In most cases glue is indeed made from ingredients derived from animals though some glues like craft glue are water based and free of such ingredients. Glues containing animal products essentially contain the hides of animals or sometimes the skins of fishes (eisenglass) as well as fatty acids obtained from animals like pigs and are preferred over water based glues as they are more moisture resistant.
Some glue contains ingredients derived from animal parts like hooves and antlers; gelatin is also an ingredient used in glue which is derived from the hide and bones of animals like horses. Glue like Elmer's are synthetic ones manufactured from chemicals derived from petroleum products.
Hide based glue has a wide range of applications in various industries like the wood and furniture industry while a casein (milk protein) based glue is fast gaining popularity due to its adhesive properties even at extremely small amounts, in many industries
Some glue contains ingredients derived from animal parts like hooves and antlers; gelatin is also an ingredient used in glue which is derived from the hide and bones of animals like horses. Glue like Elmer's are synthetic ones manufactured from chemicals derived from petroleum products.
Hide based glue has a wide range of applications in various industries like the wood and furniture industry while a casein (milk protein) based glue is fast gaining popularity due to its adhesive properties even at extremely small amounts, in many industries