Animal glue

Description

A strong, liquid adhesive derived from animal tissues. Animal glue primarily consists of gelatin and lower molecular weight residues of Collagen, Keratin, and Elastin. The primary amino acids in animal glues are: Glycine (24.7%), proline, Alanine (10.1%), Glutamic acid (9.7%), arginine (8.2%), and Hydroxyproline (7.4%) (Mills and White 1994). Gelatin (size) is similar to animal glue, but purer and better refined. Animal glue has been made from ancient times from bones, skins, muscles, and intestines of animals (fish, goats, sheep, goats, cattle, horses, etc.). These agglutinating materials are hydrolyzed and broken down in boiling water; the cooled solution yields a jelly-like substance which is gelatin or glue. The water soluble glue occurs in a wide variety of forms and colors ranging from transparent to opaque and white to brown. Glue is soaked in cool water to form a turbid jelly that will become clear and thinner with gentle heating. Glue will decompose and darken when it is boiled. Top-quality animal glues are made from rabbitskin, sturgeon bladders, and parchment clippings. Hide glues are used in the manufacture of wood joinery, book binding, gessoes, gilding, abrasive papers, gummed tapes, and matches. Bone glues are used as carton and box adhesives. Animal glues are commercially available as pellets, hot melts, or a liquid solutions (with a plasticizer or preservative).

Synonyms and Related Terms

glue; gelatin; colle animale (Fr.); adhésif animal (Fr.); colle forte (Fr.); cola animal (Port.); cola animal (Esp.); gelatina (Esp.); colla animale (It); colla di carnicci (It); colla cervona (It); colla di coniglio (It)

Examples include: isinglass; fish glue; bone glue; parchment glue; Cologne glue; calfskin glue; sazenbon nikawa; hide glue; rabbitskin glue; sturgeon glue; pearl glue; carpenter's glue; scotch glue

Risks

• Usually darkens with time.
• Susceptible to microbiological attack.

Physical and Chemical Properties

• Soluble in water (pH = 6.0-7.5).
• Insoluble in oils, waxes, organic solvents, ethanol.
• Fluoresces yellow in ultraviolet light.
• Density = ~ 1.27 g/ml
• Refractive Index = 1.516-1.534 (gelatin)

Resources and Citations

• M.Haupt, D.Dyer, J. Hanlan "An Investigation into Three Animal Glues" The Conservator, No. 14, pp. 10-16, 1990.

• J.Hubbard, "Animal Glues" in Handbook of Adhesives, I.Skeist (ed.), Van Nostrand Reinhold, New York, 1977, p.139-151.

• J.S. Mills, R.White, The Organic Chemistry of Museum Objects, Butterworth Heinemann, London, 1994.

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971

• Reed Kay, The Painter's Guide To Studio Methods and Materials, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1983

• Tom Rowland, Noel Riley, A-Z Guide to Cleaning, Conserving and Repairing Antiques, Constable and Co., Ltd., London, 1981

• Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982

• Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989

• Conservation Support Systems, Catalog, 1997

• Encyclopedia Britannica, http://www.britannica.com Comment: "Adhesive." [Accessed 3 Sept. 2004]

• Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000