HOME

TheInfoList



OR:

Earthenware is glazed or unglazed nonvitreous
pottery Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and po ...
that has normally been fired below . Basic earthenware, often called
terracotta Terracotta, terra cotta, or terra-cotta (; ; ), in its material sense as an earthenware substrate, is a clay-based unglazed or glazed ceramic where the fired body is porous. In applied art, craft, construction, and architecture, terracotta i ...
, 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 holdi ...
, which the great majority of modern domestic earthenware has. The main other important types of pottery are
porcelain Porcelain () is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pottery, arises main ...
,
bone china Bone china is a type of ceramic that is composed of bone ash, feldspathic material, and kaolin. It has been defined as "ware with a translucent body" containing a minimum of 30% of phosphate derived from animal bone and calculated calcium phos ...
, and
stoneware Stoneware is a rather broad term for pottery or other ceramics fired at a relatively high temperature. A modern technical definition is a vitreous or semi-vitreous ceramic made primarily from stoneware clay or non- refractory fire clay. Whether ...
, 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 East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea ...
, 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 The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been ...
describes it as being made of selected
clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay part ...
s sometimes mixed with
feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feld ...
s 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 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 ...
, roller-head or
potter's wheel In pottery, a potter's wheel is a machine used in the shaping (known as throwing) of clay into round ceramic ware. The wheel may also be used during the process of trimming excess clay from leather-hard dried ware that is stiff but malleable, ...
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 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 Terracotta, terra cotta, or terra-cotta (; ; ), in its material sense as an earthenware substrate, is a clay-based unglazed or glazed ceramic where the fired body is porous. In applied art, craft, construction, and architecture, terracotta i ...
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.


Production

A general body formulation for contemporary earthenware is 25% kaolin, 25% ball clay, 35%
quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...
and 15%
feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feld ...
. Modern earthenware may be biscuit (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 Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...
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 ...
of the late Middle Ages, which developed into
tin-glazed pottery Tin-glazed pottery is earthenware covered in lead glaze with added tin oxide which is white, shiny and opaque (see tin-glazing for the chemistry); usually this provides a background for brightly painted decoration. It has been important in ...
or
faience Faience or faïence (; ) is the general English language term for fine tin-glazed pottery. The invention of a white pottery glaze suitable for painted decoration, by the addition of an oxide of tin to the slip of a lead glaze, was a major ad ...
traditions in several parts of Europe, mostly notably the painted
maiolica Maiolica is tin-glazed pottery decorated in colours on a white background. Italian maiolica dating from the Renaissance period is the most renowned. When depicting historical and mythical scenes, these works were known as ''istoriato'' wares ...
of the Italian Renaissance, and Dutch Delftware. With a white glaze, these were able to imitate porcelains both from
East Asia East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea ...
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 Wedgwood is an English fine china, porcelain and luxury accessories manufacturer that was founded on 1 May 1759 by the potter and entrepreneur Josiah Wedgwood and was first incorporated in 1895 as Josiah Wedgwood and Sons Ltd. It was rap ...
's creamware, that competed with porcelain with considerable success, as his huge creamware Frog Service for Catherine the Great 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 ''Sancai'' ()Vainker, 75 is a versatile type of decoration on Chinese pottery using glazes or slip, predominantly in the three colours of brown (or amber), green, and a creamy off-white. It is particularly associated with the Tang Dynasty (61 ...
glazed wares were lead-glazed earthenware, and as elsewhere, terracotta remained important for sculpture. The
Etruscans The Etruscan civilization () was developed by a people of Etruria in ancient Italy with a common language and culture who formed a federation of city-states. After conquering adjacent lands, its territory covered, at its greatest extent, roug ...
had made large sculptures such as statues in it, where the Romans used it mainly for figurines and Campana reliefs. 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 Terracotta, terra cotta, or terra-cotta (; ; ), in its material sense as an earthenware substrate, is a clay-based unglazed or glazed ceramic where the fired body is porous. In applied art, craft, construction, and architecture, terracotta i ...
: a term used for a rather random group of types of objects, rather than being defined by technique * Redware (America) *
Victorian majolica Victorian majolica properly refers to two types of majolica made in the second half of the 19th century in Europe and America. Firstly, and best known, there is the mass-produced majolica decorated with coloured lead glazes, made in Britain, Eur ...
* Lusterware with special iridescent glazes * Raku * Ironstone china, on the border of earthenware and
stoneware Stoneware is a rather broad term for pottery or other ceramics fired at a relatively high temperature. A modern technical definition is a vitreous or semi-vitreous ceramic made primarily from stoneware clay or non- refractory fire clay. Whether ...
* Yellowware


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