisticated Chinese porcelain wares made for the imperial court and for export. Porcelain is so identified with China that it is still called “china” in everyday English usage.
Most later Chinese ceramics, even of the finest quality, were made on an industrial scale, thus few names of individual potters were recorded. Many of the most important kiln workshops were owned by or reserved for the Emperor, and large quantities of ceramics were exported as diplomatic gifts or for trade from an early date, initially to East Asia and the Islamic world, and then from around the 16th century to Europe. Chinese ceramics have had an enormous influence on other ceramic traditions in these areas.
Increasingly over their long history, Chinese ceramics can be classified between those made for the imperial court, either to use or distribute, those made for a discriminating Chinese market, and those for popular Chinese markets or for export. Some types of wares were also made only or mainly for special uses such as burial in tombs, or for use on altars.
Chinese porcelain is mainly made by a combination of the following materials:
Kaolin – essential ingredient composed largely of the clay mineral kaolinite.
Porcelain stone – decomposed micaceous or feldspar rocks, historically also known as petunse.
In the context of Chinese ceramics, the term porcelain lacks a universally accepted definition (see above). This in turn has led to confusion about when the first Chinese porcelain was made. Claims have been made for the late Eastern Han dynasty (100–200 AD), the Three Kingdoms period (220–280 AD), the Six Dynasties period (220–589 AD), and the Tang dynasty (618–906 AD).
Kiln technology has always been a key factor in the development of Chinese pottery. The Chinese developed effective kilns capable of firing at around 1,000 °C before 2000 BC. These were updraft kilns, often built below ground. Two main types of kiln were developed by about 200 AD and remained in use until modern times. These are the dragon kiln of hilly southern China, usually fuelled by wood, long and thin and running up a slope, and the horseshoe-shaped mantou kiln of the north Chinese plains, smaller and more compact. Both could reliably produce the temperatures of up to 1300 °C or more needed for porcelain. In the late Ming, the egg-shaped kiln or zhenyao was developed at Jingdezhen, but mainly used there. This was something of a compromise between the other types, and offered locations in the firing chamber with a range of firing conditions.
Important specific types of pottery, many coming from more than one period, are dealt with individually in sections lower down.
Pottery dating from 20,000 years ago was found at the Xianrendong Cave site, in Jiangxi province, making it among the earliest pottery yet found. Another reported find is from 17,000–18,000 years ago in the Yuchanyan Cave in southern China.
By the Middle and Late Neolithic (about 5000 to 1500 BCE) most of the larger archaeological cultures in China were settled farmers, who produced a variety of attractive and often large vessels, often boldly painted, or decorated by cutting or impressing. Decoration is abstract or stylized animals – fish are a speciality at the river settlement of Banpo. The distinctive Majiayao painted pottery, with orange bodies and black paint, is characterised by fine paste textures, thin walls, and polished surfaces; the almost complete lack of defects in excavated pots suggests a high level of quality control during production. The Majiayao and other phases of the Yangshao culture are well-represented in Western museums; by the Banshan phase purple was used in slip-painting alongside black. During the 4th millennium the potter’s wheel seems to scholars of Chinese ceramics to have been a Chinese invention, though several regions to the West also claim the honour. Previously coil-forming was used for large vessels.
Finds of vessels are mostly in burials, and sometimes hold the remains. By 4100–2600 BCE in the Dawenkou culture shapes later familiar from Chinese ritual bronzes begin to appear. One exceptional ritual site, Niuheliang in the far north, has produced numerous human figurines, some about half life-size.
Han dynasty, 206 BC – 220 AD
Some experts believe the first porcelain was made in Zhejiang province during the Eastern Han dynasty. Shards recovered from archaeological Eastern Han kiln sites estimated firing temperature ranged from 1,260 to 1,300 °C (2,300 to 2,370 °F). As far back as 1000 BC, the so-called “porcelaneous wares” or “proto-porcelain wares” were made using at least some kaolin fired at high temperatures. The dividing line between the two and true porcelain wares is not a clear one. Archaeological finds have pushed the dates to as early as the Han dynasty (206 BC – 220 AD).
The late Han years saw the early development of the peculiar art form of hunping, or “soul jar”: a funerary jar whose top was decorated by a sculptural composition. This type vessels became widespread during the following Jin dynasty (265–420) and the Six Dynasties.
