The effect of clear coat and basecoat interdiffusion on the appearance of automotive coating system

In this study, the possible effect of clear coat and basecoat interdiffusion on final appearance of the coating system is examined. The clear coat was applied at different thicknesses wet on wet on the basecoat. The orientation of aluminum flakes was evaluated by the orientation distribution and the flop index measured by the goniospectrophotometer. The gloss, haze, specular reflectance, distinctness of image and orange peel attributes were measured by the goniophotometer and the orange peel analyzer, respectively. The obtained results indicated that the clear coat thickness had no influence on the orientation distribution and the flop index, while the other measured appearance attributes were under influence of clear coat thickness. Optimal appearance attributes were achieved at 75.3 ± 1.8 μm of the clear coat. In addition, the texture analysis was performed on the images of the coatings. No variation in texture was found by increasing the clear coat thickness. Based on the appearance measurement results, it seems that interdiffusion of the basecoat and clear coat has negligible impact on the appearance of the coating system.