The adhesion of objects is realized by the pull force between the polymer in the glue. In glue, water is the carrier of medium and high molecular weight, which is carried by water and slowly immersed into the tissue of the object. When the water in the glue disappears, the polymer in the glue will tightly combine the two objects by relying on the mutual pull.

Glue is an intermediate connecting two kinds of materials, most of which are water agents. It belongs to fine chemical industry and has a wide range of types. It is mainly classified by adhesive, physical form, hardening method and material of the adhesive.