The Evolution Of The Composition Of Industrial Glasses: A Historical Perspective

Glass was made for centuries from sand and ashes. To decolourize glass, Venetians added manganese and extracted the alkali from the ashes with hot water. However, glass made with the extract only lacked hydrolytic resistance. In the 17th century, two ways of stabilizing clear glass were discovered: additions of lime in Bohemia; the introduction of lead in England. The exploitation of B203, first used by Schott at the end of the 19th century, led to various new glasses with low index, low expansion, high chemical resistance, low viscosity and to compositions without alkalis. The latter part of the 20th century saw two important innovations (both at Corning): flame pyrolysis to produce Si02 in bulk or as optical fibres and glass ceramics.