The tomb figures that were to recur in the Tang were popular across society, but with more emphasis than later on model houses and farm animals. Green-glazed pottery, using lead-glazed earthenware in part of the later sancai formula, was used for some of these, though not for wares for use, as the raw lead made the glaze poisonous.
Sui and Tang dynasties, 581–907 AD
During the Sui and Tang dynasties (581 to 907 AD), a wide range of ceramics, low-fired and high-fired, were produced. These included the last significant fine earthenwares to be produced in China, mostly lead-glazed sancai (three-colour) wares. Many of the well-known lively Tang dynasty tomb figures, which were only made to be placed in elite tombs close to the capital in the north, are in sancai, while others are unpainted or were painted over a slip; the paint has now often fallen off. The sancai vessels too may have been mainly for tombs, which is where they are all found; the glaze was less toxic than in the Han, but perhaps still to be avoided for use at the dining table.
Liao, Song, Western Xia and Jin dynasties, 907–1276
The Song dynasty ruled the last parts of China to be controlled by ethnic “Han” Chinese before the Mongol invasion. It was culturally very advanced but militarily relatively weak. Artistic emphasis of Song pottery was on subtle glaze effects and graceful shapes. “What is clear is that in the Song Dynasty which tended to uphold the esthetics of conventional Confucianism, underglaze blue was not at all popular; Confucian esthetics emphasized simplicity, and the underglaze blue designs were judged to be too ornamental.”
Green ware or celadons were popular, both in China and in export markets, which became increasingly important during the period. Yue ware was succeeded by Northern Celadon and then in the south Longquan celadon. White and black wares were also important, especially in Cizhou ware, and there were polychrome types, but the finer types of ceramics, for the court and the literati, remained monochrome, relying on glaze effects and shape. A wide variety of styles evolved in various areas, and those that were successful were imitated in other areas. Important kiln sites and stoneware styles included Ru, Jun, Southern Song Guan or official ware, Jian and Jizhou. Whitish porcelain continued to be improved, and included the continuation of Ding ware and the arrival of the qingbai which would replace it.
The Liao, Xia and Jin were founded by non-literate, often nomadic people who conquered parts of China. Pottery production continued under their rule, but their own artistic traditions merged to some extent with the Chinese, producing characteristic new styles.
Yuan dynasty, 1271–1368
The Mongol Yuan dynasty enforced the movement of artists of all sorts around the Mongol Empire, which in ceramics brought a major stylistic and technical influence from the Islamic world in the form of blue and white porcelain, with underglaze painting in cobalt. This has been described as the “last great innovation in ceramic technology”. Decoration by underglaze painted patterns had long been a feature of Chinese pottery, especially in the popular Cizhou ware (mostly using black over slip), but was perhaps regarded as rather vulgar by the court and the literati class, and the finest ceramics were monochrome, using an understated aesthetic with perfect shapes and subtle glaze effects, often over shallow decoration carved or moulded into the surface.
This was a great contrast to the bright colours and complicated designs developed under the Yuan, whose organization was mostly based on Islamic art, especially metalwork, although the animal and vegetable motifs remained based on Chinese tradition. These were initially mainly made for export, but became acceptable at court, and to buyers of fine ceramics internally. Export markets readily accepted the style, which has continued to be produced ever since, both in China and around the world.
Ming dynasty, 1368–1644
The Ming dynasty saw an extraordinary period of innovation in ceramic manufacture. Kilns investigated new techniques in design and shapes, showing a predilection for colour and painted design, and an openness to foreign forms. The Yongle Emperor (1402–24) was especially curious about other countries (as evidenced by his support of the eunuch Zheng He’s extended exploration of the Indian Ocean), and enjoyed unusual shapes, many inspired by Islamic metalwork. During the Xuande period (1426–35), a technical refinement was introduced in the preparation of the cobalt used for underglaze blue decoration.
Prior to this the cobalt had been brilliant in colour, but with a tendency to bleed in firing; by adding manganese the colour was duller, but the line crisper. Xuande porcelain is now considered among the finest of all Ming output. Enamelled decoration (such as the one at left) was perfected under the Chenghua Emperor (1464–87), and greatly prized by later collectors. Indeed, by the late 16th century, Chenghua and Xuande era works – especially wine cups – had grown so much in popularity, that their prices nearly matched genuine antique wares of the Song dynasty or even older. This esteem for relatively recent ceramics excited much scorn on the part of literati scholars (such as Wen Zhenheng, Tu Long, and Gao Lian, who is cited below); these men fancied themselves arbiters of taste and found the painted aesthetic ‘vulgar.’
