A movement that began in the United States in the 1960s and has spread all over the world. It is characterized by the proliferation of glass artists who are not affiliated with factories, but work with hot glass in their own studios. The emergence of independent glass artists was made possible by Harvey Littleton and Dominick Labino’s development in 1962 of a small furnace and easy-to-melt glass.

A term popularized in the 1960s for unique or limited-edition objects designed and made in a studio rather than a factory, often, but not necessarily, by the same person.

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.

A volcanic mineral that was the first form of natural glass used by humans. It is usually black, but it can also be very dark red or green; its splinters are often transparent or translucent.

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

The most common form of silica used in making glass. It is collected from the seashore or, preferably, from deposits that have fewer impurities. For most present-day glassmaking, sand must have a low iron content. Before being used in a batch, it is thoroughly washed, heated to remove carbonaceous matter, and screened to obtain uniformly small grains.

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

The technique of forming a vessel by winding or gathering molten glass around a core supported by a rod. After forming, the object is removed from the rod and annealed. After annealing, the core is removed by scraping.

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.

The generic name for a wide variety of techniques used to form glass in a mold.

Any object embedded in the surface of a larger object.

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

(1) The process of founding or melting the batch; (2) heating pieces of glass in a kiln or furnace until they bond (see Casting and Kiln forming); (3) heating enameled glasses until the enamel bonds with the surface of the object.

A form used for shaping and/ or decorating molten glass. Some molds (e.g., dip molds) impart a pattern to the parison, which is then withdrawn, and blown and tooled to the desired shape and size; other molds (sometimes known as full-size molds) are used to give the object its final form, with or without decoration. Dip molds consist of a single part and are usually shaped like beakers. Full-size molds usually have two or more parts and can be opened to extract the object. Nowadays, most molds are made of metal, but stone, wood, plaster, and earthenware molds were used in the past and are still occasionally employed today.

Sodium carbonate. Soda (or alternatively potash) is commonly used as the alkali ingredient of glass. It serves as a flux to reduce the fusion point of the silica when the batch is melted.

(1) A rounded, hollow vessel; (2) the uppermost part of a goblet, tazza, or wineglass.

A monochrome segment of glass cut from a trail.

Calcined limestone, which, added to batch in small quantities, gives stability. Before the 17th century, when its beneficial effects became known, lime was introduced fortuitously as an impurity in the raw materials. The addition of insufficient lime can cause crizzling.

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 type of decoration that consists of trails applied in sinuous patterns. It was made by the Romans between the second and fourth centuries A.D.

The term applied to several types of Hellenistic and ancient Roman glass objects decorated with designs cut and/or engraved in gold leaf, which is sandwiched between two fused layers of glass. Hellenistic gold glass was made by sandwiching the decoration between two closely fitting cast, ground, and polished vessels, which were then fused. Many Roman gold glasses apparently were made by applying the gold leaf to the surface of an object, reheating it, and inflating a parison against the decorated surface.

Glass of one color covered, usually by casing, with one or more layers of contrasting color(s). The outer layers are acid-etched, carved, cut, or engraved to produce a design that stands out from the background. The first cameo glasses were made by the ancient Romans. The genre was revived in England and, to a lesser extent, in America in the late 19th century.

The process of slowly cooling a completed object in an auxiliary part of the glass furnace, or in a separate furnace. This is an integral part of glassmaking because if a hot glass object is allowed to cool too quickly, it will be highly strained by the time it reaches room temperature; indeed, it may break, either as it cools or at some later date. Highly strained glasses break easily if subjected to mechanical or thermal shock.

The technique of decorating hot glass by dropping onto the surface blobs of molten glass, usually of a different color or colors.

The process of applying trails of glass as decoration on the body, handle, or foot of a vessel. It is done by laying or winding softened threads on a glass object during manufacture.

An iron or steel tube, usually four to five feet long, for blowing glass. Blowpipes have a mouthpiece at one end and are usually fitted at the other end with a metal ring that helps to retain the gather.

