All About Glass
All About Glass
This is your resource for exploring various topics in glass: delve deeper with this collection of articles, multimedia, and virtual books all about glass. Content is frequently added to the area, so check back for new items. If you have a topic you'd like to see covered, send us your suggestion. If you have a specific question, Ask a Librarian at our Rakow Research Library.
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.
(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. Lithyalin Beaker
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.
Composite arrangements of pieces of flat glass that are held together by lead (or sometimes by zinc or some other metal) cames. Stained glass windows are the most prominent examples of leaded glass. Panel with Washington Coat-of-Arms Panel with Washington Coat-of-Arms
Glass that contains a high percentage of lead oxide (at least 20 percent of the batch). In modern times, glass of this type was patented in 1674 by George Ravenscroft (1632-1683), who added a larger amount of lead in 1676. Lead glass is relatively soft, and its refractive index gives a brilliance
(from Greek, “small mixing bowl”) A small vessel with a wide mouth and body, and a foot. The term is often used to describe certain core-formed Egyptian vessels of the second millennium B.C.
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. Beaker
(from Italian intarsio, “marquetry”) A type of glass developed by Frederick Carder (1863-1963) about 1920. A design of colored glass was applied to a parison of a different color, then flashed with a second parison of the same color as the first. Intarsia Footed Vase
(Italian) The technique of constructing an object, usually a vessel, by fusing two or more blown glass elements. The process, first practiced in the Islamic world in the Middle Ages, demands great precision because the edges of the adjoining elements must have precisely the same diameter. Giada
A highly corrosive acid that attacks silicates such as glass. Pure hydrofluoric acid dissolves glass, leaving a brilliant, acid-polished surface.
The process of breaking away the edge of a glass object with a grozing iron or pliers in order to shape it.
A type of decorative glass developed by Orrefors of Sweden in 1916. The design is carved, engraved, or etched on a parison of colored glass, which is then reheated and cased in a thick layer of transparent glass of a different color, and inflated.
Decoration that consists of narrow vertical grooves (flutes). Fluted Vase
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. Pitcher
Clay capable of being subjected to a high temperature without fusing, and therefore used for making crucibles in which glass batches are melted. Fire clay is rich silica, but it contains only small amounts of lime, iron, and alkali.
The process of completing the forming or decoration of an object. Finishing can take the form of manipulating the object into its final shape while it is hot, of cracking off before annealing, or of cutting, enameling, grinding, or polishing.
A fired silica body containing small amounts of alkali, and varying greatly in hardness depending on the degree of sintering. It is covered with glaze, which may also be present interstitially among the quartz grains within the body. The term “glassy faience” is often used to describe a faience in
(French, “manner, or style, of Venice”) Glass made in imitation of Venetian products, at centers other than Venice itself. Façon de Venise glass was popular in many parts of Europe in the 16th and 17th centuries. Winged Goblet
A synthetic material, copper calcium tetrasilicate, with a distinctive blue color. In antiquity, Egyptian blue was made by heating together silica, lime, and a copper-containing ingredient. It is often confused with faience and misleadingly called frit.
(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. Royal
(1) The process whereby glass becomes partly crystallized as it cools (usually too slowly) from the molten state; (2) the crystals formed by this process. Devitrification can also occur on the surface as a result of unsuccessful annealing or accidental heating to a high temperature. It is not
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. Cordial Glass
(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. Goblet
A part of the glass that differs in composition from the surrounding matrix. This difference produces a change in the refractive index, which enables the cord to be seen as a streak and so spoils the appearance of the glass.
A type of decorative glass developed by Frederick Carder (1863-1963) at Steuben Glass Works in Corning, New York, before 1917. Most Cintra glass was made by picking up chips of colored glass on the parison and then casing them with a thin layer of (usually) colorless glass. Cintra Vase
A thin, monochrome rod, or a composite rod consisting of groups of rods of different colors, which are bundled together and fused to form a polychrome design that is visible when seen in cross section. Bar Rod Mosaic glass
A grooved strip of lead or (rarely) another metal, generally with an H-shaped cross section, used to join separate parts of glass windows. St. Matthew
(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. Ewer
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. Vase in "Rookwood" Pattern
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.