In addition to these decorative innovations, the late Ming dynasty underwent a dramatic shift towards a market economy, exporting porcelain around the world on an unprecedented scale. Thus aside from supplying porcelain for domestic use, the kilns at Jingdezhen became the main production centre for large-scale porcelain exports to Europe starting with the reign of the Wanli Emperor (1572–1620). By this time, kaolin and pottery stone were mixed in about equal proportions. Kaolin produced wares of great strength when added to the paste; it also enhanced the whiteness of the body—a trait that became a much sought after property, especially when form blue-and-white wares grew in popularity. Pottery stone could be fired at a lower temperature (1,250 °C; 2,280 °F) than paste mixed with kaolin, which required 1,350 °C (2,460 °F). These sorts of variations were important to keep in mind because the large southern egg-shaped kiln varied greatly in temperature. Near the firebox it was hottest; near the chimney, at the opposite end of the kiln, it was cooler.
Qing dynasty, 1644–1911
Primary source material on Qing dynasty porcelain is available from both foreign residents and domestic authors. Two letters written by Père François Xavier d’Entrecolles, a Jesuit missionary and industrial spy who lived and worked in Jingdezhen in the early 18th century, described in detail manufacturing of porcelain in the city. In his first letter dated 1712, d’Entrecolles described the way in which pottery stones were crushed, refined and formed into little white bricks, known in Chinese as petuntse. He then went on to describe the refining of china clay kaolin along with the developmental stages of glazing and firing. He explained his motives:
Types of Chinese pottery
Tang burial wares
Sancai means three-colours, green, yellow and a creamy white, all in lead-based glazes. In fact some other colours could be used, including cobalt blue. In the West, Tang sancai wares were sometimes referred to as egg-and-spinach.
Sancai wares were northern wares made using white and buff-firing secondary kaolins and fire clays. At kiln sites located at Tongchuan, Neiqiu County in Hebei and Gongyi in Henan, the clays used for burial wares were similar to those used by Tang potters. The burial wares were fired at a lower temperature than contemporaneous whitewares. Tang dynasty tomb figures, such as the well-known representations of camels and horses, were cast in sections, in moulds with the parts luted together using clay slip. They were either painted in sancai or merely coated in white slip, often with paint added over the glaze, which has now mostly been lost. In some cases, a degree of individuality was imparted to the assembled figurines by hand-carving.
Greenwares or celadon wares
The major group of celadon wares is named for its glaze, which uses iron oxide to give a broad spectrum of colours centred on a jade or olive green, but covering browns, cream and light blues. This is a similar range to that of jade, always the most prestigious material in Chinese art, and the broad resemblance accounts for much of the attractiveness of celadon to the Chinese. Celadons are plain or decorated in relief, which may be carved, inscribed or moulded. Sometimes taken by the imperial court, celadons had a more regular market with the scholarly and middle classes, and were also exported in enormous quantities. Important types are: Yue ware, Yaozhou ware and the wider Northern Celadons, Ru ware, Guan ware, and finally Longquan celadon.
Main article: Jian ware
Jian Zhan blackwares, mainly comprising tea wares, were made at kilns located in Jianyang, Fujian province. They reached the peak of their popularity during the Song dynasty. The wares were made using locally won, iron-rich clays and fired in an oxidising atmosphere at temperatures in the region of 1,300 °C (2,370 °F). The glaze was made using clay similar to that used for forming the body, except fluxed with wood-ash. At high temperatures the molten glaze separate to produce a pattern called “hare’s fur”. When Jian wares were set tilted for firing, drips run down the side, creating evidence of liquid glaze pooling.
Around the same time Jizhou ware developed with it “tortoiseshell” glaze effect.
Ding (Wade–Giles: Ting) ware was produced in Ding County, Hebei Province. Already in production when the Song emperors came to power in 940, Ding ware was the finest porcelain produced in northern China at the time, and was the first to enter the palace for official imperial use. Its paste is white, generally covered with an almost transparent glaze that dripped and collected in “tears”, (though some Ding ware was glazed a monochrome black or brown, white was the much more common type). Overall, the Ding aesthetic relied more on its elegant shape than ostentatious decoration; designs were understated, either incised or stamped into the clay prior to glazing. Due to the way the dishes were stacked in the kiln, the edged remained unglazed, and had to be rimmed in metal such as gold or silver when used as tableware. Some hundred years later, a Southern Song dynasty writer commented that it was this defect that led to its demise as favoured imperial ware. Since the Song government lost access to these northern kilns when they fled south, it has been argued that Qingbai ware (see below) was viewed as a replacement for Ding.
