The regular white glue most students know so well is made up of a variety of chemicals called polymers. These polymers are long strands that are either sticky or stretchy. Glue manufacturers have to find just the right combination of sticky and stretchy polymers to make the best glue.White glue also contains water. Water acts as a solvent that keeps the glue liquid until you want it to stick.When you put glue on a piece of paper, the solvent — water — is exposed to air. The water eventually evaporates (changes from a liquid to a gas). As the water evaporates, the glue dries and hardens. All that's left are the sticky polymers that hold things together. This process is called mechanical adhesion.