Corning Museum of Glass

A decorative technique in which gold or silver leaf is applied to the back side of a piece of glass, engraved, and protected by varnish, metal foil, or another piece of glass.

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 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.

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 which the reactions have proceeded to such an extent that the glass phase defines the visual appearance of the material.

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

Batch ingredients such as sand and alkali, which have been partly reacted by heating but not completely melted. After cooling, frit is ground to a powder and melted. Fritting (or sintering) is the process of making frit.

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.

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.

A low-temperature kiln for refiring glass to fuse enamel, fix gilding, and produce luster.

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.

A fire-clay box in which glass (or porcelain) objects are enclosed, when placed in the muffle kiln, to protect them from the flames and smoke while they are subjected to low-temperature firing, especially in the process of firing enamels and gilding at temperatures of about 950°-1300°F (500°-700°C).

The process of (1) heating the batch in order to fuse it into glass by exposing it to the required temperature in a crucible or pot, (2) reheating unfinished glassware while it is being worked, or (3) reheating glassware in a muffle to fuse enamel or gilding. The melting of the batch may require a temperature of about 2400°-2750°F (1300°-1500°C), whereas the muffle kiln may require a temperature of only about 950°- 1300°F (500°-700°C).

An oven used to process a substance by burning, drying, or heating. In contemporary glassworking, kilns are used to fuse enamel and for kiln-forming processes such as slumping.

(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 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 small ornamental object of white porcelainlike material, made to be encased in glass. The term is also applied to objects that are decorated with sulphides. They were popular in Europe and America throughout the 19th century. The term “sulphide” is probably connected with the use of sulfur by 18th- and 19th-century moldmakers.

The English term for an object made by a glassworker on his own time. Most friggers were made from the molten glass that remained in the pot at the end of the day. Such glass was considered to be a worker’s perquisite. American glassworkers referred to friggers as “end-of-day” objects. They are also known as whimsies.

The English term for an object made by a glassworker on his own time. Most friggers were made from the molten glass that remained in the pot at the end of the day. Such glass was considered to be a worker’s perquisite. American glassworkers referred to friggers as “end-of-day” objects. They are also known as whimsies.

The English term for an object made by a glassworker on his own time. Most friggers were made from the molten glass that remained in the pot at the end of the day. Such glass was considered to be a worker’s perquisite. American glassworkers referred to friggers as “end-of-day” objects. They are also known as whimsies.

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

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.

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.