Optical characterization of natural protective varnishes and their influences on perception of painted samples

Abstract

Interdependence between color and gloss is a concept well-known by artists, especially by old masters, but is not usually considered in material characterization. Indeed, measurement methods and definitions consider these two attributes individually. This research investigates how the available measurement methods for gloss and color (saturation) fit with corresponding perceptual qualities, glossiness and saturation. The definitions of both measured quantities, as well the measurement methodologies, were developed for reference materials (ceramic tiles for color and dark glass specimen for gloss) not representative of artwork materials and do not consider observation conditions similar with those adopted during exhibitions. The prediction of material appearance is recognized as one of the most important challenges in applied metrology, because appearance is the key to achieve effective exhibitions and consumers choices. The results of this study highlight that the two perceived qualities are mutually related, as well the measured quantities: gloss and saturation mutually interfere and the measurement methods and quantities are not uniform with the perceived qualities and the colorimetric coordinate C* no longer describes the perceived saturation.