This is the third in a series of four articles on coatings additives. Previous articles have covered rheology modifiers and defoaming. The fourth article will cover pigment dispersants and the pigment dispersion process. This article discusses surface tension modifiers. In particular, I will only be covering the surface tension of liquid coatings on solid substrates in this article.
Surface tension is the macroscopic effect of the cohesive forces between molecules to minimize the surface area. Surface tension is defined as the force per unit length exerted by a stretched liquid membrane. Wetting out a substrate is the interaction of the surfaces of the liquid and the substrate, or the surface tensions of both. This is often reported as Dynes/cm and are the units I will be using.