Science Fair Project Encyclopedia
Porcelain is a type of hard semi-translucent ceramic generally fired at a higher temperature than glazed earthenware, or stoneware pottery. It is white, but mildly translucent and can be decorated to provide colour.
Chinese porcelain is made from a hard paste comprised of the clay kaolin and a feldspar called petuntse, which cements the vessel and seals any pores. China is high-quality porcelain. Most china comes from the city of Jingdezhen in China's Jiangxi province.
Jingdezhen, under a variety of names, has been central to porcelain production in China since at least the early Han Dynasty. Earliest techniques were very primitive, barely above the level of standard pottery. By the time of the Southern and Northern Dynasty period, however, techniques and materials had been improved to the point that Jingdezhen clay was refined into porcelain.
The Sui and Tang Dynasties introduced high-temperature kilns, resulting in pure, translucent whites, attractive to the eye, as well as a variety of advanced glazing techniques. These improvements produced smooth, durable porcelain ware. The resulting product was often referred to as "false jade".
The most noticeable difference between porcelain and the other pottery clays is that it 'wets' very quickly (that is, added water has a noticeably greater effect on the plasticity for porcelain than other clays), and that it tends to continue to 'move' for longer than other clays, requiring experience in handling to attain optimum results.
Porcelain clays can be chemically formulated for strength, plasticity and durability to the point that they can be used as throwing bodies. Porcelain ware was produced on the potter's wheel in many historic cultures, including China and Japan. Many categories of glazes, e.g. celedons, were formulated specifically for their striking effects on porcelain. Modern potters also produce porcelain ware, and generally believe these clay bodies challenge production, firing and glazing skills. Commercially formulated procelain bodies are generally available through most clay distributers.
The European porcelain was invented in Dresden and Meissen (Germany), under the rule of King August the Strong (1694-1733). There is also the biggest porcelain collection of the world. In a period when the Chinese and Japanese held the secret how to produce porcelain, August the Strong set out to discover the hidden process. For over 200 years Europeans had unsuccessfully played alchemist to the Japanese and Chinese porcelain masters, until Johann Friedrich Böttger unearthed the recipe to cure August of his mad obsession with white gold.
The Europeans used a soft paste, which makes for weaker porcelain than the Chinese method. To compensate, around 1750 the English began to use calcined bone ash to strengthen their porcelain, with the resulting material (typically comprising 25% to 50% bone ash) becoming known as bone china .
Key people and places
- Gshel , Russia
- Josiah Wedgwood
- Limoges, France
- Meißen, Germany
- Pécs, Hungary
- Porsgrunn, Norway
- Sèvres, France
- Worcester, England
- Delft, Netherlands
- Chinese porcelain at the Lady Lever Art Gallery
- Jingdezhen attractions
- Jingdezhen: Ceramics Metropolis of China
- Jingdezhen Special Folk Arts Porcelain Research Institute
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