Like Ding ware, Ru ware (Wade–Giles : ju) was produced in North China for imperial use. The Ru kilns were near the Northern Song capital at Kaifeng. In similar fashion to Longquan celadons, Ru pieces have small amounts of iron oxide in their glaze that oxidize and turn greenish when fired in a reducing atmosphere. Ru wares range in colour—from nearly white to a deep robin’s egg—and often are covered with reddish-brown crackles. The crackles, or “crazing”, are caused when the glaze cools and contracts faster than the body, thus having to stretch and ultimately to split, (as seen in the detail at right; see also ). The art historian James Watt comments that the Song dynasty was the first period that viewed crazing as a merit rather than a defect. Moreover, as time went on, the bodies got thinner and thinner, while glazes got thicker, until by the end of the Southern Song the ‘green-glaze’ was thicker than the body, making it extremely ‘fleshy’ rather than ‘bony,’ to use the traditional analogy (see section on Guan ware, below). Too, the glaze tends to drip and pool slightly, leaving it thinner at the top, where the clay peeps through.
Jun (Wade–Giles : chün) ware was a third style of porcelain used at the Northern Song court. Characterized by a thicker body than Ding or Ru ware, Jun is covered with a turquoise and purple glaze, so thick and viscous looking that it almost seems to be melting off its substantial golden-brown body. Not only are Jun vessels more thickly potted, their shape is much more robust than the fine Jun pieces, yet both types were appreciated at the court of Emperor Huizong. Jun production was centered at Jun-tai in Yuzhou, Henan Province.
Main article: Guan ware
Guan (Wade–Giles : kuan) ware, literally means “official” ware; so certain Ru, Jun, and even Ding are Guan in the broad sense of being produced for the court. Usually the term in English only applies to that produced by an official, imperially run kiln, which did not start until the Southern Song dynasty fled from the advancing Jin dynasty and settled at Lin’an. It was during this period that walls become so thin and glaze so thick that the latter superseded the former in breadth. As the clay in the foothills around Lin’an, was a brownish colour, and the glaze so viscous.
Ge (Wade–Giles : ko), literally means ‘big-brother’ ware, because legend has it that of two brothers working in Longquan, one made the typical celadon style ceramics, but the elder made ge ware, produced in his private kiln. Ming dynasty commentator Gao Lian claims that the ge kiln took its clay from the same site as Guan ware, which is what accounts for the difficulty in distinguishing one from the other (though Gao thinks “Ge is distinctly inferior” to Guan). Overall, Ge remains somewhat elusive, but basically comprises two types—one with a ‘warm rice-yellow glaze and two sets of crackles, a more prominent set of darker colour interspersed with a finer set of reddish lines’ (called chin-ssu t’ieh-hsien or ‘golden floss and iron threads’, which can just faintly be detected on this bowl). The other Ge ware is much like Guan ware, with grayish glaze and one set of crackles. Once thought to have only been manufactured alongside Longquan celadon, per its legendary founding, Ge is now believed to have also been produced at Jingdezhen.
While similar to Guan ware, Ge typically has a grayish-blue glaze that is fully opaque with an almost matte finish. Its crackle pattern is exaggerated, often standing out in bold black. Though still shrouded in mystery, many specialists believe that Ge ware did not develop until the very late Southern Song dynasty or even the Yuan dynasty. In any case, enthusiasm for it persisted throughout the Ming dynasty; Wen Zhenheng preferred it to all other types of porcelain, in particular for brush washers and water droppers (although he preferred jade brush washers to porcelain, Guan and Ge were the best ceramic ones, especially if they have scalloped rims). Differences between later Ming imitations of Song/Yuan Ge include: Ming versions substitute a white porcelain body; they tend to be produced in a range of new shapes, for example those for the scholar’s studio; glazes tend to be thinner and more lustrous; and slip is applied to the rim and base to simulate the “brown mouth and iron foot” of Guan ware.
