Intrinsic limits of reflectance spectroscopy in identifying pigments in paint layers

The study of pigments is of fundamental importance for authentication and restoration purposesof painted artworks. To this aim reflectance spectroscopy has been widely studied on samples and in a number of real cases. A number of valuable efforts have been dedicated to this quest; however,the identification of a pigment on a painting surface by means of reflectance spectroscopy appears to bepossible only in very few casesalso due to the fact that artist materials are often mixed. In this paper we review a number of relevant works and present results on a new set of test samples especially produced for exploring the possibilities of reflectance spectroscopyon pigment mixtures. We also include a case study of a real painting.