Glass in which the flux is boric oxide instead of alkali. The first %%borosilicate glass%% was created by Otto Schott in 1882. It has a low coefficient of expansion and therefore withstands sudden changes of temperature.

Historically, the most common form of glass. It contains three major compounds in varying proportions, but usually silica (about 60-75 percent), soda (12-18 percent), and lime (5-12 percent). Soda-lime glasses are relatively light, and upon heating, they remain plastic and workable over a wide range of temperatures. They lend themselves, therefore, to elaborate manipulative techniques.

A generic name for glass (e.g., borosilicate glass) with a relatively low coefficient of expansion. Soft glass (e.g., soda-lime glass), by contrast, has a relatively high coefficient of expansion.

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.

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.

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

A tall, thin vessel for tapers. Tapers are long wicks coated with wax for use as a spill.

A tall, narrow container for spoons. Spoon holders were used at the table from the mid-19th century to World War I.

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.

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 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 Some molds (e.g., dip molds) impart a pattern to the parison, which is then withdrawn, and blown and tooled to the desired shape and size; other molds (sometimes known as full-size molds) are used to give the object its final form, with or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 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.

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.

A craftsman who paints and/or assembles glass windows.

In glassworking, the process of coloring the surface of glass by the application of silver sulfide or silver chloride, which is then fired at a relatively low temperature. The silver imparts a yellow, brownish yellow, or ruby-colored stain, which can be painted, engraved, or etched.

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 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.

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