Measurement and control of mottling in automotive effect finishes

摘要

Today's quality requirements for automotive finishes, in regard to colour and appearance, are very high, as it is proven that "the first impression" establishes lasting perceptual quality opinions extending beyond design and paint appearance. Therefore, the exterior finish of a car body and its add-on parts should be perfectly matching in colour and appearance.Uniformity was, and still is, the most important criteria for perceived quality. For years, automotive manufacturers have assessed "mottling" visually - some have used panel sets with various degrees of mottling to assist their visual evaluation. But only when phenomena can be objectively measured can one control and optimize it. Cloudiness, also referred to as mottling, is lightness or colour variations which is most obvious on light metallic finishes. It can be caused by formulation incompatibilities as well as variations in application parameters. For example, film thickness variations of the basecoat or flake disorientation can lead to various cloud sizes resulting in a non-uniform appearance.