What is dyne level testing, and why is it necessary for proper film adhesion?

Dyne level testing is a method widely used to test the treatment level of plastic films intended for printing, laminating, and coating. Test results are based on how varying surface tension solutions react when applied to a non absorptive surface.

If a given solution wets the surface, its dyne level is lower than the substrate's; if, instead, it rapidly forms beads; its dyne level exceeds that of the substrate. This result would produce a poor adhesion level between substrate and film. Thus for most solvent based printing, plastics need to treated to a surface dyne level of 36 - 40 dynes/cm water based inks usually require 40 - 44 dynes/cm; some of laminating and coating applications require surface energies of 50 dynes/cm or more.