Mastic resin
Description
A pale, yellow natural resin produced by the evergreen mastic shrub, Pistacia lentiscus, which occurs in southern Europe and northern Africa. Mastic is a triterpenoid resin; some of its identified components are euphane, oleanic acid and a bicyclic diol (Mills and White 1994). Mastic is sold commercially in small, transparent 'tears' of a pale straw color. The resin collected from the Greek island of Chios has a reputation for the highest quality. Mastic was used in 16th and 17th century recipes for oil/resin varnishes and later in with mixtures of other resin. In the 19th century, mastic was a popular clear, glossy spirit varnish for oil paintings and was also used as an additive in oil medium called megilp. By the 20th century, its use as a varnish was superseded by dammar. Mastic varnish is prepared by placing the resin bits in a gauze bag suspended in solvent. Mastic varnishes yellow and become insoluble with age. Mastic is also used as a chewing gum and a flavoring agent in an alcoholic beverages and ice cream (called mastica).
Note: The word 'mastic' has also been used to refer to a black adhesive. For furniture and musical instruments, black mastic was used for pearl and ivory inlays. Resinous mastic, however, did not adhere well because it shrank, and thus, was soon replaced with Hide glue mixed with Ebony dust, but the name 'black mastic' was retained. In the 20th century, the name 'black mastic' was used for flooring adhesives made with Bitumen or Asphalt. Prior to 1984, the adhesives may have contained Asbestos.
Synonyms and Related Terms
Pistacia lentiscus; Mastix (Deut.); resina almáciga (Esp.); lentisque (Fr.); pistachier lentisque (Fr.); resina mastice (It); mastiekboom (Ned.); mastix (Sven., Slov.); mastich; mastica; gum mastic; Chios mastic; Indian mastic; Bombay mastic; khinjak; Turkish mastic; pistacia galls; lentisk, meglip
Applications
- Coatings (oil/resin varnish, spirit varnish)
Risks
- Darkens with age.
- May turn cloudy if moisture is present during preparation.
- Black mastics used for flooring in the 20th century may contain asbestos along with bitumen or asphalt.
Physical and Chemical Properties
- Soluble in oil, turpentine, ethanol, diethyl ether, benzene, acetone, chloroform. Insoluble in water and ligroin.
- Saponification number = 82-92.
- Acid number = 50-71.
| Melting Point | 95-120 C |
|---|---|
| Density | 1.074 g/ml |
| Molecular Weight | Tg =34.7 C |
| Refractive Index | 1.535-1.536 |
Comparisons
Additional Images
Mastic Resin on glass at 100x (visible light left; UV light right)
Mastic Resin on primed canvas at 100x (visible light left; UV light right)
Mastic shrub (Pistacia lentisicus)
radial section at 100x
Mastic shrub (Pistacia lentisicus)
tangential section at 100x
Mastic shrub (Pistacia lentisicus)
transverse section at 100x
Resources and Citations
- E.Mention, "Natural Resin Varnishes: Mastic" AIC Painting Conservation Catalog, Varnishes and Surface Coatings, p.55, 1998.
- J.S. Mills, R.White, The Organic Chemistry of Museum Objects, Butterworth Heinemann, London, 1994.
- Encyclopedia Britannica, http://www.britannica.com Comment: "Mastic." (Accessed 14 Apr. 2004).
- Wikipedia: http://en.wikipedia.org/wiki/Mastic (Accessed Feb. 10, 2006)
- R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966 Comment: melting point = 95C; specific gravity = 1.074
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 500
- Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
- Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986 Comment: meltin point=105-120 C
- Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
- Thomas B. Brill, Light Its Interaction with Art and Antiquities, Plenum Press, New York City, 1980 Comment: ref. index = 1.536
- 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
- Paintings Specialty Group, Painting Conservation Catalog, Wendy Samet (ed.), AIC, Washington, DC, 1998
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
- Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
- CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: Brill - ref. index = 1.535