Additives to Prevent Coating Defects Caused by Film Dewetting

By C. Jim Reader, Evonik Corporation,

Many surface defects, such as fisheyes, edge pull, and retraction are caused when the liquid film dewets after application. Application of the coating by brush, roller, or spray may effectively force wetting and spread the film across the substrate, but defects may form soon after application. There is competition between the hydrodynamic inertia of the applied film and the interfacial tension forces that can cause the coating to dewet or retract.