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Glass (G) - Encylopedia Of Antiques

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GERMAN GLASS: Early German glass was much influenced by Venetian methods and shapes. During the 16th century, however, the characteristic enameled glass was made in distinctively national shapes and continued to be made during the 17th and 18th centuries. The best known and most popular are the large cylindrical beakers of white or green glass, enameled with the coat-of-arms of the owner or the arms of the different states. These beakers have been copied by the glassmakers of later periods.

GIMMAL FLASK: A flask or bottle, containing two separate compartments, each with a spout. Used as a container for oil or vinegar, usually.

GLASS: The invention of glass dates from the earliest antiquity and may probably be attributed to the Egyptians. Glass, at first, was doubtless opaque, then translucent and finally transparent. These various steps meant long centuries of experiments. In Rome, the art of glassmaking was developed to a high pitch of excellence, and it is said that glass was employed there for a greater number of purposes than it is today. Colored and ornamental glass held much the same place then that china does among us today. It was also used in slab form for wall decoration, colored in imitation of veneers of marble or porphyry. In Europe, for nearly a thousand years little glass of artistic interest was produced, excepting the stained glass (q.v. ) used in the windows of the Gothic churches. Glass-making flourished in Constantinople throughout the Dark Ages, and Venice, where glass-making became a monopoly in the 13th century, received its impulse from Constantinople. From Venice glass-making made its way gradually to France and to England, until in the 16th and 17th centuries it was established in those countries and in other parts of Europe, notably Bohemia.

The history of modern glass begins with the Venetian crystal glass of the 16th century, the first since the time of the Romans. The base of all glass is sand or silica, and the alkalies used are principally soda, lime, and potash. Lead is sometimes used to replace the alkalies, in whole or in part. Glass is formed by the fusion of the mixture to form silicates in various proportions, according to the qualities required. Glass has certain peculiar properties: in ductility, when heated, it ranks next to gold; it is flexible and elastic when heated but extremely brittle when cold; it can be drawn into a thread sufficiently fine to be woven into a fabric, and to such a degree of thinness that it may remain suspended momentarily in the air; it resists the action of all acids excepting hydrofluoric acid.

The composition of the principal kinds of glass is: Window and plate glass; silica, soda and lime.The so-called crown glass is the best of the window glass.Flint and crystal glass; silica, potash and lead. The greater ease with which flint glass could be fashioned led to its adoption for tableware, decanters and the better grades of bottles. Bottle glass; silica, lime and alumina. Bottle glass is the cheapest of all glass.

Any of the above kinds of glass may be colored by the use of metallic oxides. See Colored Glass.

Agate Glass. Also called slag glass. It is the glass made from iron slag, which is very fusible, cryolite and manganese, producing a variety of curious color combinations. Glass of this description was made, especially at one period, from 1900 to 1903, in chocolate and golden agate color. See AGATA GLASS.

Blown Glass. The methods of glass blowing and the tools with which it is done are now very little different from those which have served workers in glass from the remotest times. The blowingtube was in use by the Romans at the beginning of the Christian Era, and specimens of blown glass of that period are numerous. Blown glass was also made in Spain, in Gaul and in Southern England during the Roman occupation. Until glass blowing by machine was perfected, blown glass was just what its name implies; blown by the air from the lungs of the glass-worker. All glass was blown glass up to the time of the invention of a method of pressing glass in molds by an American mechanic about 1827, which process, by reducing cost of glass manufacture, revolutionized glass-making in this country and abroad. Blown glass, however, is more lustrous and more desirable from the collector's viewpoint than pressed glass. See Three-Mold Glass.

Cameo Glass. Glass, usually colored, with a partial or complete coating of opaque white glass, upon which the relief ornament was carved. It was known to the skilled glass-makers about the time of the Christian Era, and the Portland Vase (q.v.) is a survival of that period. Glass of that description was not again made successfully until the last half of the. 19th century, by Thomas Webb & Sons at Stourbridge, England.

Colored Glass. Colored glass was a feature of both early Venetian and Bohemian glass. It was also made by the Romans, both opaque and transparent, in a variety of colors with the exception of ruby red, which appears to have been unknown to them. The earliest made in England was at Stourbridge about 1750. Excellent colored glass was also made later at Bristol, London, and other places in England and in this country. Stiegel colored glass was at once one of the earliest and one of the most beautiful. The industry was well established before the end of the century both here and abroad, and a great variety of table ware and toilet articles were made of colored glass. The formulas for making this glass include the following oxides in addition to that for flint glass: Blue transparent glass:-oxide of cobalt Red ruby:-oxide of gold Amethyst or purple:-oxide of manganese Emerald green:-copper scales and iron ore Orange:-iron and manganese Gold topaz:-oxide of uranium Hard white opaque:-putty prepared from tin and lead Soft white opaque: arsenic and antimony See Stained Glass.

Crackled Glass. This kind of glass is said to have been first made in the 16th century by the Venetians, and the effect probably was obtained by suddenly cooling the surface when the object was half blown.

