Porcelain is a ceramic A ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous . Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the non- material made by heating raw materials, generally including clay Clay is a naturally occurring material composed primarily of fine-grained minerals. Clay deposits are mostly composed of clay minerals, a subtype of phyllosilicate minerals, which impart plasticity and harden when fired or dried; they also may contain variable amounts of water trapped in the mineral structure by polar attraction. Organic materials in the form of kaolin Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O54. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra. Rocks that are rich in kaolinite are known as china clay, white clay, or kaolin, in a kiln Kilns are an essential part of the manufacture of all ceramics, which, by definition, require heat treatment, often at high temperature. During this process, chemical and physical reactions occur which cause the material to be permanently altered. In the case of pottery, clay materials are shaped, dried and then fired in a kiln. The final to temperatures between 1,200 °C Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale two years before his death. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature interval (a difference between two temperatures (2,192 °F Fahrenheit is the temperature scale proposed in 1724 by, and named after, the physicist Daniel Gabriel Fahrenheit . Today, the temperature scale has been replaced by the Celsius scale in most countries. It is still in use in few nations, such as United States and Belize) and 1,400 °C (2,552 °F). The toughness, strength, and translucence In the field of optics, transparency is the physical property of allowing light to pass through a material; translucency (also called translucence or translucidity) only allows light to pass through diffusely. The opposite property is opacity. Transparent materials are clear, while translucent ones cannot be seen through clearly of porcelain arise mainly from the formation of glass Glass is an amorphous solid material. Glasses are typically brittle, and often optically transparent. Glass is commonly used for windows, bottles, and eyewear; examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovy-glass, and aluminium oxynitride. The term glass developed in the late Roman and the mineral mullite Mullite or porcelainite is a rare silicate mineral of post-clay genesis. It can form two stoichiometric forms 3Al2O32SiO2 or 2Al2O3 SiO2. Unusually, mullite has no charge balancing cations present therefore there are three different Al sites: two distorted tetrahedral Al sites and one Al other site which adopts a higher co-ordinate octahedral within the fired body at these high temperatures.

Porcelain derives its present name from old Italian Italian ( italiano , or lingua italiana) is a Romance language spoken as a native language by about 70 million people in Italy, San Marino and parts of Switzerland, Croatia, Slovenia and France. In addition, it is spoken by an additional 120 to 150 million people as a non-native language. Most native speakers are native bilinguals of both porcellana (cowrie shell Cowry, also sometimes spelled cowrie, plural cowries, is the common name for a group of small to large marine gastropods in the family Cypraeidae. The word cowry is also often used to refer to the shells of these snails) because of its resemblance to the translucent surface of the shell.^[1] Porcelain can informally be referred to as "china" in some English-speaking countries, as China China is seen variously as an ancient civilization extending over a large area in East Asia, a nation and/or a multinational entity was the birth place of porcelain making.^[2] Properties Property is any physical or intangible entity that is owned by a person or jointly by a group of persons. Depending on the nature of the property, an owner of property has the right to consume, sell, rent, mortgage, transfer, exchange or destroy their property, and/or to exclude others from doing these things. Important widely recognized types of associated with porcelain include low permeability and elasticity In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform is removed. The relative amount of deformation is called the strain; considerable strength In materials science, the strength of a material is its ability to withstand an applied stress without failure. Yield strength refers to the point on the engineering stress-strain curve beyond which the material begins deformation that cannot be reversed upon removal of the loading. Ultimate strength refers to the point on the engineering stress-, hardness Hardness is the measure of how resistant solid matter is to various kinds of permanent shape change when a force is applied. Macroscopic hardness is generally characterized by strong intermolecular bonds, however the behavior of solid materials under force is complex, therefore there are different measurements of hardness: scratch hardness,, glassiness, brittleness A material is brittle if it is liable to fracture when subjected to stress. That is, it has little tendency to deform before fracture. This fracture absorbs relatively little energy, even in materials of high strength, and usually makes a snapping sound, whiteness White is a color, the perception which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness, translucence In the field of optics, transparency is the physical property of allowing light to pass through a material; translucency (also called translucence or translucidity) only allows light to pass through diffusely. The opposite property is opacity. Transparent materials are clear, while translucent ones cannot be seen through clearly, and resonance In physics, resonance is the tendency of a system to oscillate with larger amplitude at some frequencies than at others. These are known as the system's resonant frequencies (or resonance frequencies). At these frequencies, even small periodic driving forces can produce large amplitude oscillations; and a high resistance to chemical attack and thermal shock Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high thermal expansion coefficients. However, they are used in many high temperature applications due to their high melting.

