Adhesives and related products are in a period of fast growth. A decline in mechanical fastening combined with a rise in new products formulated with new materials has created a demand for these products. The demand is not concentrated in one or two industries, but all areas of manufacturing. We first start with the basics of tack:

Tack is defined as the ability of a material to form a strong bond with another surface for a short time under light pressure. Tack is a property critical to pressure sensitive adhesives and related products where a temporary bond is desired. Examples include labels, tapes and patches. The fundamental criterion for tack is surface wetting, interdiffusion, and cohesive strength (or green strength)

NuSil Technology tests tack via two methods currently: surface tack testing and blunt probe tack testing. Surface tack testing utilizes a ½ inch flat foot that is placed on a level sample of adhesive. A weight is placed on top of the foot apparatus for a defined period of time and removed. The force it takes to remove the foot from the adhesive is recorded. The NuSil Technology test method for this procedure is TM103 and references ASTM D429 Method D.

Blunt probe tack testing is a more sensitive test that utilizes a ¼ inch diameter hemispherical probe that is mechanically forced into and withdrawn from a sample of adhesive. The force required to remove the probe is recorded for this test. The NuSil Technology test method for this procedure is TM122 and references ASTM D 2979.

The challenge in adhesion testing is determining which method produces a result that can be best correlated to the end application. Engineers need to work with material manufacturers to determine the best ASTM based methods that correlate with the end application.