An exudate from several species of shrubs of the genus Astragalus (especially Astragalus gummifer) found in the dry regions of Iran, Iraq, Syria, and Turkey. Gum tragacanth consists of a complex mixture of acidic polysaccharides containing galacturonic acid, Galactose, fucose, Xylose, and Arabinose. Tragacanth gum is available in the form of dull white, translucent plates (fiori) or as a yellowish powder (biondo). A soluble fraction, tragacanthin, dissolves when added to water, whereas an insoluble fraction, bassorin (60-70% by wt.) swells to a gel-like state. A solution of gum tragacanth is prepared by wetting the powder with alcohol, then adding water and shaking. Aqueous solutions are slightly acidic with a pH of 5-6. Gum tragacanth is used for textile sizing and printing, pastel crayon production, leather curing, and furniture polishes.
Synonyms and Related Terms
goma de tragacanto (Esp.); gomma adragante (It); gomma tragacante (It); olibanum; tragacanth; gum dragon; gomme adragante; Smyrna tragacanth; Anatolian tragacanth; Persian tragacanth; gum elect; fiori; biondo
- Inhalation and skin contact may cause allergies.
- Fisher Scientific: MSDS
Physical and Chemical Properties
Water swellable after wetting with ethanol. Soluble in alkali and hydrogen peroxide. Insoluble in ethanol.
Resources and Citations
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- The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 4609
- Encyclopedia Britannica, http://www.britannica.com Comment: "gum." Accessed 7 Apr. 2005 .
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 822
- Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
- Wikipedia: http://en.wikipedia.org/wiki/Tragacanth (Accessed Jan. 25, 2006)
- S.R.Trotman, E.R. Trotman, Textile Analysis, J.B. Lippincott Company, Philadelphia, 1932
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- Website address 1 Comment: "Violin Varnish Glossary" at www.violins.on.ca/luthier.vargloss.html