Walnut oil
Description
A natural, colorless drying oil pressed from the nuts of a Walnut tree, Juglans regia. Walnuts contain approximately 65% oil. The cold-pressed oil is pale yellow while the hot-pressed oil has a green tinge. Walnut oil dries slower and yellows less than Linseed oil, but it dries faster than Poppy seed oil. It was popular as a paint medium in Italy, the Netherlands, and Germany. Walnut oil will turn rancid and develop a strong odor on storage.
Synonyms and Related Terms
nut oil; aceite de nueces (Esp.); huile de noix (Fr.); olio di noce (It)
Risks
Turns rancid and develops a strong odor on storage.
Physical and Chemical Properties
- Liquid is soluble in ethanol, ether, chloroform, turpentine, carbon disulfide.
- Saponification number = 188-197
- Iodine number = 140-150
- Acid value = 2.5
- Density = 0.919-0.927
- Refractive Index = 1.477-1.480
| Drying oil | Linolenic acid C18:3 % ± SD |
Linoleic acid C18:2 % ± SD |
Myristic acid C14:0 % ± SD |
Palmitic acid C16:0 % ± SD |
Oleic acid C18:1 % ± SD |
Stearic acid C18:0 % ± SD |
|---|---|---|---|---|---|---|
| Linseed oil | 58 ± 1.2 | 16 ± 0.8 | – | 7 ± 1.1 | 16 ± 1.8 | 3 ± 0.1 |
| Walnut oil | 8 ± 0.3 | 72 ± 1.5 | – | 6 ± 0.6 | 12 ± 1.1 | 2 ± 0.2 |
| Poppy seed oil | 8 ± 0.7 | 70 ± 0.8 | – | 9 ± 0.5 | 10 ± 0.4 | 3 ± 0.2 |
Resources and Citations
- Tarola, A.M., A.M. Girelli, S. Lorusso, "High Performance Liquid Chromatography Determination of Fatty Acids in Drying Oils Following Lipase Action", Journal of Chromatographic Science, Vol. 50(4), April 2012, Pages 294–300.
- Mills J.. "Composition and identification of dried oil film: The gas-chromatographic examination of paint media", Studies in Conservation, 1966, vol. 11 (pg. 92-106) Part I. Fatty acid.
- M.Serpico, R.White, "Oil, fat and wax" in Ancient Egyptian Materials and Technology, P.Nicholson, I.Shaw (eds.), Cambridge University Press, 2000, p. 390-429.
- Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971
- 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)
- Reed Kay, The Painter's Guide To Studio Methods and Materials, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1983
- 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