DORFNER Analysenzentrum und Anlagenplanungsgesellschaft mbH
Scharhof 1, 92242 Hirschau
Fon: +49 9622 82-162
E-Mail: anzaplan@dorfner.com
Glass, composition, crystal

Glass

Glass materials are usually made of silica (SiO2), lime (CaO) and soda (Na2O) derived primarily from quartz, feldspar, limestone, soda ash such as ZnO, Sb2O3, or P2O5 and, depending on glass batch chemistry requirements smaller amounts of other minerals. The soda-lime glass – the “ordinary” variety – has great commercial value for a wide range of applications as containers (bottles), flat glass (windows, mirrors, automotive), and tableware (wine glasses).

Replacing soda (Na2O) with potash (K2O) yields the sodium-potassium-lime glass (Thueringer Glas) and when all sodium is replaced the potassium-lime glass has a higher melting point. An example of this glass is the Bohemian crystal glass.Substitution of silica (SiO2) by boron and alumina oxides increases resistance against water, acids and alkaline solutions. Boron reduces the susceptibility to temperature variation and alumina the danger of crystallization. Lead crystalline glass has a very high density and is used for luxury applications like tableware or drinking glasses (wine, spirits, etc.).

A spectrum of speciality glasses incorporates a range of chemical additives to impart special properties such as in optical fibres to maximize signal transmissivity. The uviol glass, for example, contains Ba3(PO4)2 and Cr2O3 and transmits UV light down to a wavelength of 253 nm.

At Dorfner ANZAPLAN, all the tests are carried out to validate glass properties such as chemical composition, chemical resistance against acids or conformity with international regulations.