Ceramic glossary

  • Ball Clay.-A natural clay which is the most plastic of all clays. Often mixed with other clays to make them more plastic.
  • Bat.-A plaster of Paris slab, used to absorb moisture from wet clay. See part II, lesson VIII.
  • Blanks.-China ware and tiles fired with a white glaze, upon which overglazes are often applied.
  • Bisque.-Biscuit, terra cotta-unglazed clay fired until chemical water is driven off.
  • Body.-Clay which is ready for use, raw or compounded.
  • Bone Dry.-Unfired clay which has been air dried to the maximum at room temperature.
  • Bone China.-China ware in which ashes of calcined bones are added to the clay body to increase translucency of the china.
  • Calcined.-Made powdery by the action of heat.
  • Casting.-The process of making reproductions with clay slip in plaster of Paris molds.
  • Ceramics.-Art of creating and making fired clay objects.
  • China Stone.-Petuntze; one of the major ingredients of porcelain, which gives it translucency and acts as a flux in firing.
  • China Painting.-The painting on china with overglaze colours.
  • Dipping.-A method of applying glaze to ceramic objects, by dipping into a bucket or pot of liquid glaze.
  • Earthenware.-A coarser heavier type of clay ware, glazed or unglazed, pertaining to utility ware and generally undecorated.
  • Clay Body.-The clay from which the ceramic object is made.
  • Coil Method.-A procedure for making clay objects from plastic clay coils or snakes.
  • Compounded Clay.-Clay body which is made by blending several clays and minerals together, as opposed to clay found in the natural state.
  • Cones.-Pyrometric pyramids used to determine maturity during firing.
  • Consistency.-The degree of firmness, density, viscosity, plasticity, etc.
  • Covering Quality.-The degree with which a glaze obscures the clay or other glazes beneath it.
  • Cracked.-The position of the kiln door when barely open.
  • Crazing.-The effect of crackle glazes; tiny fracturing of the glaze surface.
  • Curing.-The process of permitting moist clay to rest until it attains a uniform moisture density throughout.
  • Decorating Wheel.-A rotating device upon which objects to be decorated can be placed to assist the decorator.
  • Delft.-Types of English and Dutch ware which employ opaque tin and lead glazes, generally using shades of cobalt blue colour decoration.
  • Drain.-The act of removing the excess slip from a mould during casting. See lesson VII.
  • Dresden China.-Porcelain china from Dresden where the first true porcelain was made in Europe.
  • Embossing.-Placing a raised clay decoration on the surface of a ceramic object-such as in certain types of Wedgwood ware.
  • Enamel.-A highly glossy, highly covering glaze.
  • Engobe.-A clay slip generally used for slip painting or covering the clay body beneath. See lesson X.
  • Faience.-A type of ceramic ware originally made in Faenza, Italy, and later made in France. Like Delft it employs a lead-tin opaque covering glaze.
  • Feldspar.-A constituent of crystalline rock comprising aluminium silicates with potassium, sodium, calcium or barium. When decomposed it becomes Koalin.
  • Firing.-The act of applying heat to ceramic ware.
  • Firing Cycle.-The period from when heat is first applied in a kiln until the fired ware has completely cooled and is ready to be removed from the kiln.
  • Flint.-A very hard kind of quartz.
  • Flood Mould.-A one-piece mould. See lesson VII.
  • Flux.-A substance which assists in the melting of metals or minerals when heat is applied.
  • Frit.-Pulverized glass of various kinds.
  • Fuse.-Liquefy or melt by heat.
  • Gate.-Opening in an assembled mould through which casting slip is poured into the mould cavity, through which the air escapes, and through which the excess slip is drained off.
  • Green Ware.-Unfired clay either in leather hard or bone-dry condition.
  • Grog.-Crushed bisque; used sometimes in larger clay objects to prevent warping when fired.
  • Gum.-A solution of gum Arabic or tragacanth used to hold underglaze colours in place until fired.
  • Gypsum.-Hydrous calcium sulphate which, when calcined, forms plaster of Paris.
  • Incising.-The act of cutting into with a sharp instrument, as in carving and engraving.
  • Keys.-The mounds and depressions in opposing faces of mould pieces which fit together exactly, retain, and insure the proper position of the pieces.
  • Kick Wheel.-A type of potter's wheel which is rotated by applying the foot against the fly wheel.
  • Kiln.-An oven in which ceramic ware is fired.
  • Kiln Wash.-A slip made of pulverized koalin and flint and applied to kiln floors and kiln furniture when firing glazed ware.
  • Koalin.-One of the principle ingredients of porcelain clay.
  • Leather Hard.-Condition of moist clay when sufficiently dry to be no longer plastic.
  • Luster.-Metallic overglaze which, when fired, forms a thin metal sheen or gloss.
  • Majolica.-A type of ceramic pottery developed in Italy during the Renaissance, with high glossy glaze; a type of opaque glaze with high gloss.
