Adhesion's the tendency of certain dissimilar molecules to cling together due to attractive forces. Mechanisms of adhesion Five mechanisms have been proposed to explain why one material sticks to another: Mechanical adhesion Adhesive materials fill the voids or pores of the surfaces and hold surfaces together by interlocking. Sewing forms a large scale mechanical bond, velcro forms one on a medium scale, and some textile adhesives form one at a small scale. This's similar to surface tension. C… (More on Adhesion)