The portable cloud-runner instrument is now offered to measure mottling at the paint line. Metallic and effect finishes are popular in the automotive industry. The orientation of the effect pigments is critical and is dependent on the “robustness” of the paint formulation, as well as variations of process parameters. Thus, irregular spots of varying lightness, also called mottling or cloudiness, may occur. Theses patches are most obvious on light metallic colors. Typical causes can be a disorientation of the metallic flakes and/or film thickness variations of the basecoat. Mottling is a very undesirable effect that is especially noticeable on large body panels. Therefore, the surface quality needs to be analyzed over a large sample area.

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