A pocket of gas trapped in glass during manufacture. The term is used both for bubbles introduced intentionally (known as air traps or beads) and for unwanted bubbles created during the melting process. Very small bubbles are known as seeds.

The process of decorating glass by the use of gold leaf, gold paint, or gold dust. The gilding can be applied with size, or amalgamated with mercury. It is then usually attached to the glass by heat. Gold leaf can be picked up on a gather of hot glass.

The removal of glass from the surface of an object by means of hand-held tools or sandblasting.

The process of winding a thin trail of glass around an object to create the appearance of parallel lines. In 1876, W. J. Hodgetts of Stourbridge, England, patented a machine that produced very regular and closely spaced threads.

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 container with one handle, used for dispensing liquid.

A mass of molten glass, usually small and freshly gathered from the furnace. In a team of glassworkers, the bit gatherer removes bits from the furnace, using a bit iron. Bits are also known as gobs.

The generic name for decorative windows made of pieces of colored glass fitted into cames and set in iron frames. Strictly speaking, the term is inaccurate because, in addition to glass colored by staining, glaziers used, and continue to use, glass colored throughout by metallic oxide, glass colored by flashing, and glass decorated with enamel.

A stand with a socket or spike for one candle.

Inflating a parison of hot glass in a mold. The glass is forced against the inner surfaces of the mold and assumes its shape, together with any decoration that it bears.

A vitreous substance made of finely powdered glass colored with metallic oxide and suspended in an oily medium for ease of application with a brush. The medium burns away during firing in a low-temperature muffle kiln (about 965°-1300°F or 500°-700°C). Sometimes, several firings are required to fuse the different colors of an elaborately enameled object.

Glass made in the rural glasshouses of central and northern Europe in the late Middle Ages and the early modern period. Most forest glass was fluxed with potash derived from the wood with which the furnaces were fueled. It is green because of iron impurities in the sand from which it was made. The German term for forest glass is Waldglas.

(German, “pole glass”) A tall, narrow cylindrical drinking vessel (hence the name “pole glass”), usually with a pedestal foot.

(German, “cabbage stalk”) A type of beaker with a cup-shaped mouth and a cylindrical or barrelshaped body decorated with prunts, made in Germany between the 15th and 17th centuries. It was the forerunner of the Römer.

(German) A type of drinking glass, similar to a Römer, but with a funnel-shaped mouth. It was made in Germany and the Low Countries in the 16th and 17th centuries.

Glass made in the rural glasshouses of central and northern Europe in the late Middle Ages and the early modern period. Most forest glass was fluxed with potash derived from the wood with which the furnaces were fueled. It is green because of iron impurities in the sand from which it was made. The German term for forest glass is Waldglas.

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.

Potassium carbonate. It is an alternative to soda as a source of alkali in the manufacture of glass.

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

A type of goblet with the stem in the form of a dragon with a convoluted body, outspread wings, open jaws, and a crest. Known in Italian as vetri a serpenti (serpent glasses), dragon-stem goblets were first made in Venice in the 17th century. They were imitated in the Netherlands by producers of façon de Venise glass.

Glass decorated with streaks of two or more colors, resembling marble. Marbled glass was a Venetian specialty from the 15th to 17th centuries, but it was also made in other times and places. Venetian marbled glass is known as calcedonio.

Glass that is colored by (1) impurities in the basic ingredients in the batch or (2) techniques of coloring glass by one of three main processes: (a) using a dissolved metallic oxide to impart a color throughout, (b) forming a dispersion of some substance in a colloidal state, and (c) suspending particles of pigments to form opaque colors.

Glass that resembles an opal, being translucent and white, with a grayish or bluish tinge.

The oxide of a metal. Oxides can be used to color glass and enamel, or to produce lustered or iridized surfaces. The resultant color depends primarily on the oxide used, but it can be affected by the composition of the glass itself and the presence or absence of oxygen in the furnace.

