Stoneware

A Staffordshire stoneware plate from the 1850s with transferred copper print (From the home of J. L. Runeberg)

Stoneware is a vitreous or semi-vitreous ceramic made primarily from stoneware clay or non-refractory fire clay.[1] Stoneware is fired at high temperatures.[2] Vitrified or not, it is nonporous;[3] it may or may not be glazed.[4]

Definition and description

A handpainted stoneware bowl produced in Portugal in 2008
A Chinese stoneware vase from the Song Dynasty, 11th century

One widely recognised definition is from the Combined Nomenclature of the European Communities, a European industry standard. It 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."[3]

The key raw material in stoneware is either naturally occurring stoneware clay or non-refractory fire clay. The mineral kaolinite is present but disordered, and although mica and quartz are present their particle size is very small. Stoneware clay is often accompanied by impurities such as iron or carbon, giving it a "dirty" look, and its plasticity can vary widely.[5] Non-refractory fire clay may be another key raw material. Fire clays are generally considered refractory, because they withstand very high temperatures before melting or crumbling. Refractory fire clays have a high concentration of kaolinite, with lesser amounts of mica and quartz. Non-refractory fire clays, however, have larger amounts of mica and feldspar.[6]

Formulations for stoneware vary considerably, although the vast majority will conform to: plastic fire clays, 0 to 100 percent; ball clays, 0 to 15 percent; quartz, 0 to 30 percent; feldspar and chamotte, 0 to 15 percent.[7]

Stoneware can be once-fired or twice-fired. Maximum firing temperatures can vary significantly, from 1100 °C to 1300 °C depending on the flux content.[8] Typically, temperatures will be between 1180 °C to 1280 °C, the higher end of which equate to Bullers Rings 38 to 40 or Seger cones 4 to 8. To produce a better quality fired glaze finish, twice-firing can be used. This can be especially important for formulations composed of highly carbonaceous clays. For these, biscuit firing is around 900 °C, and glost firing (the firing used to form the glaze over the ware) 11801280 °C. Water absorption of stoneware products is less than 1 percent.[9]

Six categories of stoneware have been suggested:[10]

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."[12]

History and notable examples

The earliest examples of stoneware have been dated to 1900 BCE in the Indus Valley Civilization.[13] An industry of a nearly industrial-scale mass-production of stoneware bangles flourished in the Indus Valley throughout the civilization's Mature Period (2600-1900 BCE).[14][15]

Another early example of stoneware has been found in China, naturally as an extension of higher temperatures achieved from early development of reduction firing.[16] 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.[17][18]

Other notable historical examples include:

See also

Notes and references

Notes
    References
    1. Standard Terminology of Ceramic Whiteware and Related Products: ASTM Standard C242.
    2. Clay vitrifying temperatures
    3. 1 2 Arthur Dodd & David Murfin. Dictionary of Ceramics; 3rd edition. The Institute of Minerals, 1994.
    4. Encyclopedia Britannica Jasperware is unglazed stoneware
    5. Cuff, Yvonne Hutchinson. Ceramic Technology for Potters and Sculptors. London: A.&C. Black, 1994, p. 64.
    6. Cripss, J.C.; Reeves, G.M.; and Sims, I. Clay Materials Used in Construction. London: The Geological Society, 2006, p. 408.
    7. Rhodes, Daniel and Hopper, Robin. Clay and Glazes for the Potter. Iola, Wisc.: Krause Publications, 2000, p. 109.
    8. Paul Rado An Introduction to the Technology of Pottery; 2nd ed. Oxford: Published on behalf of the Institute of Ceramics by Pergamon, 1988 ISBN 0-08-034932-3
    9. W. Ryan & C. Radford. Whitewares: production, testing and quality control. Oxford: Published on behalf of the Institute of Ceramics by Pergamon, 1987 ISBN 0-08-034927-7
    10. F. Singer & S. S. Singer. Industrial Ceramics. London: Chapman & Hall, 1963
    11. 1 2 3 Dictionary Of Ceramics. Arthur Dodd & David Murfin. 3rd edition. The Institute Of Minerals. 1994.
    12. Arthur Dodd & David Murfin. Dictionary of Ceramics; 3rd edition. The Institute Of Minerals, 1994.
    13. Mark Kenoyer, Jonathan (1998). Ancient Cities of the Indus Valley Civilization. Oxford University Press. p. 260.
    14. Satyawadi, Sudha (July 1, 1994). Proto-Historic Pottery of Indus Valley Civilization; Study of Painted Motif. D.K. Printworld. p. 324. ISBN 978-8124600306.
    15. Blackman et all (1992). The Production and Distribution of Stoneware Bangles at Mohenjo-daro and Harappa as Monitored by Chemical Characterization Studies. Madison, WI, USA: Prehistory Press. pp. 37–44.
    16. Sato, Masahiko. Chinese Ceramics: A Short History (1st edition). John Weatherhill, Inc. (1981), p.15.
    17. Li, He. Chinese Ceramics: A New Comprehensive Survey. Rizzoli International Publications, Inc. New York, New York (1996), p. 39.
    18. Rhodes, Daniel. Stoneware and Porcelain: The Art of High-Fired Pottery. Chilton Co., Philadelphia, Pennsylvania (1959), pp. 7 - 8.
    19. The Discovery Of European Porcelain By Bottger - A Systematic Creative Development. W. Schule, W. Goder. Keram. Z. 34, (10), 598, 1982
    20. 300th Anniversary. Johann Friedrich Bottger - The Inventor Of European Porcelain. Interceram 31, (1), 15, 1982
    21. Invention Of European Porcelain. M. Mields. Sprechsaal 115, (1), 64, 1982
    22. "WedgwoodŽ Official UK Site: Wedgwood China, Fine China Tableware and Gifting". Wedgwood.com. Retrieved 2012-04-26.
    23. "Cane Ware". Wedgwoodsocalif.org. 2012-01-23. Retrieved 2012-04-26.
    24. Salt glazed stoneware. E.A.Barber. Hodder & Stoughton, 1907
    25. "Wedgwood Official UK Site: Wedgwood". Wedgwood.com. Retrieved 2012-04-26.
    26. Wedgwood and his imitators. N.H.Moore. Frederick A. Stokes Company, 1909.

    External links

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