While there are thousands of workable formulas, glass is basically sand (silicon dioxide or silica) melted with an alkali flux such as potash and carbonates of potash or lime. To this can be added various oxides to purify or color the glass. For example, blue comes from oxides of cobalt, white from tin, purple from manganese, and green from copper or iron. And in all cases, until the standardization of this century, glass formulas were accurate only to the nearest shovelful.
Glassworks were usually located in or near forests because large amounts of fuel were needed. It proved easier to transport the raw materials to the fuel (and cart the finished glass away) than to haul wood to a more convenient site. This held true in almost all areas of Europe and America until well into the 19th century when alternate fuels, such as coal and gas, became widely used. Thus, with the exception of the island of Murano near Venice where Venetian glassmaking has been concentrated for centuries, there were rarely specific areas where glassmakers congregated. Much more common was the isolated glasshouse which moved to fresh sources when the wood ran out.
Although attempts were made as early as 1608 to make glass in America, it was not until 1739 that Caspar Wistar organized a successful glassworks in Salem County, New Jersey. It remained in business until about 1776.
Other American glasshouses sprang up where the necessities of fuel, good sand, and the proper clay for melting-pots could be brought together. From New England to Maryland and westward from Ohio to Kentucky there was glass being made. Although today's collector looks for well-proportioned tablewares, figured flasks, or glass in rare colors, it should be remembered that most of the glass made consisted of bottles and window panes.
This exhibit brings together pieces from the Museum's collection with those of two private collectors in order to show the range of late 18th to mid-19th century American glassmaking. Where possible, interesting European glasses have been added to demonstrate how similar shapes were hand led in the Old World. Pieces have been grouped by function rather than by period or place of manufacture. Unfortunately, the field is too wide to cover every type of glass, and so pressed glass is somewhat slighted while cut glass and art glass are not shown at all.
Elsewhere in the Museum there are other displays of glass. On the Main Floor, in the Ancient Galleries, there is a group of Roman glass and in the Renaissance Gallery there is some fine early Venetian glass. At the other end of this floor, at the foot of the stairs, there is an exhibit of 20th century glass.