Dextrin

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Description

A water soluble polysaccharide produced by the hydrolysis of starch. Patented in 1867, dextrin is produced when starch is hydrolyzed with dilute acid and heat, then neutralized with alkali. Pure dextrin is a white, amorphous powder that has a sweetish taste. It is used as an adhesive for envelopes, gummed paper, postage stamps, and mounting photographs. Dextrin is also used for sizing paper and textiles, for printing inks, as a thickening agent, and as a paint binder in poster paints and cheap tempera colors. Dextrin is sensitive to moisture, weathers poorly, and is susceptible to biodegradation. Two forms of impure or partially hydrolyzed dextrin are also available:

- British gum: a dark, brown powder that forms a tacky adhesive in warm water.

- Canary (yellow) dextrin: a water-soluble yellow powder.

Synonyms and Related Terms

dextrine (AAT preferred); starch gum; amylin; British gum; gommeline; vegetable gum; artificial gum; leiocom; sago dextrin; tapioca dextrin; canary dextrin; starch syrup; Dextrine (Deut.); dextrine (Fr.); dekstryna (Pol.)

Other Properties

Soluble in hot water. Insoluble in ethanol, ether.

Fluoresces a blue-white in ultraviolet light.

Iodine gives a red to blue color.

Sources Checked for Data in Record

  • R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966 Comment: iodine gives red to violet color
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 263
  • 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
  • Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986
  • Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
  • George Savage, Art and Antique Restorer's Handbook, Rockliff Publishing Corp, London, 1954
  • Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989