Crown Glass. A superior quality of window glass made without lead.

Cut Glass. All cut glass is, of course, easily distinguishable. It is usually of thick-walled vessels of flint glass, sharp to the touch and heavy. The cutting is produced by pressing the glass against grinding wheels, and the ground parts are finally polished on a wooden wheel supplied with a fine polishing material. Cutting on glass originated probably in Bohemia in the 17th century. It does not seem to have spread into other European c,ountries until about the second decade of the 18th century. In England, it was first mentioned about 1720, and it was not made in Ireland until after about 1740. In this country it was not generally made until during the second quarter of the 19th century. The fine early English, Irish and American cut glass was always from blown glass, not pressed. See LIBBEY GLASS COMPANY.

Enameled Glass. The enameled glass of the Saracens during the 13th, 14th and 15th centuries was the most decorative and magnificent of all glass ever made. It was, furthermore, the first application of solid enamels to the surface of glass, porcelain or faience. It probably had its origin in the enamels used on metals of the Byzantine Era. On the opaque white glass made at Bristol, England, in the second half of the 18th century, enameled colors were applied in a most artistic fashion and then fired.

Engraved Glass. Engraved patterns are produced by applying emery powder, mixed with oil, to the edges of small revolving copper discs. Engraving by the use of a diamond preceded the use of the wheel. Some of the best engraved glass produced here was made by the New England Glass Co. at Cambridge.

Etched Glass. By the use of hydrofluoric acid an exquisite form of decoration is obtained, seeming hardly more than a shadow of a design blown upon the glass. The glass is first coated with wax and the design is then scratched upon it.

Oddly, according to chemical history hydrofluoric acid was not discovered until 1771, by Scheele, although Henry Schwanhardt of Bohemia first etched glass about 1670, by what he called "aqua fortis." It is probable that there was a considerable amount of fluorspar in the glass and that, through the reactions in his process, Schwanhardt may unwittingly have been the real discoverer of hydrofluoric acid.

Flint Glass (or Crystal Glass). This glass, essentially a silicate of lead and potassium or sodium, was developed, it is claimed, in England. in the last half of the 17th century. A certain amount of the earlier glass was actually made with flints, from which it derives its name, but by the end of the 17th century, lead glass displaced the flint. The materials used are carefully selected as the glass must be of great purity. It is heavy and, in the best quality, of great brilliance and lustre. It cuts and polishes as finely as rock crystal. England claims to have been the first country to have perfected the glass as we now know it.

Lime Glass. A substitute for lead flint glass discovered in 1864 by William Leighton, a chemist employed in a glass factory at Wheeling, West Virginia, which enabled glass manufacturers to produce a glass for tableware and other purposes at a greatly reduced cost. This discovery had a very Injurious effect upon some of the leading glass-works, notably those of New England, before they could adapt themselves to this new competition. Lime glass cools and is finished more quickly than lead glass.

Milk Glass. An opaque, white and translucent glass resembling porcelain. This glass, for which Bristol glass (q.v. ) is famous, was known to the Egyptians and it was in use by the Romans. Its revival is credited to the Venetians, and it was made at various glass factories in the Low Countries, Germany, Bohemia, France, and Spain, besides England. All decorated it after the manner of porcelain with gilding and enamel colors. None of it, however, is quite equal to that of Bristol, and genuine old Bristol glass of that kind is exceedingly rare. Much of the glass that collectors and dealers call Bristol is German or Dutch.

Mirror Glass. This glass was at first made only at Venice, but mirrors backed by lead or tin were produced in the 13th century, and in the last half of the 17th century mirror glass was made in France and in England. A Frenchman rediscovered a way about 1688 to make large mirrors from -flat, cast plates of glass, and his product is to be seen in the Palace at Versailles. This result was obtained by casting and by subsequent rolling and polishing the plates, after which they were coated with a tinmercury amalgam. The same method was introduced into England about a hundred years later. Specimens of the early English mirrors are to be found in many places in England, notably at Hampton Court Palace. Most of this early English glass was made at Vauxhall (q.v.), from blown glass in cylinder form, split open, flattened and polished; the backs being silvered by mercury floated over tin foil.

Molded Glass. Glass was blown in molds before the time of the Christian Era and the process has been continued to modern times. In the blowing in the full-size mold, the air forced the plastic glass into the form of the design cut in intaglio on the inside surface so that the finished piece, when taken from the mold, showed a depression on the inside to correspond to each protuberance on the outside. This glass, known to collectors as "three-mold glass" (q.v.), is much sought for. The patterns used in this country are roughly in three forms: geometric, arched and Baroque, and constitute one means of differentiating this type from other types of glass. The patterns of old English and Irish glass are simpler. Similar molds are used for pressed glass (q.v.) but the patterns, as a rule, are more intricate than those designed for blown glass. The mold marks are more prominent, the inside of the glass is smooth, and the glass lacks the lustre of the blown glass.