For the purposes of trade, the Combined Nomenclature of the European Communities defines porcelain 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 a very unsystematic fashion to substances of diverse kinds which have only certain surface-qualities in common" (Burton 1906).

Porcelain is used to make table, kitchen, sanitary, and decorative wares; objects of fine art; and tiles A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass. Tiles are generally used for covering roofs, floors, walls, showers, or other objects such as tabletops. Alternatively, tile can sometimes refer to similar units made from lightweight materials such as perlite, wood, and mineral wool, typically. Its high resistance to the passage of electricity makes porcelain an excellent insulator An insulator, also called a dielectric, is a material that resists the flow of electric current. An insulating material has atoms with tightly bonded valence electrons. These materials are used in parts of electrical equipment, also called insulators or insulation, intended to support or separate electrical conductors without passing current. Dental porcelain Dental porcelain is a porcelain used by a dental technician to create biocompatible lifelike crowns, bridges, and veneers for the patient. Evidence suggests they are effective, although for three-unit molars porcelain fused to metal or in complete porcelain group only zirconia-based restorations are recommended is used to make false teeth, caps, crowns and veneers In dentistry, a veneer is a thin layer of restorative material placed over a tooth surface, either to improve the aesthetics of a tooth, or to protect a damaged tooth surface. There are two main types of material used to fabricate a veneer, composite and dental porcelain. A composite veneer may be directly placed , or indirectly fabricated by a.

Scope, materials and methods

Scope

The most common uses of porcelain are the creation of artistic objects and the production of more utilitarian wares. It is difficult to distinguish between stoneware "Stoneware, which, though dense, impermeable and hard enough to resist scratching by a steel point, differs from porcelain because it is more opaque, and normally only partially vitrified. It may be vitreous or semi-vitreous. It is usually coloured grey or brownish because of impurities in the clay used for its manufacture, and is normally and porcelain because this depends upon how the terms are defined. A useful working definition of porcelain might include a broad range of ceramic wares, including some that could be classified as a stoneware.

Materials

Clay is generally thought to be the primary material from which porcelain is made, even though clay minerals might account for only a small proportion of the whole. The word "paste" is an old term for both the unfired and fired material. A more common terminology these days for the unfired material is "body", for example, when buying materials a potter might order an amount of porcelain body from a vendor.

