Gloss meters and their handling procedures had to be internationally specified to allow comparison of measurement values. The angle of illumination is of high influence. In order to obtain a clear differentiation over the complete measurement range from high gloss to matte, 3 different angles, i.e. 3 different ranges, were defined:

In addition, there are industry specific applications for 45º and 75º measurement geometry.

In this case study 13 samples were visually ranked to high gloss and measured with the 3 specified angles.
In the steep slopes of the curves the difference between the samples can be clearly measured, while in the flat part the measurement geometry no longer correlates with the visual

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