The effect of size and distribution of inert pigment on the performance of organic coatings

Abstract

The paper aims to show how the performance of paint coatings is affected by their composition. Samples of two paint coatings, which had delaminated in service, were compared with the same type of paint applied to samples for the purposes of certification. The particle size distribution of the filler materials (inert pigments) affected the flow of resin and wetting of the particles. In both failed samples, large particles sizes had agglomerated creating voids and crevices, resulting in poor wetting by the resin. This poor wetting and inherent lack of bonding had resulted in their premature failure. Both equivalent laboratory samples had a much better particle size distribution, with a lower maximum particle size, resulting in inert pigment being well distributed through the paint layer. The paper concludes that tighter control over the sizes of additives in paint such as inert pigments within Standards is needed to ensure better performance.