Ceramic Glazing

Essay by Anonymous UserUniversity, Bachelor'sA+, December 1996

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Glazes

The knowledge of ways to form glazes on pottery is dated back to at least 5000 B.C. Since glazes were made in many parts of the world long before the beginnings of any scientific knowledge of chemistry, it is clear that the processes involved must have been simple and the raw materials were abundant. The chemical make-up of glazes was not known to the ancient people in glazing their pottery. Their results were achieved by strictly experimental methods that had no basis in scientific knowledge or theory, but their results were in no way inferior to the best of present-day glazes.

The Egyptians, who undoubtedly made the first glazed ware, used the soda compounds that are found in abundance in the desert areas of the Near East. The turquoise glazed beads, ornaments, and small sculptures, which are known as Egyptian paste, are probably the earliest glazed objects.

The glaze on Egyptian paste is formed by mixing soluble sodium salts into the clay, which, during drying deposits on the surface where it forms a glaze when fired. Such glazes may have been made accidentally at first. It is not unlikely that when objects were being molded from the desert clays and talc, some of the soda ash that is so prevalent in the desert could have been mixed in by chance. The observation of this phenomenon, and the capitalization on it in works of art and utility, is a good example of the way in which man has advanced his techniques. It was discovered that the addition of copper-bearing minerals to the mixture resulted in bright blue and turquoise glazes. The vibrant color of this type of glaze is irresistibly beautiful, yet technically there is no great difficulty in producing it from a few...