Skip to Content
Merck
  • Non-destructive micro-analytical differentiation of copper pigments in paint layers of works of art using laboratory-based techniques.

Non-destructive micro-analytical differentiation of copper pigments in paint layers of works of art using laboratory-based techniques.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy (2014-06-04)
Silvie Svarcová, Zdeňka Cermáková, Janka Hradilová, Petr Bezdička, David Hradil
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Germanium, chips, 99.999% trace metals basis
Sigma-Aldrich
Germanium, powder, −100 mesh, ≥99.99% trace metals basis
Sigma-Aldrich
Germanium, powder, −100 mesh, ≥99.999% trace metals basis
Sigma-Aldrich
Germanium, chips, 99.999% trace metals basis
Germanium, sheet, 6x6mm, thickness 1.0mm, polycrystalline, 99.999%
Germanium, sheet, 50x50mm, thickness 3.0mm, polycrystalline, 99.999%
Germanium, rod, 50mm, diameter 5mm, polycrystalline, n-type, 99.999%
Germanium, sheet, 10x10mm, thickness 0.6mm, single crystal, -111, 100%
Germanium, microfoil, 50x50mm, thinness 0.25μm, specific density 166.3μg/cm2, 6 micron aluminum permanent support, 100%
Germanium, sheet, 50x50mm, thickness 1.0mm, polycrystalline, 99.999%
Germanium, rod, 25mm, diameter 5mm, polycrystalline, n-type, 99.999%
Germanium, sheet, 25x25mm, thickness 3.0mm, polycrystalline, 99.999%
Germanium, disks, 15mm, thickness 1.0mm, polycrystalline, 100%
Germanium, rod, 6mm, diameter 6.0mm, single crystal, 100%
Germanium, sheet, 50x50mm, thickness 0.5mm, single crystal, 99.999%
Germanium, sheet, 10x10mm, thickness 0.5mm, single crystal, -111, 100%
Germanium, microfoil, 25x25mm, thinness 0.5μm, specific density 333μg/cm2, 6 micron aluminum permanent support, 100%
Germanium, sheet, 7x24mm, thickness 1.0mm, polycrystalline, 99.999%
Germanium, sheet, 25x25mm, thickness 1.0mm, polycrystalline, 99.999%
Germanium, rod, 25mm, diameter 2.0mm, polycrystalline, n-type, 99.999%
Germanium, sheet, 25x25mm, thickness 1.0mm, single crystal, 99.999%
Germanium, disks, 20mm, thickness 1.0mm, single crystal, 100%
Germanium, sheet, 10x10mm, thickness 0.25mm, polycrystalline, 99.999%