Animal glue

An animal glue is an adhesive that is created by prolonged boiling of animal connective tissue.

These protein colloid glues are formed through hydrolysis of the collagen from skins, bones, tendons, and other tissues, similar to gelatin. The word "collagen" itself derives from Greek κόλλα kolla, glue. These proteins form a molecular bond with the glued object.

Stereotypically, the animal in question is a horse, and horses that are put down are often said to have been "sent to the glue factory". However, other animals are also used, including rabbits and fish.

Animal glue has existed since ancient times, although its usage was not widespread. There is evidence that the Neanderthals used glues in their paints to guard their works from moisture, and some horse tooth glues can be dated back nearly 6000 years, but no written records from these times can prove that they were fully or extensively utilized.

The first known written procedures of making animal glue were written about 2000 BC. Between 1500–1000 BC, it was used for wood furnishings and mural paintings, found even on the caskets of Egyptian Pharaohs. Evidence is in the form of stone carvings depicting glue preparation and use, primarily utilized for the pharaoh’s tomb’s furniture. Egyptian records tell that animal glue would be made by melting it over a fire and then applied with a brush.

Greeks and Romans later used animal and fish glue to develop veneering and marquetry, the bonding of thin sections or layers of wood. Animal glue, known as taurokolla in Greek and gluten taurinum in Latin, were made from the skins of bulls in antiquity. Broken pottery might also be repaired with the use of animal glues, filling the cracks to hide imperfections.

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