  • Maturing.-The temperature at which particular clays and glazes attain their desired quality and appearance.
  • Matt Glaze.-A type of glaze which is nonglossy, satiny in appearance, and feels like suede leather.
  • Model.-The object from which reproductions are duplicated, or from which plaster of Paris molds are made.
  • Mould.-An assembly of plaster of Paris pieces containing a cavity in which castings are formed.
  • Mould Marks.-Ridges formed on castings where clay slip has run into the seams where two pieces of the mould come together.
  • Muflie.-The walls of a type of kiln which prevent the open flame from coming in contact with stacked ware.
  • Overglazes.-Ceramic colours or lusters which are applied over glazed surfaces for decorative effects, and fired thereon.
  • Plaster of Paris.-Calcined gypsum used in making molds, bats, and models.
  • Plastic.-A condition of moist clay during which it can be easily modelled by hand, but will retain its shape without collapsing.
  • Polychrome.--Multicoloured; may pertain to a type of engobe decoration.
  • Porcelain.-A high firing, hard, translucent, fine texture china, comprising fusible petuntze and nonfusible koalin; the finest ceramic clay body known.
  • Potters' Wheel.-A rotating device upon which plastic clay objects are formed by hand.
  • Pottery.-Fired objects made from raw clays.
  • Pressing.-A method of working plastic clay by forming around a model.
  • Press Mould.-A type of open mould into which plastic clay is pressed to form it in the desired shape. See lesson VIII.
  • Pouring.-The putting of slip into a plaster of Paris mould.
  • Proving Colours.-The application of underglaze, glaze, and overglaze colours on tiles, and firing to maturity to establish the true final colours, prior to their use on other ceramic ware.
  • Raw Clay.-An unblended or noncompounded clay; as found in the natural state.
  • Refractory.-Difficult to fuse, heat resistant.
  • Sagger.-A fire clay box in which ware is stacked and sealed to avoid contact with flame in open flame kilns.
  • Salt Glaze.-A rough, thin transparent glaze caused by volatilizing salt in the kiln, which salt deposits itself on the ware as a glaze upon cooling.
  • Separator.-Moist brown soap film applied to a model to prevent adhesion of plaster of Paris formed around it; and to facilitate the removal of the model from its mould.
  • Sgraffito.-A type of engobe decoration. See lesson X.
  • Sevres.-A fine type of French ceramic ware.
  • Slip.-A liquid consisting of clay suspended in water.
  • Slip Painting.-The painting of engobe on clay objects. See lesson X.
  • Slip Pasting.-A procedure by which plastic and/or leather hard pieces of clay are caused to adhere, using clay slip as the adhesive.
  • Soft Paste.-Chinese soft paste is porcelain to which soap stone is added to lower its maturing temperature. English soft paste is bone china. European soft paste was made in an attempt to imitate the translucency of porcelain by adding frit. Soft pastes are all low firing bodies.
  • Spare.-The part of a clay casting, formed in the gate of a mould, which is cut away after pieces of the mould are removed.
  • Splice.-A method of joining coils, snakes, or other pieces of plastic clay.
  • Stacking.-The loading of a kiln with ware to be fired.
  • Staffordshire.-A well-known type of English ceramic, ware.
  • Stilt.-A type of kiln furniture for supporting ware to be fired.
  • Stoneware.-A high firing, hard, nonporous coarse type of ware, of grey or brownish colour.
  • Tactile.-Pertaining to the sense of touch.
  • Thermal Shock.-The result of a too sudden rise or fall in temperature on ceramic ware.
  • Throwing.-The process of forming objects on a potter's wheel.
  • Triangle.-A type of kiln furniture.
  • Turning.-A process of cutting the surface of thrown objects with scrapers, to a fine finish.
  • Undercut.-A portion of the model which folds in or under. in such a way that if plaster of Paris is formed on it, the plaster mould cannot be removed without damage either to the model or mould.
  • Underglaze.-Concentrated stains used for decoration which are applied to green ware or bisque before glazing. See lesson XI.
  • Vitreous.-Glassy or glasslike.
  • Vitrify.-To change into glass or a glasslike substance by the application of heat to fusion.
  • Wedgwood.-A fine type of English ceramic ware characterized by the use of finely designed, embossed, or bas relief, classical, clay decoration on stained bisque bodies.
  • Wedging.-The process of kneading or working plastic clay until it has a uniform consistency throughout, and is free of air bubbles or pockets. Also, the process of working one piece of plastic clay into another piece. See lesson I.
  • Wetting Agent.-Water glass used in casting slip to reduce the amount of water necessary for proper slip consistency.

Ceramics:
  • Index
  • Coil method
  • Decoration
  • Glaze decoration
  • Glossary
  • Hand pressing
  • Kiln & firing
  • Mould making
  • Plastic & flower
  • Potters wheel
  • Slab method
  • Slip casting

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