What Is Glue Made From?
True glue – that is – traditional glue is made from the skin and bones of animals. The glue is extracted by boiling these materials in water. The strong adhesive qualities of the glue firmly bond together joints of furniture, book bindings and other objects.
Glue came into being when ancient tribes discovered that the bones, hides, skin, sinew, and other connective tissues from animals could be processed to remove collagen, the protein in these tissues.
The collagen was sticky and was useful for holding things together. Milk solids, known as casein and blood albumin can also be used as a basis for glue. Dried serum from cows’ blood yields albumin that coagulates (clumps together) when heated and it becomes insoluble in water.
Fish glue was also made from the heads, bones, and skin of fish, but this glue tended to be too thin and less sticky. By experimenting, early man discovered that the air bladders of various fish produced much more satisfactory glue that was white and tasteless. It eventually was named isinglass or ichthocol.
Not all glue, however, is made from animal bones and skin. The white casein glue used to mend pottery, for example, is made from milk. The glue on postage stamps is made from plant starch collectively called vegetable glues. These materials are dispersible or soluble in water and are usually made from the starches that compose many grains and vegetables.
The natural gums include agar, from colloids in marine plants, algin that is derived from seaweed, and gum arabic, an extract of the acacia tree (also known as the gum tree). The substance called marine glue is used to caulk seams, but it consists of tar or pitch and is not truly glue.
Epoxy is a kind of plastic glue. It forms bonds that are often stronger than the material it joins together.