Abstract
There are no established and accepted techniques available for accurate characterization appearance changes brought about by scratch and mar damage. Scratch and mar resistance is related to the ability of a coating in resisting deformation. The appearance change is brought about by surface roughening which in turn leads to a reduction in gloss and reflectivity. This paper focuses on the measurement of the appearance of coating by image analysis and gloss measurement.
Highlights
Materials durability studies of coatings involve precise monitoring and meaningful analysis of the coating's appearance and surface defects^^ '^ \ The current techniques that monitor and analyze coatings are oftentimes deficient in accurate characterization of the coating's appearance
While photometric devices can measure the amount of light reflected from the target area of an object, the spatial composition of the target area is still at a loss
Scratch and mar resistance testing of automotive coatings is done routinely and used as the basis for comparison of a coating s mechanical performance. Both wet and dry mar testing protocols have been used^^^^ to inflict scratch and mar damage similar to that encountered in the field
Summary
Materials durability studies of coatings involve precise monitoring and meaningful analysis of the coating's appearance and surface defects^^ '^ \ The current techniques that monitor and analyze coatings are oftentimes deficient in accurate characterization of the coating's appearance. This article describes: 1) shortfalls of the conventional photometric appearance measurement techniques in weathering and durability applications, 2) an overview of a digital image capture/processing/analysis system, 3) the applicability of the. When the surface is not optically smooth, the light will be reflected from the surface at angles greater than 0° (see figure 1) This scattering effect of reflected light is most beneficial in examining surfaces in the presence of dirt, scratches, and streaks (common in weathered surfaces). These characteristics render conventional gloss measurements unreliable. The measurements made for each are described separately below when discussing each application
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