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Defintion & descriptionEditar
One widely recognized definition is from the Combined Nomenclature of the European Communities, which states:
"Stoneware, which, though dense, impermeable and hard enough to resist scratching by a steel point, differs from porcelain because it is more opaque, and normally only partially vitrified. It may be vitreous or semi-vitreous. It is usually coloured grey or brownish because of impurities in the clay used for its manufacture, and is normally glazed."
Due to its high strength and durabilty stoneware has a wide range of uses, including: hotelware, kitchenware, cookware, garden products, electrical, chemical and laboratory ware. Formulations vary considerably, although the vast majority will conform to: plastic fire clays 0 - 100% , ball clays 0 - 15%, quartz, 0 - 30% feldspar and chamotte 0 - 15%
Stoneware is generally once fired. Maximum firing temperatures can vary significantly, from 1100°C to 1300°C depending on the flux content. More typically temperatures will be between 1180°C to 1280°C, the higher end of which equate to Bullers Rings 38 to 40 & Seger cones 4 to 8. To produce a better quality fired glaze finish twice firing can be used, and this can be especially important for formulations composed of highly carbonaceous clays. For these, biscuit firing is around 900°C and glost firing 1180 - 1280°C. Water absorption of stoneware products is less than 1%.
Five categories have been suggested:
- Traditional stoneware - a dense and inexpensive body. It is opaque, can be of any colour and breaks with a conchoidal or stony fracture. Traditionally made of fine-grained secondary, plastic clays which can used to shape very large pieces.
- Fine stoneware - made from more carefully selected, prepared and blended raw materials. It is used to produce tableware and art ware.
- Chemical stoneware - used in the chemical industry, and elsewhere when resistance to chemical attack is needed. Purer raw materials are used than for other stoneware bodies. Ali Baba is a popular name for a large chemical stoneware jars of up to 5000 litres capacity used to store acids.
- Thermal shock resistant stoneware – has additions of certain materials to enhance the thermal shock resistance of the fired body.
- Electrical stoneware - historically has been used for electrical insulators, although has been replaced by electrical porcelain.
Another type, Flintless Stoneware, has also been identified. It is defined in the UK Pottery (Health and Welfare) Special Regulations of 1950 as: "Stoneware, the body of which consists of natural clay to which no flint or quartz or other form of free silica has been added."
History and notable examplesEditar
The earliest example of stoneware is found in China, naturally as an extension of higher temperatures achieved from early development of reduction firing. From the various definitions of high-fired ceramics, it is agreed that the earliest stoneware is encountered in the late Shang dynasty in China, with large quantities in production by the Han dynasty.
Other notable historical examples include:
- American Stoneware refers to the predominant houseware of nineteenth century North America.
- Bartmann jug - a type of decorated stoneware that was manufactured in Europe throughout the 16th and 17th centuries, especially in the Cologne region of Germany.
- Böttger Ware - a dark red stoneware developed by Johann Friedrich Böttger. It is a very significant stage in the development of porcelain in Europe.
- Cane Ware - eighteenth-century English stoneware of a light brown colour; it was a considerable advance on the coarse pottery that preceded it but, for use as tableware, cane ware was soon displaced by white earthenware. During the 19th and the earlier part of the 20th century, however, cane ware continued to be made in South Derbyshire and the Burton-on-Trent area as kitchen-ware and sanitary-ware; it had a fine-textured cane-coloured body with a white engobe on the inner surface often referred to as cane and white.
- Crouch Ware - light-coloured Staffordshire salt-glazed stoneware of the early 18th century. It is credited as being one of the earliest examples of stoneware made in England. It was made from a clay from Crich, Derbyshire, the word `crouch' being a corruption.
- Rosso Antico - a red unglazed stoneware made in England during the 18th century by Josiah Wedgwood, and was a refinement of the red ware previously made in North Staffordshire by the Elers.
- ↑ Standard Terminology Of Ceramic Whiteware and Related Products. ASTM Standard C242.
- ↑ 2,0 2,1 2,2 2,3 Dictionary Of Ceramics. Arthur Dodd & David Murfin. 3rd edition. The Institute Of Minerals. 1994.
- ↑ E-Learning item - Body Compositions. Ceram Research.
- ↑ An Introduction To The Technology Of Pottery. Rado P. Pergamon Press, 1988
- ↑ Whitewares: Production, Testing And Quality Control. W.Ryan & C.Radford. Pergamon Press / Insitute Of Ceramics, 1987
- ↑ 'E-Learning item - Body Compositions'. Ceram Research.
- ↑ Industrial Ceramics. Singer F., Singer S.S. Chapman Hall 1963
- ↑ Dictionary Of Ceramics. Arthur Dodd & David Murfin. 3rd edition. The Institute Of Minerals. 1994.
- ↑ Sato, Masahiko. Chinese Ceramics: A Short History (1st edition). John Weatherhill, Inc. (1981), p.15.
- ↑ Li, He. Chinese Ceramics: A New Comprehensive Survey. Rizzoli International Publications, Inc. New York, New York (1996), p. 39.
- ↑ Rhodes, Daniel. Stoneware and Porcelain: The Art of High-Fired Pottery. Chilton Co., Philadelphia, Pennsylvania (1959), p.7.
- ↑ Ibid., p. 8.
- ↑ The Discovery Of European Porcelain By Bottger - A Systematic Creative Development. W. Schule, W. Goder. Keram. Z. 34, (10), 598, 1982
- ↑ 300th Anniversary. Johann Friedrich Bottger - The Inventor Of European Porcelain. Interceram 31, (1), 15, 1982
- ↑ Invention Of European Porcelain. M. Mields. Sprechsaal 115, (1), 64, 1982
- ↑ http://www.wedgwood.com/GB/About_Wedgwood/_Design_and_Craftsmanship/Heritage_Products/Heritage_Products_Page_3
- ↑ http://www.wedgwoodsocalif.org/caneware.html
- ↑ Salt glazed stoneware. E.A.Barber. Hodder & Stoughton, 1907
- ↑ http://www.encyclo.co.uk/define/crouch%20ware
- ↑ http://www.wedgwood.com/GB/About_Wedgwood/_Design_and_Craftsmanship/Heritage_Products/Heritage_Products_Page_4
- ↑ Wedgwood and his imitators. N.H.Moore. Frederick A. Stokes Company, 1909.
- Combined Nomenclature of the European Communities - EC Commission in Luxembourg, 1987
- Beardman jugs from the Avondster site -- Provides photographs and history of early Rhenish stoneware vessels, produced circa 1500s-1700s.
- Japanese stoneware in the collection of the Asia Society.