London dispersion forces arise from instantaneous dipoles between two nonpolar molecules close together.
The strength of adhesion by the dispersive mechanism depends on a variety of factors, including the chemical structure of the molecules involved in the adhesive system, the degree to which coatings wet each other, and the surface roughness at the interface.
Thus, two materials that wet well and have a large amount of surface area in contact will have stronger intermolecular attractions and a larger adhesive strength due to the dispersive mechanism.
Thus, more intermolecular interactions at closer distances can arise, yielding stronger attractions and larger adhesive strength.
Once the roughness becomes larger, on the order of 10 micrometres, the coating can no longer wet effectively, resulting in less contact area and a smaller adhesive strength.
When a rigid punch[jargon] with a flat but oddly shaped face is carefully pulled off its soft counterpart, the detachment does not occur instantaneously.
Instead, detachment fronts start at pointed corners and travel inwards until the final configuration is reached.