Modern measurement of effect pigments - useful and useless geometries

 
A look at the history of the portable measuring instruments shows that geometries for measuring effect pigments were determined partly arbitrarily. In the mid-nineties, the classical illumination angle at 45 ° was first combined with three difference angles (aspecular) of gloss. Due to patent rights, two further aspecular angles were then placed between these angles. In 2008, ASTM published a Standard Test Method describing the geometries for measuring interference pigments. In addition to an additional difference angle in the trans position to the gloss angle, a second illumination angle at 15 ° was also defined. This results in a variety of measurement geometries, which are only partially useful for determining the interference colors. Other measuring geometries are superfluous because they hardly contribute to the characterization and identification. This presentation deals with the different geometries of the current measuring instruments and sheds light on their necessity.