Glass coloring, selenium

Stained glass colors. Addition of a selenium compound produces red glass, and an addition of a cobalt compound produces blue glass. 

Of the important properties of glass, color is one of the most interesting. Color is usually achieved by the addition of various metal oxides. The strongest of these are titanium, vanadium, chromium, manganese, selenium, iron, cobalt, nickel and copper. Silver and uranium will give weak colors. Some of the rare earths are also used as colorants with sharp absorption bands in contrast to the broad bands given by most colorants. (4)... 

Selenium is used in a wide variety of industries, including electronics, glass, ceramics, glass coloring, steel, pigment manufacturing, and rubber production. Medicinally, selenium is used in antidandruff shampoos and as a dietary supplement. 

Selenium is used in Xerography for reproducing and copying documents, letters, etc. It is used by the glass industry to decolorize glass and to make ruby-colored glasses and enamels. It is also used as a photographic toner, and as an additive to stainless steel. 

The color obtained is a function of both the composition and the particle size of the precipitated crystals. A redder color results from both increased selenium to sulfur ratio and from larger crystals, caused by a more severe heat treatment. Hence, it is possible to make, from the same glass, a series of color filter types, by controlled reheating. 

Domestic consumption of selenium in 1981 exceeded 453,000 kg. About 50% was used in electronic and copier components, 22% in glass manufacturing, 20% in chemicals and pigments, and 8% miscellaneous (Cleveland et al. 1993). In 1987, world production of selenium was about 1.4 million kg (USPHS 1996). In 1986, 46% of the global selenium produced was used in the semiconductor and photoelectric industries 27% in the glass industry to counter coloration impurities from iron 14% in pigments and 13% in medicine, in antidandruff shampoos, as catalysts in... 

Colored bodies, 7 342-343 Colored glass, selenium uses in, 22 96-97 Colored images, steps in the formation of, 19 234-235... 

Beryllium connections and contacts are employed for switchgear and relays. Beryllium oxide is used as substrata for electronic circuits. Cadmium is used in television and fluorescent light phosphors. Cadmium, nickel and mercury are employed in batteries such as "nicad" cells and mercury cells. Mercury is used in fluorescent lamps, electrical switches, and outdoor lamps, as well as instruments for measuring pressure, temperature, and density. Selenium is employed as a photoreceptor in copying machines, and as a semiconductor in rectifiers. Lead applications include lead add storage batteries, a component in color television glass, and, in its oxide form, use as a dielectric material. 

Commercial uses of Se, Te, and Po are limited, though selenium is used to make red colored glass and in photocopiers (see the Interlude at the end of this chapter). Tellurium is used in alloys to improve their machinability, and polonium (2i0po) has been used as a heat source in space equipment and as a source of alpha particles in scientific research. 

Selenium is also used to impart a ruby-red color to glass, and to neutralize the green color in glass which is due to the presence of iron. 

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