title: Non-destructive micro-analytical differentiation of copper pigments in paint layers of works of art using laboratory-based techniques.
abstract: An unambiguous identification of pigments in paint layers of works of art forms a substantial part of the description of a painting technique, which is essential for the evaluation of the work of art including determination of the period and/or region of its creation as well as its attribution to a workshop or an author. Copper pigments represent a significant group of materials used in historic paintings. Because of their substantial diversity and, on the other hand, similarity, their identification and differentiation is a challenging task. An analytical procedure for unambiguous determination of both mineral-type (azurite, malachite, posnjakite, atacamite, etc.) and verdigris-type (copper acetates) copper pigments in the paint layers is presented, including light microscopy under VIS and UV light, electron microscopy with elemental microanalysis, Fourier transformed infrared micro-spectroscopy (micro-FTIR), and X-ray powder micro-diffraction (micro-XRD). Micro-Raman measurements were largely hindered by fluorescence. The choice of the analytical methods meets the contemporary requirement of a detailed description of various components in heterogeneous and minute samples of paint layers without their destruction. It is beneficial to use the combination of phase sensitive methods such as micro-FTIR and micro-XRD, because it allows the identification of both mineral-type and verdigris-type copper pigments in one paint layer. In addition, preliminary results concerning the study of the loss of crystallinity of verdigris-type pigments in proteinaceous binding media and the effect of lead white and lead tin yellow as highly absorbing matrix on verdigris identification in paint layers are reported.
authors.affiliation: Institute of Inorganic Chemistry of the AS CR, v.v.i., ALMA Laboratory, Husinec-Řež 1001, 250 68 Řež, Czech Republic. Electronic address: svarcova@iic.cas.cz.
authors.forename: Silvie
authors.initials: S
authors.lastname: Svarcová
authors.affiliation: Institute of Inorganic Chemistry of the AS CR, v.v.i., ALMA Laboratory, Husinec-Řež 1001, 250 68 Řež, Czech Republic; Academy of Fine Arts in Prague, ALMA Laboratory, U Akademie 4, 170 22 Praha 7, Czech Republic; Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2, Czech Republic. Electronic address: cermakova@iic.cas.cz.
authors.forename: Zdeňka
authors.initials: Z
authors.lastname: Cermáková
authors.affiliation: Academy of Fine Arts in Prague, ALMA Laboratory, U Akademie 4, 170 22 Praha 7, Czech Republic. Electronic address: hradilovaj@volny.cz.
authors.forename: Janka
authors.initials: J
authors.lastname: Hradilová
authors.affiliation: Institute of Inorganic Chemistry of the AS CR, v.v.i., ALMA Laboratory, Husinec-Řež 1001, 250 68 Řež, Czech Republic; Academy of Fine Arts in Prague, ALMA Laboratory, U Akademie 4, 170 22 Praha 7, Czech Republic. Electronic address: petrb@iic.cas.cz.
authors.forename: Petr
authors.initials: P
authors.lastname: Bezdička
authors.affiliation: Institute of Inorganic Chemistry of the AS CR, v.v.i., ALMA Laboratory, Husinec-Řež 1001, 250 68 Řež, Czech Republic; Academy of Fine Arts in Prague, ALMA Laboratory, U Akademie 4, 170 22 Praha 7, Czech Republic. Electronic address: hradil@iic.cas.cz.
authors.forename: David
authors.initials: D
authors.lastname: Hradil
mesh_terms: D000818:Animals; D003300:Copper / Q000032:analysis*; D007753:Laboratories; D010150:Paint / Q000032:analysis*; D010151:Paintings; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: D003300:Copper
keywords: Copper pigments; Infrared spectroscopy; Microanalysis; Model experiments; Paintings; Powder X-ray micro-diffraction