Before we continue, we ought to learn a little of the language of pressure sensitive adhesives. So here are some simple explanations of a few basic terms.
Adhesion, is a measure of the bond strength existing between the adhesive and the surface to which it is applied. It is measured by determing the force necessary to break the bond. With pressure sensitive tapes, this is done by peeling the tape at a standard rate and temperature from a standard surface.
Tack, is a measure of the ease with which an adhesive can wet out a surface under extremely low pressures. A High tack tape, therefore would build up to a maximum adhesion in a minimum of time. There are many test methods for tack, none of which is fully accepted by the industry. One simple way is to measure the distance traveled by a free-rolling steel ball along the tape´s surface.
Cohesion, is a measure of international strength of an adhesive; simply, it is that force required to tear an adhesive in two. By designing an adhesive in which the cohesion is much higher than its adhesion, this ensures no mass transfer when the tape is removed.
Note: This material is an excerpt from Shuford Literature.