Diffiniadau o Dermau a ddefnyddir mewn Cerameg

• biscuit

  Biscuit or bisque firing – initial firing usually to allow the ware to be decorated before the second firing.

• bisque

  See Biscuit

• black pottery

  one of the most common forms of traditional pottery where the pots are turned black by cutting out the oxygen at the end of the firing. In an open firing this is done by smothering the fire with fine dung, or damp grass and then possibly pieces of metal sheeting. Sometimes the pots are taken out of the fire or kiln and plunged into grass, sawdust or dung. Black pottery is to be found in many places in Africa, among Pueblo potters of the USA, in Mexico, Colombia, Denmark and Central Europe.

• blanc-de-chine

  (white of china) white glazed porcelain that was used to model small decorative ceramics and figurines. Such wares were widely imported into Europe from the East after 1700.

• bone china

  ware to which bone ash has been added. It fires at a lower temperature than true porcelain and is used to make mass-produced fine white china.

• bonfiring

  see open-firing

• burnishing

  one of the most common finishes on traditional pottery, especially that made by women. The surface polishing seals the outside of the vessel and makes it smooth to touch. This is usually achieved with a hard river pebble. The burnishing stone is the woman potter’s most distinctive tool. Such stones are found in ancient burials and in modern times are frequently passed on from generation to generation.

• celadon

  a pale grey-green to grey-blue glaze used for stoneware and porcelain. The glaze was first used in China and is especially associated with the Sung Dynasty. The colour is created by a small amount of iron oxide. It is translucent and is often combined with a carved decoration which shows through the glaze.

• coiling

  coiling a system of forming used widely by potters in many parts of the world either to make the whole or part of a pot. The potter rolls sausages of clay which are then wound round and smoothed down to create the shape.

• decal

  see transfer print

• domestic ware

  ceramics produced for use in the home such as cups, saucers, bowls, casseroles and teapots.

• earthenware

  a form of pottery fired at a low temperature 500- 1000 degrees C. It normally has a red or brown colour, is relatively porous and is used widely for domestic pottery. It is rendered non-porous by glazing in a second firing.

• extrude

  a system used to create long pieces of shaped clay for handles, for example. Clay is fed into the top and pressed through a shaped tube

• functional pottery

  pottery made for use rather than decoration. It includes domestic ware but also such things as water jars and cooking pots.

• glaze

  fine ground solution of minerals that is used to cover pottery. Pieces are dipped in glaze or it can be sprayed or painted on. It fuses on to the surface during firing to create a matt or glossy non-porous surface.

• grog

  crushed fired clay added to unfired clay to reduce shrinking and add stability during firing. It can also be used to create texture.

• handbuilding

  general word for all forms of making pottery by simple forming systems such as thumb pots, coiling or pulling up from a mound of clay.

• kiln

  a furnace or oven used to bake pottery. Most kilns separate the fuel from the pottery. Modern kilns can be fuelled by electricity or gas but traditionally wood was used.

• maker

  a word that is increasingly used for a person who works in the applied arts such as ceramics, textiles, metalwork etc. It attempts to distance itself from the more loaded designations of craftsperson or artist.

• modelling

  the plasticity of clay means that it is one of the most ancient materials used to model forms by hand.

• mould

  system of making clay objects by pressing a sheet of clay over or into a shape usually made of fired clay or plaster. This may be a vessel form or a figurine.

• porcelain

  a ceramic body which contains kaolin or china clay and must be fired to a high temperature (1300-1450 degrees C) giving a hard, white, translucent finish. First developed in China it is traditionally the most difficult body to work with although in recent years it has been used much more widely by studio potters.

• press-mould

  a plaster or clay mould used to form ceramics especially figurines, bowls and plates. A slab of clay is pressed into or onto the mould. When the clay begins to dry out it takes on the form and can be removed easily from the mould. Complicated forms can involve several moulds.

• raw glaze

  Awaiting description

• roulette wheel

  a tool with a notched or carved wheel on the end of a handle. The wheel is pushed over the clay to make a line of relief pattern. It is used to give simple decorative effects especially at points where two different parts of the pot are joined such as the body and the neck.

• salt glaze

  one of Germany’s major contributions of ceramics. It was produced in Germany as early as the fifteenth century In Britain its first use is recorded in the late seventeenth century. Salt Glaze is a thin glaze achieved by introducing common salt (NaCl) into the kiln at high temperature. The chlorine goes up the chimney as a gas and the sodium combines with the silica in the clay body to create a thin, glassy film on the surface of the ware. The texture is often finely dotted or mottled, not unlike orange peel. The technique has been very popular with studio potters.

• slab building

  making a form from slabs of rolled out clay.

• slip

  a system of making ceramics from a mould of clay or more commonly plaster. The casting slip is poured into the mould and as the water is absorbed by the plaster the clay dries out into the shape.

• slip casting

  a system of making ceramics from a mould of clay or more commonly plaster. The casting slip is poured into the mould and as the water is absorbed by the plaster the clay dries out into the shape.

• sponge decoration

  Sponge decoration: inexpensive system of decoration using small sponges, sometimes cut into simple shapes and dipped in coloured glaze or slip and then dabbed on the surface.

• stoneware

  Stoneware: a strong hard body fired to around 1200 degrees C. It is usually brown or grey coloured and was used widely for functional pottery such as jars and drinking flasks. The subtle muted glaze effects have been much prized by studio potters in the 20th century.

• studiopottery

  Studio pottery: ceramics produced by individual makers usually trained in art school rather than learning as artisan potters in a family business. Studio pottery is a practice dating from the early 20th century and makers normally sign their work. Studio pottery often implies vessels of some kind but can extend to figurative pieces. Many practitioners now prefer to identify themselves as ceramist or ceramic artist or they use the more neutral word for craftsperson – maker.

• temper

  material added to unfired clay to open up the body, reduce shrinkage and decrease the effect of thermal shock (stress due to sudden changes of temperature) during firing. Sand, shells, grog, grass or dung are all used depending on availability or tradition.

• terracotta

  (meaning cooked earth) once-fired earthenware which normally takes a red colour.

• throwing

  a system of forming vessels using a potter’s wheel which has a circular turning surface on which the clay is placed. The walls are formed by the centrifugal force of the spinning clay against the hands. The potter’s wheel was developed in the middle east over 5000 years ago.

• transfer print or decal

  A form of ceramic decoration used especially for mass-produced china. The design in ceramic ink or underglaze colours is printed on paper and then applied to the surface of a glazed object and fired to a temperature where the glaze will begin to melt; this will give the appearance of lying beneath the glaze.

• turning

  a process used to trim and finish off pottery, especially objects that have been thrown on a wheel. For example, a piece can be turned upside down on the wheel and the base is trimmed by holding a metal tool against the rim as the wheel revolves.

• wood-firing

  most traditional kilns are fired with wood whereas modern kilns and factory production use coal, gas or electricity. Studio potters in the 20th century revived the art of wood-fired kilns which give interesting and lively surface effects.

• yunomi

  Japanese word for a cup without a handle.