The composition of porcelain is highly variable, but the clay mineral kaolinite Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O54. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra. Rocks that are rich in kaolinite are known as china clay, white clay, or kaolin is often a significant component. Other materials can include feldspar Feldspars crystallize from magma in both intrusive and extrusive igneous rocks, as veins, and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of sedimentary rock, ball clay Ball clays are kaolinitic sedimentary clays, that commonly consist of 20-80% kaolinite, 10-25% mica, 6-65% quartz. Localized seams in the same deposit have variations in composition, including the quantity of the major minerals, accessory minerals and carbonaceous materials such as lignite. They are fine-grained and plastic in nature, glass Glass is an amorphous solid material. Glasses are typically brittle, and often optically transparent. Glass is commonly used for windows, bottles, and eyewear; examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovy-glass, and aluminium oxynitride. The term glass developed in the late Roman, bone ash, steatite Soapstone is a metamorphic rock, a talc-schist. It is largely composed of the mineral talc and is thus rich in magnesium. It is produced by dynamothermal metamorphism and metasomatism, which occurs in the areas where tectonic plates are subducted, changing rocks by heat and pressure, with influx of fluids, but without melting. It has been a medium, quartz Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2, petuntse Petuntse , also spelled petunse, is a historic term for a wide range of micaceous or feldspathic rocks. However, all will have been subject to geological decomposition processes that result in a material which, after processing, is suitable as an ingredient in some ceramic formulations. Petuntse was and continues to be an important ingredient of and alabaster Alabaster is a name applied to varieties of two distinct minerals: gypsum and calcite (a carbonate of calcium). The former is the alabaster of the present day; generally, the latter is the alabaster of the ancients; further information on these formulations is given at "soft-paste porcelain "Soft-paste porcelain" is a type of a ceramic material, but it lacks a more specific, universally agreed definition. Some writers have used the term for body formulations that combine clay and glass frit, mainly in the production of decorative figures and domestic wares in eighteenth century Europe, while others have used the term more".

The clays used are often described as being long or short, depending on their plasticity In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal or plastic being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself. In engineering, the. Long clays are cohesive (sticky) and have high plasticity; short clays are less cohesive and have lower plasticity. In soil mechanics Soil mechanics is a discipline that applies principles of engineering mechanics, e.g. kinematics, dynamics, fluid mechanics, and mechanics of material, to predict the mechanical behavior of soils. Together with rock mechanics, it is the basis for solving many engineering problems in civil engineering , geophysical engineering and engineering, plasticity is determined by measuring the increase in content of water required to change a clay from a solid state bordering on the plastic, to a plastic state bordering on the liquid, though the term is also used less formally to describe the facility with which a clay may be worked. Clays used for porcelain are generally of lower plasticity and are shorter than many other pottery clays. They wet very quickly, meaning that small changes in the content of water can produce large changes in workability. Thus, the range of water content within which these clays can be worked is very narrow and the loss or gain of water during storage and throwing or forming must be carefully controlled to keep the clay from becoming too wet or too dry to manipulate.

Methods

The following section provides background information on the methods used to form, decorate, finish, glaze, and fire ceramic wares.

Forming. is described in the Wikipedia articles Pottery Pottery is the ceramic ware made by potters. The place where such wares are made is also called a pottery . Pottery can also refer to the material of which the potteryware is made. Major types of pottery include earthenware, stoneware and porcelain. Pottery is one of the oldest human technologies and art-forms, and remains a major industry today and Ceramic forming techniques Ceramic forming techniques are ways of forming ceramic shapes. This can be used to make everyday tableware from teapots, to engineering ceramics such as computer parts. Methods for forming ceramic powders into complex shapes are desirable in many areas of technology. For example, such methods are required for producing advanced, high-temperature.

Glazing. Unlike their lower-fired counterparts, porcelain wares do not need glazing to render them impermeable to liquids and for the most part are glazed for decorative purposes and to make them resistant to dirt and staining. Great detail is given in the glaze Glaze is a layer or coating of a vitreous substance which has been fired to fuse to a ceramic object to color, decorate, strengthen or waterproof it article. Many types of glaze, such as the iron-containing glaze used on the celadon wares of Longquan Longquan celadon refers to Chinese celadon produced in Longguan (龍泉) kilns which were largely located in Lishui prefecture in southwestern Zhejiang Province. With those in other prefectures the total of discovered kiln sites is over two hundred, making the Longquan celadon production area one of the largest historical ceramic centers in all of, were designed specifically for their striking effects on porcelain.

