Earthenware architecture models, Eastern Han Dynasty, 7.JPG
   HOME

TheInfoList



OR:

Earthenware is glazed or unglazed nonvitreous pottery that has normally been fired below . Basic earthenware, often called terracotta, absorbs liquids such as water. However, earthenware can be made impervious to liquids by coating it with a
ceramic glaze Ceramic glaze is an impervious layer or coating of a vitreous substance which has been fused to a pottery body through firing. Glaze can serve to color, decorate or waterproof an item. Glazing renders earthenware vessels suitable for holding ...
, which the great majority of modern domestic earthenware has. The main other important types of pottery are porcelain, bone china, and stoneware, all fired at high enough temperatures to vitrify. 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" ("today" being 1962).Dora Billington, ''The Technique of Pottery'', London: B.T.Batsford, 1962 Pit fired earthenware dates back to as early as 29,000–25,000 BC, 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,Combined Nomenclature of the European Union published by the EC Commission in Luxembourg, 1987 soft and capable of being scratched with a knife. The Combined Nomenclature of the European Union 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).


Characteristics

Generally, earthenware bodies exhibit higher
plasticity Plasticity may refer to: Science * Plasticity (physics), in engineering and physics, the propensity of a solid material to undergo permanent deformation under load * Neuroplasticity, in neuroscience, how entire brain structures, and the brain it ...
than most whiteware bodies and hence are easier to shape by
RAM press A RAM press (or ram press) is a machine, invented in the USA in the mid-1940s, that is used to press clay into moulded shapes, such as plates and bowls. In operation a slice of de-aired clay body is placed in between two shaped porous moulds, a ...
, roller-head or potter's wheel than bone china or porcelain.Whitewares: Testing and Quality Control. W.Ryan and C.Radford. Institute of Ceramics & Pergamon. 1987. Due to its porosity, earthenware, with a water absorption of 5-8%, must be glazed to be watertight. Earthenware has lower
mechanical strength The field of strength of materials, also called mechanics of materials, typically refers to various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the re ...
than bone china, porcelain or stoneware, and consequently articles are commonly made in thicker cross-section, although they are still more easily chipped. Darker-colored terracotta earthenware, typically orange or red due to a comparatively high content of
iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of whic ...
, are widely used for flower pots, tiles and some decorative and oven ware.


Production

A general body formulation for contemporary earthenware is 25% kaolin, 25% ball clay, 35% quartz and 15% feldspar. Modern earthenware may be
biscuit A biscuit is a flour-based baked and shaped food product. In most countries biscuits are typically hard, flat, and unleavened. They are usually sweet and may be made with sugar, chocolate, icing, jam, ginger, or cinnamon. They can also be ...
(or "bisque") fired to temperatures between and glost-fired (or "glaze-fired")Frank and Janet Hamer, ''The Potter's Dictionary of Materials and Techniques'' to between , 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 and many clays will not fire successfully above about . Much historical pottery was fired somewhere around , 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

Despite the most highly valued types of pottery often switching to stoneware and porcelain as these were developed by a particular culture, there are many artistically important types of earthenware. All Ancient Greek and Ancient Roman pottery is earthenware, as is the
Hispano-Moresque ware Hispano-Moresque ware is a style of initially Islamic pottery created in Al-Andalus, which continued to be produced under Christian rule in styles blending Islamic and European elements. It was the most elaborate and luxurious pottery being pr ...
of the late Middle Ages, which developed into tin-glazed pottery or faience traditions in several parts of Europe, mostly notably the painted maiolica of the Italian Renaissance, and Dutch Delftware. With a white glaze, these were able to imitate porcelains both from East Asia and Europe. Possibly the most complicated earthenware ever made was the extremely rare
Saint-Porchaire ware Saint-Porchaire ware is the earliest very high quality French pottery. It is white lead-glazed earthenware often conflated with true faience, that was made for a restricted French clientele from perhaps the 1520s to the 1550s. Only about seventy p ...
of the mid-16th century, apparently made for the French court. In the 18th century, especially in English Staffordshire pottery, technical improvements enabled very fine wares such as Wedgwood's creamware, that competed with porcelain with considerable success, as his huge creamware Frog Service for
Catherine the Great , en, Catherine Alexeievna Romanova, link=yes , house = , father = Christian August, Prince of Anhalt-Zerbst , mother = Joanna Elisabeth of Holstein-Gottorp , birth_date = , birth_name = Princess Sophie of Anhal ...
showed. The invention of transfer printing processes made highly decorated wares cheap enough for far wider sections of the population in Europe. In China, sancai glazed wares were lead-glazed earthenware, and as elsewhere, terracotta remained important for sculpture. The Etruscans had made large sculptures such as statues in it, where the Romans used it mainly for figurines and
Campana relief Campana reliefs (also Campana tiles) are Ancient Roman terracotta reliefs made from the middle of the first century BC until the first half of the second century AD. They are named after the Italian collector Giampietro Campana, who first published ...
s. Chinese painted or Tang dynasty tomb figures were earthenware, as were later sculptures such as the near life-size
Yixian glazed pottery luohans A set of life-size glazed pottery sculptures of luohans usually assigned to the period of the Liao dynasty (907–1125) was discovered in caves at I Chou (I-chou, Yizhou) in Yi xian or Yi County, Hebei (), south of Beijing, before World War I. ...
. After the ceramic figurine was revived in European porcelain, earthenware figures followed, such as the popular English
Staffordshire figures Staffordshire figures are a type of popular pottery figurine made in England from the 18th century onward. Most Staffordshire figures made from 1740 to 1900 were produced by small potteries and makers' marks are generally absent. Most Victorian f ...
. There are other several types of earthenware, including: * Terracotta: a term used for a rather random group of types of objects, rather than being defined by technique *
Redware Redware as a single word is a term for at least two types of pottery of the last few centuries, in Europe and North America. Red ware as two words is a term used for pottery, mostly by archaeologists, found in a very wide range of places. Howeve ...
(America) * Victorian majolica * Lusterware with special iridescent glazes * Raku * Ironstone china, on the border of earthenware and stoneware *
Yellowware Yellowware, or yellow ware, is a type of earthenware named after its yellow appearance given to it by the clay used for its production. Originating in the United Kingdom in the late 18th century, it was also produced in the eastern United State ...


References


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. . * "Petersons": Peterson, Susan, Peterson, Jan, ''The Craft and Art of Clay: A Complete Potter's Handbook'', 2003, Laurence King Publishing, , 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 {{Authority control Clay Ceramic materials Crockery Pottery Serving vessels Cooking vessels Food storage containers