Earthenware
Earthenware is glazed or unglazed nonvitreous pottery[2] that has normally been fired below 1200°C.[3]Porcelain, bone china and stoneware, all fired at high enough temperatures to vitrify, are the main other important types of pottery.
Earthenware comprises
most building bricks, nearly all European pottery up to the seventeenth century, most of the wares of Egypt, Persia and the near East; Greek, Roman and Mediterranean, and some of the Chinese; and the fine earthenware which forms the greater part of our tableware today.[4]
Pit fired earthenware dates back to as early as 29,000–25,000 BC,[5][6] and for millennia, only earthenware pottery was made, with stoneware gradually developing some 5,000 years ago, but then apparently disappearing for a few thousand years. Outside East Asia, porcelain was manufactured only from the 18th century AD, and then initially as an expensive luxury.
After it is fired, earthenware is opaque and non-vitreous,[7] soft and capable of being scratched with a knife.[4] The Combined Nomenclature of the European Communities describes it as being made of selected clays sometimes mixed with feldspars and varying amounts of other minerals, and white or light-colored (i.e., slightly greyish, cream, or ivory).[7]
Contents
1 Characteristics
2 Production
3 Types of earthenware
4 References
5 Further reading
6 External links
Characteristics
Generally, earthenware bodies exhibit higher plasticity than most whiteware[8] bodies and hence are easier to shape by RAM press, roller-head or potter's wheel than bone china or porcelain.[9][10]
Due to its porosity, earthenware, with a water absorption of 5-8%, must be glazed to be watertight.[11] Earthenware has lower mechanical strength than bone china, porcelain or stoneware, and consequently articles are commonly made in thicker cross-section, although they are still more easily chipped.[9]
Darker-colored terracotta earthenware, typically orange or red due to a comparatively high content of iron oxide, are widely used for flower pots, tiles and some decorative and oven ware.[4]
Production
A general body formulation for contemporary earthenware is 25% kaolin, 25% ball clay, 35% quartz and 15% feldspar.[9][12]
Modern earthenware may be biscuit (or "bisque")[13][14] fired to temperatures between 1,000 to 1,150 °C (1,830 to 2,100 °F) and glost-fired[15] (or "glaze-fired")[4][16] to between 950 to 1,050 °C (1,740 to 1,920 °F), the usual practice in factories and some studio potteries. Some studio potters follow the reverse practice, with a low-temperature biscuit firing and a high-temperature glost firing. The firing schedule will be determined by the raw materials used and the desired characteristics of the finished ware.
Historically, such high temperatures were unattainable in most cultures and periods until modern times, though Chinese ceramics were far ahead of other cultures in this respect. Earthenware can be produced at firing temperatures as low as 600 °C (1,112 °F) and many clays will not fire successfully above about 1,000 °C (1,830 °F). Much historical pottery was fired somewhere around 800 °C (1,470 °F), giving a wide margin of error where there was no precise way of measuring temperature, and very variable conditions within the kiln.
After firing, most earthenware bodies will be colored white, buff or red. For red earthenware, the firing temperature affects the color of the clay body. Lower temperatures produce a typical red terracotta color; higher temperatures will make the clay brown or even black. Higher firing temperatures may cause earthenware to bloat.
Types of earthenware
There are several types of earthenware, including:
Terracotta: a term used for a rather random group of types of objects, rather than being defined by technique
Tin-glazed pottery, or Faience- Maiolica
- Delftware
- Lead-glazed earthenware
Redware (America)- Victorian majolica
- Creamware
Lusterware with special iridescent glazes- Raku
Ironstone china, on the border of earthenware and stoneware- Yellowware
References
^ "Brooklyn Museum". www.brooklynmuseum.org. Archived from the original on 30 April 2018. Retrieved 30 April 2018..mw-parser-output cite.citationfont-style:inherit.mw-parser-output qquotes:"""""""'""'".mw-parser-output code.cs1-codecolor:inherit;background:inherit;border:inherit;padding:inherit.mw-parser-output .cs1-lock-free abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-lock-subscription abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registrationcolor:#555.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration spanborder-bottom:1px dotted;cursor:help.mw-parser-output .cs1-hidden-errordisplay:none;font-size:100%.mw-parser-output .cs1-visible-errorfont-size:100%.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-formatfont-size:95%.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-leftpadding-left:0.2em.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-rightpadding-right:0.2em
^ ASTM C242 – 15. Standard Terminology Of Ceramic Whitewares And Related Products
^ "Art & Architecture Thesaurus Full Record Display (Getty Research)". www.getty.edu. Archived from the original on 22 December 2017. Retrieved 30 April 2018.
^ abcd Dora Billington, The Technique of Pottery, London: B.T.Batsford, 1962
^ David W. Richerson; William Edward Lee (31 January 1992). Modern Ceramic Engineering: Properties, Processing, and Use in Design, Third Edition. CRC Press. ISBN 978-0-8247-8634-2.
^ Rice, Prudence M. (March 1999). "On the Origins of Pottery". Journal of Archaeological Method and Theory. 6 (1): 1–54. doi:10.1023/A:1022924709609.
^ ab Combined Nomenclature of the European Union Published by the EC Commission in Luxembourg, 1987
^ An industry term for ceramics including tableware and sanitary ware
^ abc Whitewares: Testing and Quality Control. W.Ryan and C.Radford. Institute of Ceramics & Pergamon. 1987.
^ Pottery Science: Materials, Process And Products. Allen Dinsdale. Ellis Horwood. 1986.
^ Ceramics Glaze Technology. J. R. Taylor & A. C. Bull. Institute of Ceramics & Pergamon Press. 1986
^ Dictionary of Ceramics, 3rd edition. A. E. Dodd & D. Murfin. Maney Publishing. 1994.
^ Rich, Jack C. (1988). The Materials and Methods of Sculpture. Courier Dover Publications. p. 49. ISBN 9780486257426.
^ "Ceramic Arts Daily – Ten Basics of Firing Electric Kilns". ceramicartsdaily.org. 2012. Archived from the original on 8 May 2012. Retrieved 16 April 2012.
^ Norton, F.H. (1960). Ceramics an Illustrated Primer. Hanover House. pp. 74–79.
^ Frank and Janet Hamer, The Potter's Dictionary of Materials and Techniques
^ "Women on Horseback". The Walters Art Museum. Archived from the original on 2016-03-04.
Further reading
- 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
Digital Version of "A Representation of the manufacturing of earthenware" — 1827 text on the manufacture of earthenware- Short film on pottery making around the world
Tin-glazed earthenware livery-button, ca 1651, Victoria & Albert museum jewellery collection