Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings

A reduced set of measurement geometries allows the spectral reflectance of special effect coatings to be predicted for any other geometry. A physical model based on flake-related parameters has been used to determine nonredundant measurement geometries for the complete description of the spectral bidirectional reflectance distribution function (BRDF). The analysis of experimental spectral BRDF was carried out by means of principal component analysis. From this analysis, a set of nine measurement geometries was proposed to characterize special effect coatings. It was shown that, for two different special effect coatings, these geometries provide a good prediction of their complete color shift.

The authors are grateful to “Plan Nacional de Física” for funding this work (FIS2010-19756-E), to CSIC’s JAE Program, and the “European Social Fund” for awarding us a research trainee. This study was also supported by the Spanish Ministry of Economy and Competitiveness under the grant DPI2011-30090-C02-02 and the European Union.