The study of the effect of interfacial interactions on the mechanical performance of a selected automotive topcoat system has been undertaken. The investigation concerned interactions that arise in acrylic-melamine/pigment assemblies. The pigments were designed to have different surface treatments. Three types of TiO2 pigment, one type of C. I. Pigment Green 7, and a chrome oxide pigment were used in this research. Information regarding the surface characteristics of the pigments and also of the polymer was obtained by Inverse Gas Chromatography (IGC) technique. The pigments, at different particle volume concentrations, were dispersed into the polymeric matrix with the aid of their related additives. The cured coating samples were subjected to tensile stresses. The maximum stress that each sample withstood before breakage was recorded. Two different types of behavior were observed for coating composites that contained one of the pigment forms, at different particle volume concentrations. Finally, the data obtained from the IGC studies were used to support the results obtained from tensile testing. (c) 2006 Wiley Periodicals, Inc.