PROCEEDINGS ARTICLE | March 16, 2015
Proc. SPIE. 9398, Measuring, Modeling, and Reproducing Material Appearance 2015
KEYWORDS: Visible radiation, Statistical analysis, Optical properties, Reflection, Ions, Coating, Resistance, Reflectivity, Light sources and illumination, Analytical research
The spectral reflectance of different samples of three different hues, (red, green, blue) with four different protective
varnishes was measured in 8/d condition and with a goniometer equipped with a spectrometer. The samples are
representative of hue and varnishes typically used in works of arts, the characterization was performed to test how the
different gloss finishing induced by transparent varnishes affect the spatial distribution of the luminance coefficient in
typical lighting arrangements for exposition of works of art. Nowadays the most used transparent protective varnishes
are matt or glossy, natural or synthetic. The choice within them is usually made looking at mechanical, chemical (also in
term of removal) and protective properties. Varnishes optical properties investigation on saturation and gloss alteration
of the perceived artifacts are not usually investigated. Expected results of this research include: analysis of influences on
color appearance of protective varnish according to the condition of illumination and observation, suggestion of new
additional criteria for varnish selection and lighting set up exposition and reliability of 8/d measurements condition, that
is a typical measurement set-up of portable instruments. Our results showed that natural varnishes are more able to
change the gloss of the surfaces than synthetic ones, because the shape and intensity of the specular peak for glossy and
matt natural varnish are very different. Both synthetic and natural varnishes have different behaviors at 30° or 60° light
incidences: at 30° of incidence all samples have smaller variations, while at 60° of incidence the variations are larger,
and for some samples the achromatic point is reached.
