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An aqueous solution of calcium hydroxide produced by slaking lime. Limewater, is a colorless somewhat milky solution that is strongly alkaline even though calcium hydroxide is only slightly soluble in water. Limewater was used to saturate plaster before the application of secco colors. It is also used in calamine solutions and as an antacid.

Synonyms and Related Terms

calcium hydroxide; milk of lime; lime water

Chemical structure


Other Properties

A saturated solution of calcium hydroxide has a pH of 12.4.

Composition Ca(OH)2
CAS 1305-62-0
Melting Point 580 (dec)
Molecular Weight mol. wt. = 74.1

Hazards and Safety

International Chemical Safety Card

Sources Checked for Data in Record

  • Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942
  • Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
  • Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
  • External source or communication Comment: Eric Hansen, contributed information (April 2001)
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985