Raw umber
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Description
A pale yellowish brown natural earth pigment that contains Manganese dioxide and iron hydroxide. See Umber.
Synonyms and Related Terms
Pigment Brown 7; CI 77492; umbra; terre d'ombre naturelle (Fr.); Umbra natur (Deut.); ombra omi (Gr.); terra d'ombra naturale (It.); ruwe omber (Ned.); grisaille; Sicilian brown
Risks
Toxic.
Physical and Chemical Properties
Slightly soluble in acids giving a yellow solution. Turns reddish brown when heated.
| Density | 3.2 g/ml |
|---|---|
| Refractive Index | 1.87-2.17 |
Additional Images
Raw umber at 500s
transmitted light
Raw umber at 500x
Polarized light
Resources and Citations
- R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966 Comment: density = 3.20 and ref. index = 1.87-2.17
- Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
- 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
- Pigments Through the Ages - http://webexhibits.org/pigments/indiv/overview/umbra.html
- Website: http://www.coloria.net/varita.htm
- Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000