|
How The Ceramic Piece Is Produced?
In general, the Chinese definition for the porcelain covers a wide range of high-fired ceramics products. The Western definition may not recognized some of which as porcelain. Porcelain is usually green-fired (also known as once-fired). The body of the unfinished porcelain piece and the glaze applied are fired together in the high temperature kiln. After the body of a piece is fired for a long enough period of time, the porcelain piece is formed, finished and dried naturally. It is coated with the desired glaze, dried again and fired in the high temperature kiln. In the high temperature of the kiln, the body of the porcelain piece and the glaze are fused together to become a single piece or unit. The Chinese enamelled wares are also produced in this way. The exception is that the enamels are added after the first high-temperature firing. The pieces are then fired again in a second round but in a smaller, lower-temperature kiln.
Ceramic
The Chinese ceramics is a form of fine art developed since the early Chinese dynasty periods. China, in nature, has always been richly endowed with the raw earthen pottery materials needed for making ceramics. The first types of ceramics were made more than 11,000 years ago, during the Palaeolithic period. In the Chinese pottery tradition, it recognises only two main categories of ceramics i.e. high-fired [cí] and low-fired [táo] type of ceramics. The oldest Chinese definition for porcelain is "fine, compact pottery". In Western pottery tradition, ceramics are often classified into three primary categories i.e. stoneware, earthenware and porcelain. In the Western pottery context, the property of translucence is usually the defining feature of porcelain. Whereas, the Chinese pottery defined any opaque or thick piece that rings with a reasonably clear note on being struck as porcelain [cí].
Chinese ceramic wares are usually categorized into either southern or northern. China today comprises of two separate and geologically different land and regions. It was brought together by the action of natural continental drift and forming a junction that lies between the Huangher (Yellow River) and the Yangtze Jiang (Yangtze River). The contrasting geology of the south and north led to differences in the raw pottery making materials available for making ceramics.
Chinese porcelain is mainly made from the following two materials or a combination of the two. Both materials are derived from the weathering and decomposition of granite rocks.
• China clay, known as Gaoling in Chinese. It is composed mostly of the clay mineral kaolinite.
• Chinese porcelain stone, also known as petunse. It is a micaceous rock containing sericite and other minerals such as quartz.
Both are composed of platy minerals consisting of small platelets that ultimately allow the material to prevent the water to sieve through. Hence, it can retain and hold large amount of water. This is an important feature for making ceramics vessels that need to hold water or liquid.
History
In the Chinese ceramics context, the term of porcelain lacks a universally accepted definition. This in turn has led to the confusion about when the first Chinese porcelain was produced. Claims have been made for the late Eastern Han period (25 to 220 AD), the Three Kingdoms period (220 to 280 AD), the Period Of Disunion (265 to 589 AD), and the Tang Dynasty (618 to 907 AD). Fragments of pottery vessels found at the Xian Ren Dong (Fairy Cave), Wannian district in the province of Jiangxi, were dating from around the year 9000 BC show the evidence of the existence of the earliest known Chinese ceramics. The fragments wares were hand-made by coiling and fired in the bonfires. The decoration designs found on the wares include some impressed cord marks, and features produced by stamping and piercing.
The Xian Ren Dong site was occupied from about 9000 BC to about 4000 BC. During this period two common types of pottery were made. The first type was the coarse-bodied wares possibly made for daily use. The second type being finer and thinner-bodied wares possibly made for special occasions use. There are archaeological evidence showing that both types of wares were produced at the same period at some point.
Some experts believe the first true porcelain was made in the province of Zhejiang during the Eastern Han period. Chinese experts emphasize the presence of a significant proportion of porcelain-building minerals (china clay, porcelain stone or a combination of both) as an important factor in defining porcelain. Shards recovered from archaeological Eastern Han kiln sites estimated firing temperature ranged from 1260 to 1300°C. 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 the line between the two and true porcelain wares is not a clear one.
During the Sui (581-618) and Tang periods (618 to 907) a wide range of ceramics, low-fired and high-fired, were produced. These included the well-known Tang lead-glazed sancai (three-colour) wares, the high-firing, lime-glazed Yue celadon wares and low-fired wares from Changsha. In northern China, high-fired, translucent porcelains were made at kilns in the provinces of Henan and Hebei.
While the city of Jingdezhen has been an important production centre since the early Han Dynasty. In 1004 Jingde established the city as the main production hub for Imperial porcelain. During the Song and Yuan dynasties, porcelain made in the city and other southern China kiln sites used crushed and refined porcelain stones alone.
By the Ming dynasty the letters of Père Francois Xavier d'Entrecolles, a Jesuit missionary and industrial spy who lived in the city, described the manufacturing process. In his first letter dating 1712, d'Entrecolles described the way in which porcelain 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.
Though his first letter did not uncover any recipe secret to the Europeans in any timely fashion. In 1743, during the reign of the Qianlong Emperor, Tang Ying, the imperial supervisor in the city produced a memoir entitled "Twenty illustrations of the manufacture of porcelain." Unfortunately, the original illustrations have been lost, but the text of the memoir is still accessible.
Jingdezhen became the main production centre for large-scale porcelain exports to Europe starting with the reign of the Wanli emperor from 1573 to 1620.
By this time china clay and porcelain stone were mixed in about equal proportions. China clay produced wares of great strength when added to the body layer. Whiteness became a much sought after property, especially when combined to form blue-and-white wares. Porcelain stone was used with lower temperature of 1250°C in the region. Compared to those mixed with china clay, which required 1350°C. The large southern egg-shaped kiln varied greatly in temperature. Near the firebox it was hot. Near the chimney, at the opposite end of the kiln, it was cooler.
