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A material added to a ceramic glaze or enamels to increase its optical density, i.e., make it more opaque. Opacifiers can also make the glaze shinier, more homogeneous and less likely to craze. Tin oxide is one of the best opacifiers for ceramics and it also acts as a flux. Zirconium oxide is also used as a less expensive alternative. Titanium dioxide adds hardness and chemical resistance to the enamels. Some pigments, such as Cobalt oxide (blue), Platinum dioxide (gray), and Lead chromate (red/green) also act as opacifiers.

Synonyms and Related Terms

opacifiant (Fr.); opacizzante (It.); glansmiddel (Ned.); opacificante (Port.); Lufax [Rohm & Haas]; Zircopax [Titanium Alloy Mfg.]; Opax [Titanium Alloy Mfg.]; Superpax [Titanium Alloy Mfg.]; Ultrox [M&T Chemicals]

Resources and Citations

  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 562
  • Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998