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The dark, brownish-black bituminous resins occur naturally and are produced as byproducts of oil refineries. Ancient sources for asphalt include Egypt, the north end of the Dead Sea, the Is river northwest of Babylon, and the Greek island of Zante. Gilsonite is the hardest, most brittle variety. Some softer, more elastic varieties are Trinidad, Barbados, California, and Egyptian asphalts. They were often collected from pits or lakes and thus were sometimes called lake asphalts. Asphalts are soluble in oils and waxes and can act as a plasticizer or a strengthener depending on the hardness of the variety. They are composed of aliphatic, alicyclic and polycyclic aromatic hydrocarbons. Asphalts, under the name of Asphaltum and Bitumen, were also used as pigments to form a transparent brown film. Unfortunately, thick films with asphaltum often exhibit crawling, alligatoring, and disfigurement. In addition, asphalt was sometimes mixed with dry Clay or Limestone for use as an adhesive. Asphalt is used commercially for road paving, roof coating and joint sealing. It is also used as a waterproof barrier in sandy soils.

Synonyms and Related Terms

asphaltum; bitumen; Asphalt (Deut.); asfalto (Esp., Port.); asphalte (Fr.); asfalt (Ned., Pol., Sven.); asfalto (It); bitume (It); gilsonite; trinidad; barbados; bentonite; gum asphaltum; coal; coal-tar; anthracite; earth pitch; Trinidad pitch; mineral pitch; lake asphalt


Combustible. Inhalation of fumes is toxic.

Physical and Chemical Properties

Soluble in carbon disulfide, toluene, chloroform, ether, acetone, turpentine, naptha. Insoluble in water, ethanol, acids and alkalis.

Burns with a bright flame.

CAS 8025-42-4
Density 1.0 - 1.2 g/ml
Refractive Index 1.635

Resources and Citations

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  • 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
  • Richard C. Wolbers, Nanette T. Sterman, Chris Stavroudis, Notes for Workshop on New Methods in the Cleaning of Paintings, J.Paul Getty Trust, Los Angeles, 1990
  • Henry Hodges, Artifacts: An Introduction to Early Materials and Technology, Ronald P. Frye, Kingston, Canada, 1988
  • The Dictionary of Paper, American Paper Institute, New York, Fourth Edition, 1980
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 880
  • 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
  • CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: density=1.1-1.5; ref. index=1.635