Chinese Porcelain Wares
Tang "Sancai" Burial Wares - "Sancai" means three-colours. However, the colours of the glazes used to decorate the wares of the Tang dynasty were not limited to three in number. In the West, Tang sancai wares were sometimes referred to as egg-and-spinach by dealers for the use of green, yellow and white. Though the latter of the two colours might be more properly described as amber and off-white / cream.
Sancai wares were northern wares made using white and buff-firing secondary kaolins and fire clays. At kiln sites located at Tongchuan, Neiqui county in Hebei and Gongxian 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. Burial wares, such as the well-known representations of camels and horses, were cast in sections, in moulds with the parts luted together using clay slip. In some cases, a degree of individuality was imparted to the assembled figurines by hand-carving.
Jian Tea Wares - Jian blackwares, mainly comprising tea wares, were made at kilns located in Jianyang of 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 1300°C. 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.
The hare's fur Jian tea bowl illustrated in the Metropolitan Museum of Art in New York. It was made during the Song dynasty (960 to 1279 AD) and exhibits the typical pooling, or thickening, of the glaze near the bottom. The hare's fur patterning in the glaze of this bowl resulted from the random effect of phase separation during early cooling in the kiln and is unique to this bowl. No two bowls have identical patterning. The bowl also has a dark brown iron-foot which is typical of this style. It would have been fired, probably with several thousand other other pieces, each in its own stackable saggar, in a single-firing in a large dragon kiln. One such kiln, built on the side of a steep hill, was almost 150 metres in length, though most Jian dragon kilns were fewer than 100 metres in length.
Jian tea wares of the Song dynasty were greatly appreciated and copied in Japan, where they were known as tenmoku wares. Phase separation in the iron-rich glazes of Chinese blackwares was also used to produce the well-known oil-spot, teadust and partridge-feather glaze effects.
Qingbai Wares - Qingbai wares 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 white". The qingbai glaze is a porcelain glaze, so-called because it was made using porcelain 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 (qingbai in Chinese means greenish-blue). 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 the year 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 porcelain stone instead of porcelain stone and china clay. The glaze and the body of the bowl would have been fired together, in a saggar, possibly in a large wood-burning dragon-kiln or climbing-kiln, typical of southern kilns in the period.
Though many Song and Yuan qingbai bowls were fired upside down in special segmented saggars, a technique first developed at the Ding kilns in Hebei province. The rims of such wares were left unglazed but were often bound with bands of silver, copper or lead.
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 Indonesian Belitung shipwreck ), but shards dating to the 8th or 9th century have been unearthed at Yangzhou in the 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 the province Zhejiang 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 the year 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, 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 porcelain body is finely textured, indicating the presence of a significant portion of china clay in the paste. 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 1350°C.
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.
Fakes And Reproductions
The Italian pottery of the mid-15th century shows heavy influences from Chinese ceramics. Chinese potters have a long tradition of borrowing design and decorative features from the earlier wares. Whilst ceramics with features thus borrowed might sometimes pose problems of provenance, they would not generally be regarded as either reproductions or fakes. However, fakes and reproductions have also been made at many times during the long history of Chinese ceramics and continue to be made today in ever-increasing numbers. The world today sees antiques as future investment because the values of the antiques are forever appreciate rather than depreciate.
• Reproductions of Song dynasty Longquan celadon wares were made at Jingdezhen in the early 18th century, but outright fakes were also made using special clay that were artificially aged by boiling in meat broth, refiring and storage in sewers. Père d'Entrecolles records that by this means the wares could be passed off as being hundreds of years old.
• At Jingdezhen the two remaining wood fired, egg-shaped kilns produce convincing reproductions of earlier wares. At Zhejiang province good reproductions of Song Longquan celedon wares continue to be made in large, side-stoked dragon kilns.
• Before the World War II, the English potter Bernard Leach found what he took to be genuine Song dynasty cizhou rice-bowls being sold for very little money on the dock of a Chinese port and was surprised to learn that they were in fact newly made.
• In modern times the market for Song dynasty Jian tea-bowls has been severely depressed by the appearance in large numbers of modern fakes good enough to deceive even expert collectors. It is reported that some of these fakes show evidence of having had genuine Song dynasty iron-foot bases grafted onto newly made bodies.
• In the late 19th century fakes of Kangxi period famille noire wares were made that were convincing enough to deceive the experts of the day. Many such pieces may still be seen in museums today, as may pieces of genuine Kangxi porcelain decorated in the late nineteenth century with famille noire enamels. A body of modern expert opinion holds that porcelain decorated with famille noire enamels was not made at all during the Kangxi period, though this view is disputed.
• A fashion for Kangxi period (1661 to 1722) blue and white wares grew to large proportions in Europe during the later years of the 19th century and triggered the production at Jingdezhen of large quantities of porcelain wares that strike a resemblance to ceramics of earlier periods. Such blue and white wares were not fakes or even convincing reproductions, even though some pieces carried four-character Kangxi reign-marks that continue to cause confusion to this day.
Authentication
There are various ways of authenticate the genuineness of an antique item. The most common method is human manual authentication and the scientific thermoluminescence (TL) test, which is used on some types of ceramic to roughly estimate the date of last firing of the antique piece. The TL test is carried out on small samples of porcelain drilled or cut from the body of a piece, which can be risky and disfiguring. It may cause a slight defect in the antique item and consequently affect the value of the antique item. For this reason, the test is rarely or seldom used for dating finely-potted and high-fired ceramics. The TL test is quite impossible to use on some types of porcelain items, particularly high-fired vitreous porcelain.
The most commonly used method is to authenticate by human. However, this method required a lot of subjects knowledge and experience. In order to be able to authenticate the antique item, one needs to have deep subjects knowledge on the history, design, pattern and experience in the subjects.
|
|
Antiquesstreets.com
Antiquesstreets.com
