Animal glue or technical gelatin has many uses that depend on it’s gelling or on it’s surface properties. The most common use for animal glue is as an adhesive solution where its gap filling properties added to its great dry strength are its main advantages. However animal glue must penetrate the surfaces to be bonded so one must ensure that the penetration of the liquid occurs before the glue gels. Surfaces can be joined with animal glue if one of the surfaces is permeable to water. In practice animal glue is used hot and sufficiently so to ensure penetration before gelation. The rapidly developed tackiness of animal glue as it sets to a gel makes it useful in such application as sticking cloth to wood, bookbinding, in the manufacture of cartons on high speed machines and manufacture of “gummed” tape.
Other examples of its uses as an adhesive is in woodworking, cardboard case closing, match head bonding to the stick and the bonding of abrasives to paper for use as sandpaper.
The glue on drying forms a very strong film. This film forming property is used in paper seizing and cardboard manufacture and for decorative picture frame moldings.
Glue films are so strong that as they dry and shrink, if the glue is well keyed to glass the drying film rips some glass from the surface. This is the basis for the process called glass chipping and is also the reason why you never let glue dry in a glass container.
Animal Glue being a protein does not burn and this property is used to control the rate of combustion of dry match head formulations, as well as in fireworks and in firearm propellants. Animal glue solution gels on cooling and this property is used in retaining match heads on match sticks during the drying process and in the manufacture of printing machine rollers.
To prevent glue solutions from drying, polyhydric alcohol humectants can be added to the solution before gelation.
Finally, gelatin modifies the deposition environment (zeta potential) during electroplating allowing a smooth surfaced ingot to be formed in place of an ingot full of spikes, due to uneven electrolytic deposition of metal from solution. The glue also improves the efficiency and cost of deposition. In refining metal the glue is used as an additive in the electrolytic process. Especially used in refining copper.
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