Decoration. Porcelain wares may be decorated under the glaze using pigments that include cobalt and copper or over the glaze using coloured enamels In a discussion of material science, enamel is the colorful result of fusing powdered glass to a substrate by firing, usually between 750 and 850 degrees Celsius. The powder melts and flows and hardens to a smooth, durable vitreous coating on metal, glass or ceramic. According to some sources, the word enamel comes from the High German word. Like many earlier wares, modern porcelains are often bisque Bisque, also called biscuit, is a fired piece of unglazed ceramic ware. Depending on the technique and materials used, it is either the final article, such as bisque dolls, or an intermediary stage before the article has a coating of glaze applied and is then fired again-fired at around 1,000 degrees Celsius Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale two years before his death. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature interval (a difference between two temperatures, coated with glaze and then sent for a second glaze-firing at a temperature of about 1,300 degrees Celsius or greater. Another early method is once-fired where the glaze is applied to the unfired body and the two fired together in a single operation.

Firing. In this process, green (unfired) ceramic wares are heated to high temperatures in a kiln to permanently set their shapes. Porcelain is fired at a higher temperature than earthenware so that the body can vitrify and become non-porous.

Categories of porcelain

Porcelain can be divided into the three main categories: hard-paste, soft-paste, and bone, depending on the composition of the paste, the material used to form the body of a porcelain object.

Hard paste

Main article Hard-paste porcelain

Some of the earliest European porcelains were produced at the Meissen factory in the early 18th century; they were formed from a paste composed of kaolinite, quartz, and alabaster and fired at temperatures in excess of 1,350 °C (2,462 °F), producing a porcelain of great hardness and strength. Later, the composition of the Meissen hard paste was changed and the alabaster was replaced by feldspar, allowing the pieces to be fired at lower temperatures. Kaolinite, feldspar and quartz (or other forms of silica) continue to provide the basic ingredients for most continental European hard-paste porcelains.

Soft paste

Main article Soft-paste porcelain

Its history dates from the early attempts by European potters to replicate Chinese porcelain by using mixtures of china clay and ground-up glass or frit; soapstone and lime were known to have also been included in some compositions. As these early formulations suffered from high pyroplastic deformation, or slumping in the kiln at raised temperature, they were uneconomic to produce. Formulations were later developed based on kaolin, quartz, feldspars, nepheline syenite and other feldspathic rocks. These were technically superior and continue in production.

Bone china

Main article Bone China

Although originally developed in England to compete with imported porcelain, Bone china is now made worldwide. It has been suggested^{[by whom?]}that a misunderstanding of an account of porcelain manufacture in China given by a Jesuit missionary was responsible for the first attempts to use bone-ash as an ingredient of Western porcelain (in China, china clay was sometimes described as forming the bones of the paste, while the flesh was provided by refined porcelain stone)^{[citation needed]}. For whatever reason, when it was first tried it was found that adding bone-ash to the paste produced a white, strong, translucent porcelain. Traditionally English bone china was made from two parts of bone-ash, one part of china clay kaolin and one part china stone (a feldspathic rock), although this has largely been replaced by feldspars from non-UK sources.^[3]

History

Chinese porcelain

Porcelain is generally believed to have originated in China. Although proto-porcelain wares exist dating from the Shang Dynasty about 1600 BCE, by the Eastern Han Dynasty (100-200 BCE) high firing glazed ceramic wares had developed into porcelain, and porcelain manufactured during the Tang Dynasty period (618–906) was exported to the Islamic world, where it was highly prized.^[4] Early porcelain of this type includes the tri-color glazed porcelain, or sancai wares. Historian S.A.M. Adshead writes that true porcelain items in the restrictive sense that we know them today could be found in dynasties after the Tang,^[5] during the Song, Yuan, Ming, and Qing Dynasties.

By the Sui (about 580 AD) and Tang (about 620 AD) dynasties, porcelain had become widely produced. Eventually, porcelain and the expertise required to create it began to spread into other areas; by the seventeenth century, it was being exported to Europe.

Korean and Japanese porcelain also have long histories and distinct artistic traditions.

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