On-site contactless surface analysis of modern paintings from Galleria Nazionale (Rome) by reflectance FTIR and Raman spectroscopies

Seven artworks representing the diversity of paints used around 1960s and created by German Italian painters (J. Albers, A. Bonalumi, L. Boille, T. Scialoja M. Schifano) were studied on-site at Galleria Nazionale d'Arte Moderna (Rome) with mobile instruments. We present a methodology based on Specular Reflectance Infrared Spectroscopy (SR-FTIR) adapted to unvarnished paintings. Complementary measurements have been performed Raman spectroscopy. Characteristic bands regarding as-recorded infrared reflectance spectra Kramers-Kronig Transformation-converted absorbance are identified according literature reference recorded representative commercially available paints. To distinguish different binders SR-FTIR, we propose spectroscopic markers as comparison intensity carbonyl band 1730-1735 cm−1 ~1160 (for acrylic), ~1230 PVAc), 1270 alkyds). On other hand, oil/resin characterized intense thin νCH2, νCH3 IR absorption 2920-2850 cm−1, combined an 1260 characteristic concave cradle shape (between ca. 1750 cm−1). The results obtained establish relevance implemented non-invasive spectroscopy analytical approach successfully identifying acrylic, vinylic, oil media enamel paints, or without opacifiers, which is supplemented analyses for pigment identification.