Gloss Appearance of Metallic Coatings

The visual glossiness of paint samples is known to depend on the type of lighting, but there is a lack of quantitative studies. This is particularly true for effect paints such as metallic coatings. We investigate factors influencing gloss appearance using paint samples varying in color and glossiness. Eight observers assessed glossiness for 119 samples under two different types of lighting using the psychophysical method of magnitude estimation. Our results confirm that for high‐gloss samples, distinctness‐of‐image dominates gloss perception, whereas contrast gloss dominates for low‐gloss samples. We show that the critical glossiness level separating these cases depends on the type of lighting. We report a repeatability for gloss appearance of 6.9 Gloss Units for solid colors observed inside a light booth. Similar values were found for metallic paints and for observations under diffuse lighting. Our results show that visual glossiness assessments are highly inaccurate for dark matte paint samples with lightness value 20 < L* < 40 and glossiness 20 < Gloss60 < 50. Deviations often larger than 10 Gloss Units occur as visual overestimations of glossiness for observations in both light booth and diffuse room. For the diffuse room, the overestimations gradually become underestimations for lighter, glossier paint samples with L* > 40 and Gloss60 > 50 Gloss Units. We find that metallic colors closely follow the same trends as solid colors. Quantitatively, the influence of the metallic character of coatings on gloss perception is smaller than the influence from sample color (lightness) and from the type of lighting.