Uniform and consistent color is essential to achieve the impression of a high quality finish and to avoid customer complaints. Special effect coatings play a dominant role in automotive and other applications as they make an object "alive" and distinctively appealing. Over the last decades new effect pigments have been constantly developed with increasingly complex color shift and appearance which can no longer sufficiently be described with conventional instrumentation.
The first type of effect pigments introduced were aluminum flakes in metallic coatings. Dependent on the viewing angle they show a light-dark flop and thus, accentuate the curved profile of an object.
To fully characterize this effect with instrumentation, measurements have to be done at different angles (fig. 2). It was determined that a minimum of three and best five viewing angles are needed to provide sufficient information on the goniophotometric characteristics of a metallic finish.The measurement geometry for multi-angle measurement is specified by aspecular angles.