Related Research Articles
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, and brick.
Pottery is the process and the products of forming vessels and other objects with clay and other raw materials, which are fired at high temperatures to give them a hard and durable form. The place where such wares are made by a potter is also called a pottery. The definition of pottery, used by the ASTM International, is "all fired ceramic wares that contain clay when formed, except technical, structural, and refractory products". End applications include tableware, decorative ware, sanitary ware, and in technology and industry such as electrical insulators and laboratory ware. In art history and archaeology, especially of ancient and prehistoric periods, pottery often means only vessels, and sculpted figurines of the same material are called terracottas.
Raku ware is a type of Japanese pottery traditionally used in Japanese tea ceremonies, most often in the form of chawan tea bowls. It is traditionally characterised by being hand-shaped rather than thrown, fairly porous vessels, which result from low firing temperatures, lead glazes and the removal of pieces from the kiln while still glowing hot. In the traditional Japanese process, the fired raku piece is removed from the hot kiln and is allowed to cool in the open air.
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires.
Earthenware is glazed or unglazed nonvitreous pottery that has normally been fired below 1,200 °C (2,190 °F). 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, and such a process is used for the great majority of modern domestic earthenware. The main other important types of pottery are porcelain, bone china, and stoneware, all fired at high enough temperatures to vitrify. End applications include tableware and decorative ware such as figurines.
Stoneware is a broad term for pottery fired at a relatively high temperature. A modern definition is a vitreous or semi-vitreous ceramic made primarily from stoneware clay or non-refractory fire clay. End applications include tableware, decorative ware such as vases.
Fire clay is a range of refractory clays used in the manufacture of ceramics, especially fire brick. The United States Environmental Protection Agency defines fire clay very generally as a "mineral aggregate composed of hydrous silicates of aluminium (Al2O3·2SiO2·2H2O) with or without free silica."
Salt-glaze or salt glaze pottery is pottery, usually stoneware, with a ceramic glaze of glossy, translucent and slightly orange-peel-like texture which was formed by throwing common salt into the kiln during the higher temperature part of the firing process. Sodium from the salt reacts with silica in the clay body to form a glassy coating of sodium silicate. The glaze may be colourless or may be coloured various shades of brown, blue, or purple.
A saggar is a type of kiln furniture. It is a ceramic boxlike container used in the firing of pottery to enclose or protect ware being fired inside a kiln. The name may be a contraction of the word safeguard.
Egyptian faience is a sintered-quartz ceramic material from Ancient Egypt. The sintering process "covered [the material] with a true vitreous coating" as the quartz underwent vitrification, creating a bright lustre of various colours "usually in a transparent blue or green isotropic glass". Its name in the Ancient Egyptian language was tjehenet, and modern archeological terms for it include sintered quartz, glazed frit, and glazed composition. Tjehenet is distinct from the crystalline pigment Egyptian blue, for which it has sometimes incorrectly been used as a synonym.
Architectural terracotta refers to a fired mixture of clay and water that can be used in a non-structural, semi-structural, or structural capacity on the exterior or interior of a building. Terracotta is an ancient building material that translates from Latin as "baked earth". Some architectural terracotta is stronger than stoneware. It can be unglazed, painted, slip glazed, or glazed.
Glaze defects are any flaws in the surface quality of a ceramic glaze, its physical structure or its interaction with the body.
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 components insoluble by causing them to combine with silica and other added oxides. However, not all glass that is fused and quenched in water is frit, as this method of cooling down very hot glass is also widely used in glass manufacture.
A slip is a clay slurry used to produce pottery and other ceramic wares. Liquified clay, in which there is no fixed ratio of water and clay, is called slip or clay slurry which is used either for joining leather-hard (semi-hardened) clay body together by slipcasting with mould, glazing or decorating the pottery by painting or dipping the pottery with slip. Pottery on which slip has been applied either for glazing or decoration is called slipware.
This is a list of pottery and ceramic terms.
The room-temperature form of quartz, α-quartz, undergoes a reversible change in crystal structure at 573 °C to form β-quartz. This phenomenon is called an inversion, and for the α to β quartz inversion is accompanied by a linear expansion of 0.45%. This inversion can lead to cracking of ceramic ware if cooling occurs too quickly through the inversion temperature. This is called dunting, and the resultant faults are known as dunts. To avoid such thermal shock faults, cooling rates not exceeding 50 °C/hour have been recommended.
Pottery fracture results from stress within a ceramic body due to thermal expansion and contraction, shrinkage, and other forces. Poor drying or uneven compression and alignment of particles can result in low strength. Cracking may appear in greenware as well as each stage of the firing including bisqueware and glazed ware.
Conservation and restoration of ceramic objects is a process dedicated to the preservation and protection of objects of historical and personal value made from ceramic. Typically, this activity of conservation-restoration is undertaken by a conservator-restorer, especially when dealing with an object of cultural heritage. Ceramics are created from a production of coatings of inorganic, nonmetallic materials using heating and cooling to create a glaze. These coatings are often permanent and sustainable for utilitarian and decorative purposes. The cleaning, handling, storage, and in general treatment of ceramics is consistent with that of glass because they are made of similar oxygen-rich components, such as silicates. In conservation ceramics are broken down into three groups: unfired clay, earthenware or terracotta, and stoneware and porcelain.
Biscuit refers to any pottery that has been fired in a kiln without a ceramic glaze. This can be a final product such as biscuit porcelain or unglazed earthenware or, most commonly, an intermediate stage in a glazed final product.
Kiln furniture are devices and implements inside furnaces used during the heating of manufactured individual pieces, such as pottery or other ceramic or metal components. Kiln furniture is made of refractory materials, i.e., materials that withstand high temperatures without deformation. Kiln furniture can account for up to 80% of the mass of a kiln charge.
References
- ↑ "Standard Terminology of Ceramic Whitewares and Related Products." ASTM C242-01. ASTM International.
- ↑ "Dictionary of Ceramics", Third edition. A.Dodd A. D.Murfin. Institute of Materials. 1994. ISBN 0-901716-56-1
- ↑ "Dunting Temperature Measurement." K.Marshall, W.Roberts. British Ceramic Research Association. TN 143.1969.
- ↑ "Dictionary of Ceramics", Third edition. A.Dodd A. D.Murfin. Institute of Materials. 1994. ISBN 0-901716-56-1
- ↑ "Dunting - A Serious Problem Of Ceramics Industry." S.K.Mukherji. Indian Ceramics. 27, (2), 36, 1984.
- ↑ "Quartz V Flint. Pt.2. Aspects Related To Refire Dunting." K.Marshall, W.Roberts. British Ceramic Research Association. TN 141 Pt.2. 1969.
- ↑ "Clay Materials - For the self reliant potter", Henrik Norske. GTZ 1990; 98 pages