Estimation of critical pigment volume concentration in latex paint systems using gas permeation

Critical pigment volume concentration (CPVC) is a fundamental transition characteristics at which properties of a coating changes significantly. At this point voids begin to introduce through the film. Many methods have been proposed to determine the CPVC of indoor latex paints based on the change of a film property. These methods are mostly time consuming. In this research, a new method has been proposed based on permeability of coating and it is compared with wet scrub resistance method which is a mechanical one. Wet scrub test is based on the void contents and the strength of the interfaces of latex particles existing in the film. In contrast, permeation test is only based on the void contents through the film and therefore it is more consistent with the definition of CPVC. It was observed that this new method is several times faster and less sensitive to aging or annealing.