Gum tragacanth

== Description ==
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
[[[SliderGallery rightalign|MFA- Gum Tragancanth.jpg~FTIR]]]
==Risks ==
* Combustible. 
* 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.
CAS 	9000-65-1
Density	1.25-1.384 g/ml
==Resources and Citations==
* R.Newman, M.Serpico, "Adhesives and Binders" in Ancient Egyptian Materials and Technology, P.Nicholson, I.Shaw (eds.), Cambridge University Press, 2000, p. 475-494.
* R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
* Reed Kay, The Painter's Guide To Studio Methods and Materials, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1983
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
* 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
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
* I.W. Cottrell, J.K. Baird, gums chapter
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* John S. Mills, Raymond White, The Organic Chemistry of Museum Objects, Butterworth Heineman, London, 2nd ed., 1994
* Website address 1 Comment: "Violin Varnish Glossary" at www.violins.on.ca/luthier.vargloss.html
Category:Materials database