Off-Hand Glass. This name was given to that work of the early American glassmakers done in their spare moments, designed for their own use or for gifts to friends. Both useful and ornamental articles were made from the left-over ends of batches, and examples of this glass are eagerly sought by collectors.

Opal Glass. See White Glass.

Opalescent Glass. See White Glass.

Overlay Glass. See GLASS OVERLAY.

Pattern Glass. Name given to the pressed glass produced by all American factories in large quantities from about 1840 onwards. Until about the time of the Civil War this was all lead flint glass, after which lime glass, being cheaper, was substituted. This last does not have the bell-like ring of the flint glass. The number of the patterns used and their variations are almost without end. One writer asserts that there are nearly three hundred patterns that are collectible in sets. The low price of this glass, compared with blown glass, and the demand for it gave the manufacturers opportunity for quantity production and they took advantage of it. See PATTERNS IN GLASS.

Pressed Glass. Pressed glass is so-called because the glass is pressed into the mold by means of a plunger with a long handle or lever, instead of being blown into it. By this method, the piece is smooth on the inside, regardless of how deep the design or pattern may be on the outside surface. The molds are similar in construction to those for blown glass, although the patterns differ in style and variety of design. It is a less expensive and quicker process of making glass.

Experiments in pressing glass begar, about the same time (1827) at both Cambridge and Sandwich, Massachusetts, and the method, once firmly established, revolutionized glass-making everywhere. In 1836, it was being, made at Birmingham, England, and irt France, Germany and Austria at about the same time. This caused a bad break in the prices of glass abroad, but in this country it seemed to put the glass industry on its feet. By the middle of the 19th century it had invaded every market here and abroad and three-fourths of the product of American glass-works was pressed glass. Pressed glass is considered less desirable from the collector's standpoint, as it lacks the lustre of blown glass, for as a rule the glass is not of as good metal. See Pattern Glass.

Silvered Glass. This type of glass was made by blowing a thin glass object and coating this with a silvery substance, after which another thin layer of glass was "cupped" over the silver surface. Another method was to pour the silvery substance into the space between the glass layers through a hole where the pontil was located, and the hole afterwards was plugged. This plug or seal must be kept closed, for if the air is allowed to enter, the silver coating gradually disappears. This kind of glass was made by the New England Glass Company at Cambridge as early as 1850.

Stained Glass. The stained glass, which in the later Middle Ages was restricted to use in the windows of the churches, is actually colored and painted glass. It had a high potash content, which served to promote the brilliancy of the colors. The most ancient stained glass window in existence today is in the Abbey of St. Denis near Paris, dedicated in 1142. The most beautiful, perhaps, are those of the Church of St. Chapelle in Paris, and in the Cathedral of Chartres, where there are 146 windows of stained glass, depicting about five thousand human figures. Stained -glass for windows was also made in England in the 15th century and probably even earlier. See Colored Glass.

Three-Mold Glass. The abbreviation of the term, blown contact, three-section mold. (See also Insufflated). Only the earlier glass which was blown, not pressed, into a mold is properly called "three-mold" glass. It is blown in fullsize three-piece contact molds or in a small open-top mold. In the open-top mold, the glass is reheated and expanded by blowing and shaping in the open, leaving a suggestion on the surface of the pattern of the mold. This type of glass is a product peculiar to America of the early 19th century. The patterns used for this glass are a distinctive feature, and are quite different from those for pressed glass. They are, however, more elaborate than those used in making English and Irish blown glass. Nearly all of the so-called three-mold glass was made before 1850. A large proportion of this glass was made at Sandwich and at the New England Glass Co. in Cambridge. The pressed "pattern" glass is chiefly of a date later than 1850. See Molded Glass.

White Glass. Opaque white glass (called opal) owes its opacity to oxide of tin added to the regular glass formula. See Milk Glass.


GLASS OVERLAY: This effect was obtained by blowing the desired object and one or two corresponding "cups" to fit over the first piece. After cooling the design was obtained by cutting through the outer layer or layers to the under surface.

GLASSBORO (New Jersey) GLASS WORKS: This factory was started about 1780 by Stanger Bros. About 1840, Whitney Bros. purchased the plant, since known as the Whitney Glass Works. Bottles and flasks were their principal product. In 1850, they produced the "Jenny Lind" flask, with globular bottle and long slender neck, with a relief portrait on the side, which was very popular. This is one of the two oldest glassworks in the country to have had a continuous existence, the other being the Dyottville Glass Works (q.v.) at Kensington, Pennsylvania. The Glassboro plant is now a part of the property of the Owens Bottle Company.

GREENSBORO (Pennsylvania) GLASS WORKS: This was a glass factory, established by Christian Kramer and other Germans about 1807, who had earlier come to this country with Amelung (q.v.) and after the failure of that enterprise had drifted west. Here were produced some of the choicest pieces of our early glassware in amber, green, cobalt and other colors and in various attractive designs. This glass is also referred to as "Kramer family" glass. The factory continued in operation until 1849.