Corning Museum of Glass

A type of English drinking glass of the late 17th and 18th centuries, with the stem in the form of a baluster. (In architecture, a baluster is a short vertical support with a circular section and a vaselike outline.)

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

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

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

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.

In glassworking, a bit of hot glass, usually small and disk-shaped, attached to the surface of an object for decorative purposes. Appliqués can be decorated by pressing them in a mold before they are attached, or they can be stamped after they are attached.

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 monochrome segment of glass cut from a trail.

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.

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.

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

(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.

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

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.

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.

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.

(from French paraison) A gather, on the end of a blowpipe, that is already partly inflated.

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

(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.

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 style of decorative art favored by the middle class in Germanic Europe between about 1815 and 1848. The name is derived from Gottlieb Biedermeier, the pseudonymous author of the satirical verses of Ludwig Eichrodt (1827-1892) and Adolf Kussmaul (1822-1902). During the period in which the Biedermeier style was popular, glassmaking revived in Bohemia, where new kinds of glass such as Lithyalin and elaborate flashed, wheel-engraved, and enameled glasses were produced for middle-class consumers.

(from Greek lithos, “stone”) A type of glass, developed in Bohemia by Friedrich Egermann (1777-1864), that is opaque and has a marbled surface resembling semiprecious stones.

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.

(1) The application of a very thin layer of glass of one color over a layer of contrasting color. This is achieved by dipping a gather of hot glass into a crucible containing hot glass of the second color. The upper layer may be too thin to be worked in relief. “Flashing” is sometimes used (erroneously) as a synonym for casing. (2) The act of reheating a parison by inserting it into a glory hole and then withdrawing it rapidly.

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.

(German, “smooth cut”) A style of engraved decoration in which the relief effect is enhanced by polishing the ground part of the intaglio. Blankschnitt decoration is frequently found on glasses engraved in the German city of Nuremberg in the 17th and 18th centuries.

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.

(from Italian, “engraving”) A method of wheel engraving whereby the ornamentation is cut into the object and lies below the surface plane. The German name for this technique is Tiefschnitt.

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

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

A tool made from a block of wood hollowed out to form a hemispherical recess. After it has been dipped in water to reduce charring and to create a “cushion” of steam, the block is used to form the gather into a sphere before it is inflated.

(from French marbre, “marble”) (Noun) A smooth, flat surface on which softened glass is rolled, when attached to a blowpipe or pontil, in order to smooth it or to consolidate applied decoration. (Verb) To roll softened glass on a marver.

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.

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 substance that lowers the melting temperature of another substance. For example, a flux is added to the batch in order to facilitate the fusing of the silica. Fluxes are also added to enamels in order to lower their fusion point to below that of the glass body to which they are to be applied. Potash and soda are fluxes.

A tool with two metal arms joined at one end by a spring. The distance between the arms is controlled by the glassworker, who uses jacks for a variety of purposes while shaping the parison (for example, to form the mouths of open vessels). This tool is also known as a borsella or pucellas.

A tool with two metal arms joined at one end by a spring. The distance between the arms is controlled by the glassworker, who uses jacks for a variety of purposes while shaping the parison (for example, to form the mouths of open vessels). This tool is also known as a borsella or pucellas.

A tool with two metal arms joined at one end by a spring. The distance between the arms is controlled by the glassworker, who uses jacks for a variety of purposes while shaping the parison (for example, to form the mouths of open vessels). This tool is also known as a borsella or pucellas.

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.

A small pitcher for serving cream.

Objects with elaborate, deeply cut patterns that usually cover the entire surface and are highly polished. In the United States, the vogue for brilliant-cut glass lasted from about 1880 to 1915.

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.

A tool used to trim excess hot glass from an object in the course of production. Many modern shears are embedded with chips of industrial diamonds.

A piece of flat sheet glass used for glazing windows.

The process of reheating a blank until it becomes soft and gradually flows under its own weight over or into a former mold and eventually assumes the shape of the mold. Soda-lime glass becomes soft at about 1110°F (600°C). Slumping is also known as sagging.

A glass cylinder intended to be cut into sheets.

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 cylindrical or truncated conical one-piece mold with a patterned interior. The mold is open at the top so that a parison can be dipped into it and then inflated. It is also known as an optic mold.

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

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.

Minute bubbles of gas, usually occurring in groups.

The pontil, or punty, is a solid metal rod that is usually tipped with a wad of hot glass, then applied to the base of a vessel to hold it during manufacture. It often leaves an irregular or ring-shaped scar on the base when removed. This is called the “pontil mark.”

Sheet glass made by blowing a parison, cutting it open, and rotating it rapidly, with repeated reheating, until the centrifugal force has caused it to become a flat disk. After annealing, the disk is cut into panes of the required shape and size. Bull’s-eye panes come from the centers of the disks and preserve the thickened area where the parison was attached to the pontil.

The pontil, or punty, is a solid metal rod that is usually tipped with a wad of hot glass, then applied to the base of a vessel to hold it during manufacture. It often leaves an irregular or ring-shaped scar on the base when removed. This is called the “pontil mark.”

(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 mixture of alcohol and turpentine, used as lamp fuel in the 19th century. Burning fluid, which was dangerously explosive, was replaced by kerosene in the late 1850s.