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Glossary C

CALIPER — Lockable tongs used to measure or reference a size or dimension of a glass piece.
CALCINE — To purify a material through the action of heating to red 700–750 oC (1292-1382 oF)
CAME — Used in leaded or stained glass, came is a thin channeled strip, usually lead but may be other metals such as copper, brass or zinc, that usually has a hollow section on one side, or that has a hollow section on either side of the center of the strip When viewed in a cross section the came is shaped like a U or an H. Came is used to join pieces of art glass together or to form a border around an art glass piece.
CAMEO — An ancient Roman carving technique using multi-layers of glass, with an opaque white outer surface carved by hand or acid etching to create designs by exposing the colored inner layer.
CANE — A thin rod of glass made up of different glass pieces bundled together and fused to form a design that is visible in cross section. Often, it is pulled and twisted. It is also used in glassmaking to produce effects like stripes or twisted filigree.
CARVING — The removal of glass from the surface of an object by means of hand-held tools or sandblasting.
CASED GLASS — Ttwo layers of contrasting glass fused together, creating a single piece, with the inner layer sometimes blown into the outer layer, or a piece of one color dipped into molten glass another color while still hot. Cameo is one form of cased glass.
CASTING — A Generic term for a wide variety of techniques used to form glass in a mold, such as kiln casting and hot casting. Hot casting includes pouring molten glass into a mold or form. Kiln casting involves melting glass in a mold inside a kiln. There are various ways to achieve casting glass. From melting frit (ground glass) to pouring hot molten glass into a mold to achieve a particular shape, each method is unique and different.
CAST FIGURE MOLD — A process perfected by Reuben Haley and used to create his unique Martele hand wrought glassware; a glass mold is cast from a sculpted model to transfer fine details without additional milling.
CATHEDRAL GLASS — A glass that is a single color and that is transparent and monochromatic. A single color sheet glass, with smooth or textured surfaces.
CATSPAW — (Single Roll forming method.) A surface texture resulting from the chilling of hot glass on a cool table. The appearance is likened to the paw prints of a cat.
CELADON — Celadon refers both to ceramics of a bluish/pale sea-green color and the Chinese and Korean porcelain and stoneware from which this type of ware originated.
CERAMIC FIBER (INSULATION) — A refractory material that is made from spun fibers.
CERAMIC CHANGE — The slow process of clay becoming ceramic. Clay which is exposed to heat 600oC / 1112oF, losses its chemically bound water molecules and can no longer be broken down by water. Once this change has occurred it cannot be reversed.
CERAMICS — Derived from the Greek keramikos, meaning "of pottery." It can refer to the craft of making decorative and/or functional objects from fire-hardened clay, or to the objects themselves. Ceramics is a broader term than pottery, as it also refers to porcelain and other objects made from materials that permanently change when heated.
CHAP STICK/BEES WAX — Used to protect marks that are made on glass. This protection will keep the mark in place when grinding or using a glass saw.
CHARGE — The act of filling the furnace with batch.
CHINA — High quality porcelain.
CHUCK — Chucks are hollow, open-ended cylinders of varying size that are used to support an upside-down pot on the potter's wheel so that the pot bottom can be easily trimmed - a task that's often overlooked by beginning or less skillful potters.
CHIP MOLD — A glass mold technique in which a pattern is cut or chipped with hammer and chisel into an iron mold’s surface.
CIRCLE CUTTER — Scores ovals and circles on flat glass. It typically has a suction cup that secures the cutter to the glass. Similar to a compass with a glass cutter attached.
CLAY — The decomposition of Granite through the process of Kaolinization creates clay. There are three primary clay groups - kaolinite, smectite, and illite - and about 30 different types of so-called "pure" clays.
CLAY BODY — A clay designed for a special purpose. It is created by blending different clays and by mixing clays with other materials, such as feldspar and flint in order to produce a desired workability, maturing temperature, or finished result. A clay body is the result of human design, and is not naturally made.
COBALT — One of the strongest metal oxides used to color glass or glazes. Cobalt creates a dark dense royal blue in most cases. Historically used in China as a painting pigment on Blue and White wares.
COBBLESTONE — Cobblestone is a unique texture similar to hammer-back glass, but with a lower profile. Cobblestone is reminiscent of old style glasses of an era gone by. It is very mild in texture, barely obscuring the light as it passes through. Cobblestone is frequently used in the United Kingdom in pubs and restaurants.
C.O.E. (COEFFICIENT OF EXPANSION) — A number that indicates the rate of expansion, per degree of temperature increase, of glass as it is heated. The measured expansion of heated glass based on the percentage of change of a glass rod heated one degree centigrade. Used to help determine compatibility of different glasses for the fusing process. COE is a term frequently used by fusers and glass casters because only glass with close to the same COE can be successfully fused together. If glasses with different COE’s are mixed, the glass is said to be incompatible and will not fuse properly.
COILING — A method of hand building a form using long rolled out, or extruded, snake-like lengths of clay. Each coil of clay is integrated with the previous one to build the work up. The coils may be completely obliterated in the construction process or retained for their decorative qualities.
COLD COMBING — The process of achieving the look of hot combed surface without working inside a hot kiln.
