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Ostrich egg ewer
MFA# 63.1257


A term whose primary meaning in art, refers to the ellipsoidal shell and embryonic contents produced by birds. For paintings, the egg contents are used as a tempera medium. The whole egg, yolk, or white may be used sometimes mixed with oil and/or resin. The Egg yolk is a stable emulsion of an aqueous liquid with an oily, proteinaceous medium which dries quickly into a hard, insoluble film. Egg white, or glair, has been used as a medium for illuminated manuscripts. It is also used as a size for attaching Gold leaf. Albumen is the adhesive substance of egg white. As a pure film, albumen is clear, brittle, and water soluble. Water solubility can be decreased by heating or adding Tannin. The exterior of a bird egg is covered with a brittle shell composed of Keratin and Calcite.

FTIR egg with kaolin (MFA)

Egg (Gettens 52-18) with kaolin.TIF

Synonyms and Related Terms

Ei (Deut.); huevo (Esp.); œuf (Fr.); uovo (It.); ei (Ned.); jajo (Po.); ovo (Port.); ägg (Sven.)

Physical and Chemical Properties

Miscible with water when fresh. Insoluble in water after heating.

Resources and Citations

  • R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
  • Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
  • John S. Mills, Raymond White, The Organic Chemistry of Museum Objects, Butterworth Heineman, London, 2nd ed., 1994
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998