Corning Museum of Glass

The technique whereby glass is removed from the surface of an object by grinding it with rotating wheels made of stone, wood, and cork. 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.

A blob of glass applied to a glass object primarily as decoration, but also to afford a firm grip in the absence of a handle.

An atmosphere in a kiln or furnace that is deficient in oxygen. Sometimes, a reducing atmosphere is created deliberately to reduce oxides to their metallic state, as in the case of luster pigments.

An enclosed structure for the production and application of heat. In glassmaking, furnaces are used for melting the batch, maintaining pots of glass in a molten state, and reheating partly formed objects at the glory hole.

(1) A shiny metallic effect made by painting the surface with metallic oxides that have been dissolved in acid and mixed with an oily medium. Firing in oxygen- free conditions at a temperature of about 1150°F (600°C) causes the metal to deposit in a thin film that, after cleaning, has a distinctive shiny surface. Strictly speaking, this process is a form of staining. (2) A glass lighting device, such as a candelabrum or candlestick, decorated with hanging prismatic drops.

An oven used to process a substance by burning, drying, or heating. In contemporary glassworking, kilns are used to fuse enamel and for kiln-forming processes such as slumping.

The application of a layer of glass over a layer of contrasting color. The gaffer either gathers one layer over another gather, or inflates a gob of hot glass inside a preformed blank of another color. The two components adhere and are inflated together (perhaps with frequent reheating) until they have the desired form. Sometimes, the upper layer is carved, cut, or acid-etched to produce cameo glass.

A substance, usually clay with a high silica content, capable of resisting high temperatures. Furnaces and pots are made from refractory materials.

Silicon dioxide, a mineral that is the main ingredient of glass. The most common form of silica used in glassmaking has always been sand.

A fire-clay container in which batch is fused and kept molten. The glassworker gathers glass directly from the pot.

(German, “beaker”) A large cylindrical beaker, usually with enameled decoration, made in Germany, Bohemia, and Silesia between the 16th and 18th centuries, and used mainly for drinking beer.

The process of removing glass or imparting a matte finish by bombardment with fine grains of sand that are propelled by compressed air.

The process of etching the surface of glass with hydrofluoric acid. Acid-etched decoration is produced by covering the glass with an acid-resistant substance such as wax, through which the design is scratched. The object is then immersed in hydrofluoric acid, or a mixture of dilute hydrofluoric acid and potassium fluoride is applied to etch the exposed areas of glass. Acid etching was first developed on a commercial scale by Richardson’s of Stourbridge, England, which registered a patent in 1857. An effect superficially similar to weathering can be obtained by exposing glass to fumes of hydrofluoric acid to make an allover matte surface.

An air-filled void, which may be of almost any shape. Air traps in stems are frequently tearshaped or elongated and spirally twisted.

The technique of forming an object by inflating a gather or gob of molten glass on the end of a blowpipe. Traditionally and in modern furnace working, the gaffer blows through the tube, slightly inflating the gob, which is then manipulated into the required form by swinging it, rolling it on a marver, or shaping it with tools or in a mold. It is then inflated to the desired size. In flameworking, one end of the glass tube is heated and closed immediately, after which the worker blows into the other end and manipulates the hot glass.

A type of decoration in the stems of 18th-century and later drinking glasses, made by twisting a glass rod embedded with threads of white glass, threads of colored glass, columns of air (air twists), or a combination of all three.

The process of cutting into the surface of an annealed glass object either by holding it against a rotating copper wheel fed with an abrasive or by scratching it, usually with a diamond.

A term frequently used to mean all pre-Roman and ancient Roman glass.

(from Greek) A drinking vessel used in many parts of the ancient world. Most ancient glass rhytons are of the Roman period. They are in the form of a horn, sometimes with the head of an animal at the tip. The tip is perforated, and one drank from it by holding the rhyton above one’s head and catching the stream of liquid in the mouth.

(Italian, “glass with a small network”) A type of blown glass made with canes organized in a crisscross pattern to form a fine net, which may contain tiny air traps.

(French, “manner, or style, of Venice”) Glass made in imitation of Venetian products, at centers other than Venice itself. Façon de Venise glass was popular in many parts of Europe in the 16th and 17th centuries.

Objects made from preformed elements placed in a mold and heated until they fuse. The term “mosaic glass” is preferable to “millefiori,” except in the case of Venetian or façon de Venise glass.

(Italian, “glass with a small network”) A type of blown glass made with canes organized in a crisscross pattern to form a fine net, which may contain tiny air traps.

A surface decorated with many small, adjoining pieces of varicolored materials, such as stone or glass.

A strand of glass, roughly circular in section, drawn out from a gather.

A technique of decorating the surface of an object. Copper disks (wheels) of various sizes and rim profiles are rotated on a spindle. An abrasive such as Carborundum (in the past, emery was frequently used), mixed with oil, is applied to the edge of the wheel. The wheel presses the abrasive against the glass so that it removes the surface by grinding.

A process of decorating the surface of glass by the grinding action of a wheel, using disks of various sizes and materials (usually copper, but sometimes stone), and an abrasive in a grease or slurry applied to a wheel, as the engraver holds the object against the underside of the rotating wheel. See also Cutting and Copper-wheel engraving.

Quartz (chemically pure silicon dioxide), which is usually colorless. From earliest times, glassmakers sought to imitate it.

Smoothing the surface of an object when it is cold by holding it against a rotating wheel fed with a fine abrasive such as pumice or cerium oxide. Glass can also be polished with hand-held tools.

A popular term for colorless lead glass, which has a high refractive index and consequently is particularly brilliant. In the United Kingdom, glass described as crystal must contain a defined percentage of lead oxide. Today, the word is often used to describe any fine glass tableware.

A refractory powder that can be mixed with water and applied to shelves in a kiln or to mandrels to prevent glass or glaze from sticking to them. This is also known as bat wash.

Any instrument used by glassworkers to develop and shape an object. Glassworkers’ tools include the blowpipe, pontil, gathering iron, jacks, shears, clapper, pallet, block, pincers, battledore, lipper, and crimper.

A cylindrical object, usually made of wood but sometimes of glass, for rolling out dough or pasta to the required thickness. Many glass rolling pins are friggers, with a knob at each end so that they can be suspended by a cord.

The English term for an object made by a glassworker on his own time. Most friggers were made from the molten glass that remained in the pot at the end of the day. Such glass was considered to be a worker’s perquisite. American glassworkers referred to friggers as “end-of-day” objects. They are also known as whimsies.

A part of the glass that differs in composition from the surrounding matrix. This difference produces a change in the refractive index, which enables the cord to be seen as a streak and so spoils the appearance of the glass.

A drinking vessel with a bowl that rests on a stemmed foot.

The narrow part of a goblet or tazza that separates the bowl and the foot.

A beaker decorated with claw- or trunklike protrusions made by applying blobs of hot glass that melted the parts of the wall to which they were attached. The blobs were then blown outward and manipulated to resemble hollow claws. Claw beakers were made in Europe between the fifth and seventh centuries A.D. Similar decoration was made in Germany in the 16th century.