COLD WORKING — Working with or changing glass in its cold, natural state. This could involve sanding, grinding, drilling, or sandblasting. Refers to a variety of polishing, grinding, cutting and engraving techniques that are executed (usually in a Cold Shop) after glass objects have been formed, fully annealed and cooled. Many coldworking techniques include the use of rotary machinery fed with water and abrasives, or hand-held tools.
COLLAR — Section added to a kiln for additional height.
COMBING — Process in which a rake-like tool is drawn across molten glass to create artistic patterns. The glass is heated to a liquid state and is manipulated by pulling or "combing" a blunt point through the surface. Also used in glass blowing.
COMPATIBILITY — Glasses are said to be compatible if, after being fused together by blowing or kiln forming and properly annealed, they remain relatively free from internal stress. (See Coefficient of Expansion.)
CONFETTI — Wafer thin pieces of irregularly shaped glass, usually smaller than 6mm in diameter that are used for creating designs in glass. Larger pieces are called Eggshells.Thin shard of glass used to add shading and design. Also referred to as shards. Confetti is made by blowing a bubble of glass and then breaking it into shards.
CONES — Pyrometric cones are composed of clay and glaze material, designed to melt and bend at specific temperatures. By observing them through a small 'Peep Hole' in the kiln it is possible to ascertain the exact conditions in the kiln. Cones are an excellent indicator of true temperature ranges as the degree of glaze melt is a combination of time and temperature (“heat work”), thus a fast firing needs to go to a higher temperature to get the same results as a slow firing to a lower temperature. Used in a kiln, a pyrometric cone deforms when the proper heat work is achieved. Various cones are made to either trigger mechanical shut off (Kiln Sitter ) or to act as a witness to kiln conditions. Pottery cones are numbered from 022 (coolest) to 42 (hottest), e.g. bisque firing is usually done between cones 08 and 06, equivalent to a temperature range of 1720 degrees Fahrenheit to 1835 degrees Fahrenheit.
CONE HOLDER — Needed for support by some pyrometric witness cones.
CONTROLLER — The switch on a kiln that allows you to turn it on or off, with different positions in between for heating rates. It could be manual or digital.
COPPER FOIL — Thin, narrow strips of adhesive-backed copper tape is used to wrap the edges of glass pieces that have been cut to fit a pattern. Once wrapped, solder is applied, bonding the glass pieces together. Assembling a stained glass project in this manner is called the “copper foil technique.” Louis Tiffany is credited with its development.
CORD — Accidental, colorless streaks in the glass caused by local differences in refractive indexes. Often caused by poor mixing of the batch.
CORE FORMING — The technique of forming a vessel by winding, trailing or gathering molten glass around a core form supported by a stake rod or mandrel. After the forming process, the glass object is annealed, then removed from the mandrel and the core is scraped clean.
CRACKING OFF — The process of detaching the unwanted portion of the glass/punty from the blowpipe and the intended rim.
CRACKLE/CRAZING — Refers to the forming of very fine cracks in the glaze of a fired pot. This occurs during the cooling process because, if not properly matched with the clay body, the glaze shrinks more than the clay as it changes from a liquid to a solid state. Crackling is done intentionally to create decorative rather than functional pottery. Crackling is especially common in Raku pottery. Small hairline cracks in glass or glazed surfaces, also called Iced Glass, a mold or hand blown glass object, while hot, is plunged into cold water before blowing to produce a finely crackled outer surface and smooth interior.

CRASH COOLING — The act of opening the kiln after firing to release heat and freeze the project to keep it from fusing further.
CRYSTALLINE GLAZE — Most glazes have no easily visible crystal structure. Crystalline glazes have large and dramatic crystals up to about three inches across. A high alkaline low alummina glaze is vital for crystals to develop. Additions of zinc and titanium also help seed the crystals. An extremely slow cool of the kiln is necessary, to allow the crystals to grow. Because of the low alumina content in crystalline glazes they are very runny, often pots are supported in the kiln on stilts to avoid them adhering to the kiln shelves, the stilts can be broken off after the firing.
CRATERING — Ceramic term. Broken bubbles in glazed surfaces. Usually indicates underfiring.
CRANBERRY — transparent, reddish-pink color of glass, produced by adding gold oxide to a batch, originated in the 1820s and popular through the 1880s.
CRIMPING — decorative ruffle or ribbon design around the rim of a vase or bowl, achieved by manipulating the shape with a tool while the piece is still hot.
CRUCIBLE —A high temperature, pot-shaped container used to melt glass in furnaces or kilns.
CRYSTAL— Popular term for colorless lead glass that has a high refractive index and, consequently, is particularly brilliant. Often used to describe any fine glass tableware.
CULLET — Raw glass, or pieces of broken glass from a cooled melt. These scraps are generally intended for recycling.
CUTTER — A glass cutter. This is a tool consisting of a handle and a beveled cutting wheel.
CUTTER OIL — A high-viscosity fluid used with a glass cutter. The oil keeps the wheel clean of dust and glass chips, which increases the life of the cutter.
CUTTING — The technique whereby glass is removed from the surface of an object. The first stage of the process employs a stone wheel under a continuous stream of water. Later, wheels of fine-grained stone and wood, fed with various abrasives, are used to grind and polish the surface.
CUSTARD GLASS — an opaque milk glass variation in colors varying from rich, creamy yellow to bone white with an opalescent finish; Uranium salts were added to batches used to produce antique custard glass, so that it will trigger a Geiger counter needle to move and also glows under a black light.
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