A concavity in the base of a vessel, usually made by depressing the base with a tool. The provision of a kick strengthens the bottom of the vessel and reduces the vessel’s capacity.

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

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.

(corruption of “grandfather”) The master craftsman in charge of a chair, or team, of hot-glass workers.

(1) A hole in the side of a glass furnace, used to reheat glass that is being fashioned or decorated; (2) a separate appliance for reheating glass.

The process of pulling semimolten glass to elongate it. It is used, for example, in the production of canes.

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.

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 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.

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 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.

(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.

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

A type of glass with an iridescent surface, patented by Louis Comfort Tiffany (1848-1933) in 1894.

A glass tube, open at both ends, used to shield the flame of an oil lamp, to trap soot, and to increase the draft.

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.

A glassworker’s tool consisting of a square piece of wood or metal and a handle. It is used to flatten the bases of vessels.

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.

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 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.

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 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.

(1) The bench used by the gaffer while forming a glass object. Traditionally, this is a wide bench with arms, on which the gaffer rests the blowpipe with its parison of molten glass and rolls it backward and forward so that the parison retains its symmetrical shape during the forming process. (2) The team of glassworkers who assist a gaffer.

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.

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.

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.

(Noun) A mass of molten glass (sometimes called a gob) collected on the end of a blowpipe, pontil, or gathering iron; (verb) to collect molten glass on the end of a tool.

The technique of removing the surface of an object with a rotating wheel fed with an abrasive, or by some other means.

The fluid glass produced by melting batch.

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.