Earthenware

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Painted, incised and glazed earthenware. Dated 10th century, Iran. New York Metropolitan Museum of Art

Earthenware is the general term for pottery that is not porcelain or some other specific types such as fritware or stoneware. It is, or can be, fired at relatively low temperatures and vitrification does not take place, leaving the body (if not glazed) slightly porous.[1] Until porcelain became very widely used in the modern period, the great majority of pottery from the earliest times onwards was of types classed as earthenware. Pit fired earthenware dates back to as early as 29,000–25,000 BCE.[2][3] Porcelain only began to be manufactured outside East Asia in the 18th-century, and then as an expensive luxury. Unlike porcelain, earthenware is not translucent, and it is normally relatively thick and very heavy. It is far easier to make than porcelain, as a wide range of clays can be used, and it is much more tolerant of low and variable firing temperatures. Most modern craft and amateur pottery is earthenware.

After firing the body is porous and opaque, and depending on the raw materials used will be colored from white to buff to red. Earthenware articles may sometimes be as thin as bone china and other porcelains, though they are not translucent and are more easily chipped. Earthenware is also less strong, less tough and more porous than stoneware, but is less expensive and easier to work. Due to its higher porosity, it must usually be glazed in order to be watertight. Any body (i.e. the mixed raw materials) that is suitable for porcelain or stoneware will produce earthenware if fired at a lower temperature.[4]

Types of earthenware[edit]

Chinese earthenware tomb sculpture[5] The Walters Art Museum.

There are several types of earthenware, including

Firing[edit]

Two panels of earthenware tiles painted with polychrome glazes over a white glaze. (19th)

Modern studio earthenware is commonly biscuit (or "bisque")[6][7] fired to temperatures between 1000 and 1150 °C (1800 and 2100 °F), and glost-fired[8] (or "glaze-fired")[9][10] from 950 to 1,050 °C (1,740 to 1,920 °F). However, the reverse — low bisque and high gloss firing — can sometimes be found: this can be popular with some studio potters where bisque temperatures may be 900 to 1,050 °C (1,650 to 1,920 °F) with gloss temperatures around 1,040 to 1,150 °C (1,900 to 2,100 °F). The exact temperature will be influenced by the raw materials used and the desired characteristics of the finished ware. Higher firing temperatures are likely to cause earthenware to bloat. For red earthenware, firing temperatures in the bisque kiln can dramatically effect the color of the clay body. Firing at lower temperatures (cone 4 or 5) will cause the bright red color; the hotter it is fired, the darker and less stable it becomes. When fired at a very hot temperature, the clay body becomes extremely weak in the kiln and warps and sags dramatically along with turning a dark black.

Notes[edit]

  1. ^ "Earthenware" Britannica online
  2. ^ "Modern Ceramic Engineering: Properties, Processing And Use In Design." D.W. Richerson. CRC Press. 2006.
  3. ^ "On the Origins of Pottery." P.M.Rice. Journal of Archaeological Method and Theory. Vol 6, No.1. 1999.
  4. ^ Petersons, 123-124
  5. ^ "Women on Horseback". The Walters Art Museum. 
  6. ^ Rich, Jack C. (1988). The Materials and Methods of Sculpture. Courier Dover Publications. p. 49. ISBN 9780486257426. 
  7. ^ "Ceramic Arts Daily – Ten Basics of Firing Electric Kilns". ceramicartsdaily.org. 2012. Retrieved 16 April 2012. 
  8. ^ Norton, F.H. (1960). Ceramics an Illustrated Primer. Hanover House. pp. 74–79. 
  9. ^ Billington, Dora. (1962). The Technique of Pottery. B.T.Batsford LTD. p. 161. 
  10. ^ Frank and Janet Hamer, The Potter's Dictionary of Materials and Techniques

References[edit]

  • Rado, P. An Introduction to the Technology Of Pottery. 2nd edition. Pergamon Press, 1988.
  • Ryan W. and Radford, C. Whitewares: Production, Testing And Quality Control. Pergamon Press, 1987.
  • Hamer, Frank and Janet. The Potter's Dictionary of Materials and Techniques. A & C Black Publishers Limited, London, England, Third Edition, 1991. ISBN 0-8122-3112-0.
  • "Petersons": Peterson, Susan, Peterson, Jan, The Craft and Art of Clay: A Complete Potter's Handbook, 2003, Laurence King Publishing, ISBN 1856693546, 9781856693547, google books

External links[edit]