Qingbai wares (also called ‘yingqing’) were made at Jingdezhen and at many other southern kilns from the time of the Northern Song dynasty until they were eclipsed in the 14th century by underglaze-decorated blue and white wares. Qingbai in Chinese literally means “clear blue-white”. The qingbai glaze is a porcelain glaze, so-called because it was made using pottery stone. The qingbai glaze is clear, but contains iron in small amounts. When applied over a white porcelain body the glaze produces a greenish-blue colour that gives the glaze its name. Some have incised or moulded decorations.
The Song dynasty qingbai bowl illustrated was likely made at the Jingdezhen village of Hutian, which was also the site of the imperial kilns established in 1004. The bowl has incised decoration, possibly representing clouds or the reflection of clouds in the water. The body is white, translucent and has the texture of very-fine sugar, indicating that it was made using crushed and refined pottery stone instead of pottery stone and kaolin. The glaze and the body of the bowl would have been fired together, in a saggar in a large wood-burning dragon kiln, typical of southern kilns in the period.
The vase was made at Jingdezhen, probably around 1300 and was sent as a present to Pope Benedict XII by one of the last Yuan emperors of China, in 1338. The mounts referred to in the 1823 description were of enamelled silver-gilt and were added to the vase in Europe in 1381. An 18th-century water colour of the vase complete with its mounts exists, but the mounts themselves were removed and lost in the 19th century. The vase is now in the National Museum of Ireland. It is often held that qingbai wares were not subject to the higher standards and regulations of the other porcelain wares, since they were made for everyday use. They were mass-produced, and received little attention from scholars and antiquarians. The Fonthill Vase, given by a Chinese emperor to a pope, might appear to cast at least some doubt on this view.
Blue and white wares
Following in the tradition of earlier qingbai porcelains, blue and white wares are glazed using a transparent porcelain glaze. The blue decoration is painted onto the body of the porcelain before glazing, using very finely ground cobalt oxide mixed with water. After the decoration has been applied the pieces are glazed and fired.
It is believed that underglaze blue and white porcelain was first made in the Tang dynasty. Only three complete pieces of Tang blue and white porcelain are known to exist (in Singapore from the Indonesian Belitung shipwreck), but shards dating to the 8th or 9th century have been unearthed at Yangzhou in Jiangsu Province. It has been suggested that the shards originated from a kiln in the province of Henan. In 1957, excavations at the site of a pagoda in Zhejiang province uncovered a Northern Song bowl decorated with underglaze blue and further fragments have since been discovered at the same site. In 1970 a small fragment of a blue and white bowl, again dated to the 11th century, was also excavated in the province of Zhejiang.
In 1975, shards decorated with underglaze blue were excavated at a kiln site in Jiangxi and, in the same year, an underglaze blue and white urn was excavated from a tomb dated to 1319, in the province of Jiangsu. It is of interest to note that a Yuan funerary urn decorated with underglaze blue and underglaze red and dated 1338 is still in the Chinese taste, even though by this time the large-scale production of blue and white porcelain in the Yuan dynasty, Mongol taste had started its influence at Jingdezhen.
Starting early in the 14th century, blue and white porcelain rapidly became the main product of Jingdezhen, reaching the height of its technical excellence during the later years of the reign of the Kangxi Emperor and continuing in present times to be an important product of the city.
The tea caddy illustrated shows many of the characteristics of blue and white porcelain produced during the Kangxi period. The translucent body showing through the clear glaze is of great whiteness and the cobalt decoration, applied in many layers, has a fine blue hue. The decoration, a sage in a landscape of lakes and mountains with blazed rocks is typical of the period. The piece would have been fired in a saggar (a lidded ceramic box intended to protect the piece from kiln debris, smoke and cinders during firing) in a reducing atmosphere in a wood-burning egg-shaped kiln, at a temperature approaching 1,350 °C (2,460 °F).
Distinctive blue-and-white porcelain was exported to Japan where it is known as Tenkei blue-and-white ware or ko sometsukei. This ware is thought to have been especially ordered by tea masters for Japanese ceremony.
Blanc de Chine
Blanc de Chine is a type of white porcelain made at Dehua in Fujian province. It has been produced from the Ming dynasty (1368–1644) to the present day. Large quantities arrived in Europe as Chinese Export Porcelain in the early 18th century and it was copied at Meissen and elsewhere.