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

(Italian, “chalcedony”) Glass marbled with brown, blue, green, and yellow swirls in imitation of chalcedony and other banded semiprecious stones. Calcedonio was first made in Venice in the late 15th century.

(Italian, “crystal”) A term first used in Venice in the 14th century to describe glass that resembles colorless rock crystal. Most Venetian cristallo, however, has a gray or brownish tint.

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.

Any crystalline inclusion present in glass. Stones consist of unmelted particles of batch, fragments of refractory material from the pot, or devitrification crystals. Stones of the first two varieties are generally irregular but rounded; those of the third variety are angular and well formed.

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

(from Italian, “cup”) An ornamental dish or cup on a stemmed foot. Tazzas were generally made for drinking, for displaying fruit or sweetmeats, and as purely decorative objects.

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

Deep red glass colored by the addition of gold chloride to the batch. The method of making gold ruby glass was perfected by Johann Kunckel (1637-1703) in Potsdam shortly before 1679.

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.

(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.

These terms and their French and Italian equivalents, pâte de verre and pasta vitrea, have been used since at least the 17th century to describe the composition of small objects such as medallions and imitations of precious stones. However, their use to describe such objects is incorrect (they were made with molten glass, sometimes with a high lead content), and they should be restricted to objects of pâte de verre, as described in the next entry.

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.

A bowl for mixing and serving punch. Traditionally, punch was composed of wines or liquors, mixed with hot water or milk, and flavored with sugar, lemons, or spices. Fruit punches, with or without alcohol, are also common.

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 small bottle (in China) or box (in Europe) for powdered tobacco, or snuff. The habit of inhaling snuff, which spread to Europe from the Americas in the 17th century, was introduced to China in the 18th century.

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.

Glassware formed by placing a blob of molten glass in a metal mold and pressing it with a metal plunger or “follower” to form the inside shape. The resultant piece, termed “mold-pressed,” has an interior form independent of the exterior, in contrast to mold-blown glass, whose interior corresponds to the outer form. The process of pressing glass was first mechanized in the United States between 1820 and 1830.

(1) Several types of glass with newly developed surface textures, shaded colors, or casing, made in the United States from about 1870 and in Europe between about 1880 and 1900; (2) more generally, especially when written “art glass,” any ornamental glassware made since the mid-19th century.

A misnomer for English and American lead glass. The term came into use in 1674, when George Ravenscroft’s new glass formula included ground, calcined flint as a source of silica. In the 18th and 19th centuries, the term was applied to decolorized glass, even when it contained no flint.

Any cooled glass object that requires further forming or decoration to be finished.

A small, heavy object designed to hold down loose papers. The first glass paperweights were made in the early 1840s in Venice and France, and their manufacture spread rapidly to other parts of Europe and the United States. Glass paperweights ceased to be fashionable in the early 20th century, but the craft of making them revived in the 1950s.

The technique of forming objects from rods and tubes of glass that, when heated in a flame, become soft and can be manipulated into the desired shape. Formerly, the source of the flame was an oil or paraffin lamp used in conjunction with foot-powered bellows; today, gas-fueled torches are used.

(from French, “new art”) An international late 19th- and early 20th-century decorative style characterized by organic foliate forms, sinuous lines, and non-geometric, “whiplash” curves. Art Nouveau originated in Europe in the late 1880s, and reached the peak of its popularity around 1900. In America, it inspired, among others, Louis Comfort Tiffany (1848-1933). The name is derived from La Maison de l’Art Nouveau, a gallery for interior design that opened in Paris in 1896. The German term for Art Nouveau is Jugendstil.

From French, Exposition Internationale des Arts Décoratifs et Industriels Modernes, an exhibition in Paris in 1925. A style of design that originated in the 1920s and was popular in western Europe and the United States in the 1930s. Art Deco is distinguished by simple, streamlined shapes and frequently by nonrepresentational motifs.

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.