In glassmaking, a soluble salt consisting mainly of potassium carbonate or sodium carbonate. It is one of the essential ingredients of glass, generally accounting for about 15-20 percent of the batch. The alkali is a flux, which reduces the melting point of the major constituent of glass, silica.

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.

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

(1) Raw glass or pieces of broken glass from a cooled melt, intended for use as an ingredient of batch; (2) scrap glass intended for recycling.

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 mixture of raw materials (often silica, soda or potash, and lime) that is melted in a pot or tank to make glass. Cullet, as well as minor ingredients such as colorants, can be added to the batch to help the melting process.

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.

A large receptacle constructed in a furnace for melting batch. Tanks, which were first used in antiquity, replaced pots in larger glass factories in the 19th century.

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

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 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.

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.

(French, “hammered”) The word used to describe the multifaceted, wheel-engraved surface favored by Emile Gallé (1846-1904), Daum, and others, to create a textured background that resembles beaten metal.

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.

A drinking vessel for wine or beer. It has an ovoid mouth, a cylindrical body, and a conical foot. The body is usually decorated with prunts.

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

A flameworked centerpiece or mantel ornament consisting of a tall fountain with two birds perched on the rim, and two or more shorter pedestals, each with a bird on the top. The birds have tails made of glass fibers. Bird fountains were made in England in the mid-19th century.

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.

(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.

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 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 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.