The area along the Fujian coast was traditionally one of the main ceramic exporting centers. Over 180 kiln sites have been identified extending in historical range from the Song dynasty to the present.
From the Ming dynasty, porcelain objects were manufactured that achieved a fusion of glaze and body traditionally referred to as “ivory white” and “milk white”. The special characteristic of Dehua porcelain is the very small amount of iron oxide in it, allowing it to be fired in an oxidising atmosphere to a warm white or pale ivory colour. (Wood, 2007)
The porcelain body is not very plastic but vessel forms have been made from it. Donnelly, (1969, pp.xi-xii) lists the following types of product: figures, boxes, vases and jars, cups and bowls, fishes, lamps, cup-stands, censers and flowerpots, animals, brush holders, wine and teapots, Buddhist and Taoist figures, secular figures and puppets. There was a large output of figures, especially religious figures, e.g. Guanyin, Maitreya, Lohan and Ta-mo figures.
The numerous Dehua porcelain factories today make figures and tableware in modern styles. During the Cultural Revolution “Dehua artisans applied their very best skills to produce immaculate statuettes of Mao Zedong and the Communist leaders. Portraits of the stars of the new proletarian opera in their most famous roles were produced on a truly massive scale.” Mao Zedong figures later fell out of favour but have been revived for foreign collectors.
Notable artists in blanc de Chine, such as the late Ming period He Chaozong, signed their creations with their seals. Wares include crisply modeled figures, cups, bowls and joss stick-holders.
Many of the best examples of blanc de Chine are found in Japan where the white variety was termed hakugorai or “Korean white”, a term often found in tea ceremony circles. The British Museum in London has a large number of blanc de Chine pieces, having received as a gift in 1980 the entire collection of P.J.Donnelly.
Classification by colour, the “Famille” groups
Commonly used French terms for ‘families’, or palettes of enamel colours used on Chinese porcelain. Famille jaune, noire, rose, verte are terms used to classify Chinese porcelain by the dominant element in its colour palette.
Famille verte (康熙五彩, Kangxi wucai, also 素三彩, Susancai), adopted in the Kangxi period (1662–1722), uses green and iron red with other overglaze colours. It developed from the Wucai (五彩, “Five colours”) style.
Famille jaune is a variation using famille verte enamels on a yellow ground. Famille noire (Chinese: 黑地素三彩, Modi susancai) uses a black ground (although some clobbered wares had the black added in the 19th century).
Famille rose (known in Chinese as Fencai (粉彩) or Ruancai (軟彩, simplified 软彩), meaning ‘soft colours’, and later as Yangcai (洋彩), meaning ‘foreign colours’) was introduced during the reign of the Kangxi Emperor (1654–1722), possibly around 1720. It used mainly pink or purple and remained popular throughout the 18th and the 19th centuries, also being widely adopted by European factories.
Famille rose enamel ware allows a greater range of colour and tone than was previously possible, enabling the depiction of more complex images, including flowers, figures and insects.
Pottery classified as stoneware in the West is usually regarded as porcelain in Chinese terms, where a stoneware group is not recognised, and so the definition of porcelain is rather different, covering all vitrified high-fired wares. Terms such as “porcellaneous” and “near-porcelain” are often used to reflect this, and cover wares that in Western terms lie on the border of stoneware and porcelain. High-fired stonewares were numerous from very early on, and included many high-prestige wares, including those for imperial use, as well as great quantities of everyday utilitarian pots. Usually they achieved their reputation by their glazes. Most of the celadon group, including Longquan celadons, especially earlier ones, can be classified as stoneware, and all classic Jian wares and Jizhou wares.
By contrast, the Yixing clay teapots and cups made from Yixing clay from Jiangsu province are usually left unglazed, and not washed after use, as the clay is believed to improve the taste of the tea, especially after it acquires a patina from long use. There are in fact a number of different clays, giving a range of colours. The pots are unusual in that they are often signed by their potters, which is very rare in China, perhaps because they were associated with the literati culture, of which Jiangsu was a stronghold. The earliest datable example is from a burial of 1533 in Nanjing. Elaborately decorated examples, often with a rectangular body, were exported to Europe from the 18th century, and these and pots for local use often had poems inscribed on them. As well as teaware and desk objects such as brush-rests, fruit and other natural shapes were modelled as ornaments. Production continues today, generally using simpler shapes.
Source from Wikipedia