Glass, Glaze, and Enamel

If seems fhaf somefime during the third millennium b.c.e., somewhere in the Middle East, it was discovered that when a mixture of silica sand and soda is heafed to relafively high temperafures, fhe mixfure fuses to form glass. Few other human-made materials are derived, as is glass, from such common and abundant raw materials. Its remarkable physical and chemical properties made glass, already in antiquity, one of fhe most useful and ubiquitous materials in many areas of fhe world. 

molten glass is thick and cohesive it can be shaped, and, as it cools down, it hardens while keeping its shape. Solid glass is extremely tough, withstands compression better than steel, is impervious to liquids, and is resistant to chemical attack. All this makes glass useful for making utilitarian artifacts, such as containers for solids and liquids, as well as ornamental and decorative objects (Tite et al. 2002 Tait 1991). 

TABLE 26 Properties Required from Glass, Glaze, and Enamel 

Ease to work Low melting point plasticity over a wide range of temperatures Determined by properties of substrate 

Transparency Usually desirable Seldom desired since opaque layer obliterates underlying surface defects 

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The word ceramic, as here used, is intended to include glass, glazes, and enamels as well as clay products. This broader interpretation of the word is recommended by a Committee of the Amerioan Ceramic Society, Jour. Am. Cer. Soc. 3 626 (1920) and indorsed by W. A. Oldfather, ibid. 3 637 (1920). 

Strahan, D. (2001) Uranium in glass, glazes and enamels History, identification and handling, Studies Conservation 46, 181. 

Boric acid is used in the manufacture of glass (borosilicate glass), glazes and enamels, leather, paper, adhesives, and explosives. It is widely used (particularly in the USA) in detergents, and because of the ability of fused boric acid to dissolve other metal oxides it is used as a flux in brazing and welding. Because of its mild antiseptic properties it is used in the pharmaceutical Industry and as a food preservative. 

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