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Porcelain () is a
ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...
material made by heating substances, generally including materials such as kaolinite, in a
kiln A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
to temperatures between . The strength and translucence of porcelain, relative to other types of
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 ...
, arises mainly from
vitrification Vitrification (from Latin ''vitreum'', "glass" via French ''vitrifier'') is the full or partial transformation of a substance into a glass, that is to say, a non- crystalline amorphous solid. Glasses differ from liquids structurally and glasses po ...
and formation of the mineral
mullite Mullite or porcelainite is a rare silicate mineral formed during contact metamorphism of clay minerals. It can form two stoichiometric forms: 3 Al2 O32 SiO2 or 2Al2O3 SiO2. Unusually, mullite has no charge-balancing cations present. As a result, th ...
within the body at these high temperatures. Though definitions vary, porcelain can be divided into three main categories: hard-paste, soft-paste, and
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 phospha ...
. The category that an object belongs to depends on the composition of the paste used to make the body of the porcelain object and the firing conditions. Porcelain slowly evolved in China and was finally achieved (depending on the definition used) at some point about 2,000 to 1,200 years ago; it slowly spread to other East Asian countries, then to Europe, and eventually to the rest of the world. Its manufacturing process is more demanding than that for 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 vi ...
, the two other main types of pottery, and it has usually been regarded as the most prestigious type of pottery for its delicacy, strength, and its white colour. It combines well with both glazes and paint, and can be modelled very well, allowing a huge range of decorative treatments in
tableware Tableware is any dish or dishware used for setting a table, serving food, and dining. It includes cutlery, glassware, serving dishes, and other items for practical as well as decorative purposes. The quality, nature, variety and number of o ...
, vessels, and
figurine A figurine (a diminutive form of the word ''figure'') or statuette is a small, three-dimensional sculpture that represents a human, deity or animal, or, in practice, a pair or small group of them. Figurines have been made in many media, with clay ...
s. It also has many uses in technology and industry. The European name, porcelain in English, comes from the old Italian ''porcellana'' ( cowrie shell) because of its resemblance to the surface of the shell. Porcelain is also referred to as china or fine china in some English-speaking countries, as it was first seen in imports from China during the 17th century.
Properties Property is the ownership of land, resources, improvements or other tangible objects, or intellectual property. Property may also refer to: Mathematics * Property (mathematics) Philosophy and science * Property (philosophy), in philosophy an ...
associated with porcelain include low permeability and elasticity; considerable
strength Strength may refer to: Physical strength *Physical strength, as in people or animals * Hysterical strength, extreme strength occurring when people are in life-and-death situations *Superhuman strength, great physical strength far above human c ...
,
hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
, whiteness,
translucency In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions ...
, and
resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied Periodic function, periodic force (or a Fourier analysis, Fourier component of it) is equal or close to a natural frequency of the system ...
; and a high resistance to corrosive chemicals and
thermal shock Thermal shock is a type of rapidly transient mechanical load. By definition, it is a mechanical load caused by a rapid change of temperature of a certain point. It can be also extended to the case of a thermal gradient, which makes different pa ...
. Porcelain has been described as being "completely vitrified, hard, impermeable (even before glazing), white or artificially coloured, translucent (except when of considerable thickness), and resonant". However, the term "porcelain" lacks a universal definition and has "been applied in an unsystematic fashion to substances of diverse kinds which have only certain surface-qualities in common". Traditionally, East Asia only classifies pottery into low-fired wares (earthenware) and high-fired wares (often translated as porcelain), the latter also including what Europeans call "stoneware", which is high-fired but not generally white or translucent. Terms such as "proto-porcelain", "porcellaneous" or "near-porcelain" may be used in cases where the ceramic body approaches whiteness and translucency.


Types


Hard paste

Hard-paste porcelain was invented in China, and it was also used in
Japanese porcelain , is one of the oldest Japanese crafts and art forms, dating back to the Neolithic period. Kilns have produced earthenware, pottery, stoneware, glazed pottery, glazed stoneware, porcelain, and blue-and-white ware. Japan has an exceptional ...
, and most of the finest quality porcelain wares are in this material. The earliest European porcelains were produced at the Meissen factory in the early 18th century; they were formed from a paste composed of
kaolin Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...
and
alabaster Alabaster is a mineral or rock that is soft, often used for carving, and is processed for plaster powder. Archaeologists and the stone processing industry use the word differently from geologists. The former use it in a wider sense that include ...
and fired at temperatures up to in a wood-fired kiln, producing a porcelain of great hardness, translucency, and strength. Later, the composition of the Meissen hard paste was changed and the alabaster was replaced by
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) felds ...
and
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 ...
, allowing the pieces to be fired at lower temperatures. Kaolinite, feldspar and quartz (or other forms of
silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
) continue to constitute the basic ingredients for most continental European hard-paste porcelains.


Soft paste

Soft-paste porcelains date back from early attempts by European potters to replicate Chinese porcelain by using mixtures of clay and
frit A frit is a ceramic composition that has been fused, quenched, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes; the purpose of this pre-fusion is to render any soluble and/or toxic compo ...
. Soapstone and lime are known to have been included in these compositions. These wares were not yet actual porcelain wares as they were neither hard nor vitrified by firing
kaolin Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...
clay at high temperatures. As these early formulations suffered from high pyroplastic deformation, or slumping in the kiln at high temperatures, they were uneconomic to produce and of low quality. Formulations were later developed based on kaolin with quartz, feldspars,
nepheline syenite Nepheline syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are al ...
or other feldspathic rocks. These are technically superior, and continue to be produced. Soft-paste porcelains are fired at lower temperatures than hard-paste porcelain, therefore these wares are generally less hard than hard-paste porcelains.


Bone china

Although originally developed in England in 1748 to compete with imported porcelain,
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 phospha ...
is now made worldwide, including China. The English had read the letters of Jesuit missionary
François Xavier d'Entrecolles François Xavier d'Entrecolles (1664 in Lyon – 1741 in Beijing; Chinese name: 殷弘绪, Yin Hongxu) was a French Jesuit priest, who learned the Chinese technique of manufacturing porcelain through his investigations in China at Jingdezhen with ...
, which described Chinese porcelain manufacturing secrets in detail. One writer has speculated that a misunderstanding of the text could possibly have been responsible for the first attempts to use bone-ash as an ingredient of English porcelain, although this is not supported by modern researchers and historians. Traditionally, English bone china was made from two parts of
bone ash Bone ash is a white material produced by the calcination of bones. Typical bone ash consists of about 55.82% calcium oxide, 42.39% phosphorus pentoxide, and 1.79% water. The exact composition of these compounds varies depending upon the type of bo ...
, one part of
kaolin Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...
and one part
china stone China stone is a medium grained, feldspar-rich partially kaolinised granite characterized by the absence of iron-bearing minerals.