Objectively measure mottling of effect coatings with the new cloud-runner

April 12, 2011 - PRLog -- Metallic and effect finishes are of great popularity in the automotive industry. The orientation of the effect pigments (e.g. alu flakes) is very 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 which is especially noticeable on large body panels. Therefore, the surface quality needs to be analyzed over a large sample area. Up to now mottling was evaluated mainly visually and so the perceived results have been strongly dependent on the auditor and the different light conditions.

Production control as well as process optimization require objective measurement data, which furthermore allow defining tolerances. BYK-Gardner has developed a new portable solution to quickly scan the surface of a large area. The cloud-runner objectively measures the lightness variation at different detection angles simultaneously, as the visibility of mottling is also dependent on the viewing angle. The measurement signal is filtered in different mottling sizes and a “Mottling index” is calculated. The higher the measured value the more obvious is the mottling effect. Thus, target values can be specified for batch approval and process control.

Due to the scroll-wheel, the cloud-runner is very easy to operate. The large display offers enough space for all statistic data. The recorded measurement series can be transferred to a PC via a docking station, which also serves for charging the battery. The new software smart-chart offers flexible analysis functions and enables professional documentation of the measured quality.

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BYK-Gardner is a worldwide partner of the automotive, paint and plastic industries for quality control testing of color, appearance and physical properties.