Glass

Common glass is mostly amorphous silicon dioxode (SiO₂), which is the same material as sand? and quartz. Most common glass has other ingredients added to change the properties. Leaded glass is more brillant, while boron may be added to change the thermal and electrical properties. Adding barium will increase the refractive index, and cerium is used in glass that adsorbs infrared energy. Other metal oxides are added to change the color. Soda? or potash? are sometimes added to lower the melting point, and manganese can be added to remove other colors.

History of Glass

While naturally occuring rock crystal (a clear form of quartz) has been used since before written records were kept, the first documented glass making is in Egypt around 2000 B.C., where sheets of glass were created by the melting of sand on molten lead, which is now called "float glass" as the glass floats to the surface. During the Roman Empire many forms of glass were created, but until the 1100's [stained glass]? (which is glass with some metals added for color) glass was not widely used. Venetian? glass was highly prized between the tenth and fourteenth centuries as they kept the process secret. Around 1688, the process for casting glass was developed, which led to it being a much more commonly used material. The invention of the glass pressing machine in 1827 allowed the mass production of inexpensive glass articles.

Fine glassware

Even with the availablity of comman glassware, there remains place for hand blown glassware. Some artists in glass include [Sidney Waugh]?, [René Lalique]?, and [Louis Tiffany]?, who were responsible for extraordinary glass objects. The term "crystal glass", derived from rock crystal, has come to denote high-grade colorless glass and is sometimes applied to any fine hand-blown glass.