Asphaltum

Mexican effigy
1993.775

Description

1) An old name for Asphalt generally used prior to the 1800s.

2) In the 17th and 18th centuries, the term asphaltum also referred to a transparent brown, Asphalt-based pigment used in watercolor and [[oil paint|oil paints] for glazes and shadows. The oily material can slow the drying of Linseed oil producing a soft film. With time, asphaltum in dried oil films can result in the movement or disfigurement of the film as well as alligator cracks. Asphaltum was sold commercially as a transparent brown artist pigment under the name bitumen (Gettens and Stout 1966).

Synonyms and Related Terms

2) bitumen; Antwerp brown; asphalt paint; Asphalt (Deut.); asfalto (Port.); asphalte (Fr.); asfalto (Esp.); asfaltos (Gr.); alfalto (It.); bitume (It.); asfalt (Ned.); asfalto (Port.)

FTIR

Risks

Combustible. Softens at slightly elevated temperatures.

Ages poorly in dried oil films resulting in movement, disfigurement and/or cracks.

Physical and Chemical Properties

Soluble in petroleum hydrocarbons, turpentine, and most organic solvents. Partially soluble in oils.

Microscopic ID: amorphous, brown particles with conchoidal fracture and/or curved particle boundaries. RI < 1.662. Isotropic in crossed polars.

Additional Images

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  Asphaltum, PPL, 200x

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  Asphaltum, XPL, 200x

Resources and Citations

• R.White "Brown and Black Organic Glazes, Pigments and Paints" National Gallery Technical Bulletin, 10:58-71, 1986. ° R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966

• 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)

• 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

• R.D. Harley, Artists' Pigments c. 1600-1835, Butterworth Scientific, London, 1982

• Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996

• Thomas B. Brill, Light Its Interaction with Art and Antiquities, Plenum Press, New York City, 1980

• Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000

• Eastaugh, N. et al. The Pigment Compendium, a Dictionary and Optical Microscopy of Historical Pigments, Butterworth-Heinemann, 2008.