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Time-of-flight secondary ion mass spectrometry (ToF–SIMS) has recently been shown to be a valuable tool for cultural heritage studies, especially when used in conjunction with established analytical techniques in the field. The ability of ToF–SIMS to simultaneously image inorganic and organic species within a paint cross section at micrometer-level spatial resolution makes it a uniquely qualified analytical technique to aid in further understanding the processes of pigment and binder alteration, as well as pigment–binder interactions. In this study, ToF–SIMS was used to detect and image both molecular and elemental species related to CdS pigment and binding medium alteration on the painting Le Bonheur de vivre (1905–1906, The Barnes Foundation) by Henri Matisse. Three categories of inorganic and organic components were found throughout Le Bonheur de vivre and co-localized in cross-sectional samples using high spatial resolution ToF–SIMS analysis: (1) species relating to the preparation and photo-induced oxidation of CdS yellow pigments (2) varying amounts of long-chain fatty acids present in both the paint and primary ground layer and (3) specific amino acid fragments, possibly relating to the painting’s complex restoration history. ToF–SIMS’s ability to discern both organic and inorganic species via cross-sectional imaging was used to compare samples collected from Le Bonheur de vivre to artificially aged reference paints in an effort to gather mechanistic information relating to alteration processes that have been previously explored using μXANES, SR-μXRF, SEM–EDX, and SR-FTIR. The relatively high sensitivity offered by ToF–SIMS imaging coupled to the high spatial resolution allowed for the positive identification of degradation products (such as cadmium oxalate) in specific paint regions that have before been unobserved. The imaging of organic materials has provided an insight into the extent of destruction of the original binding medium, as well as identifying unexpected organic materials in specific paint layers.

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Changes in the formulation of pigments and paint binders and the presence of additives used in the history of painting can complicate the interpretation of analytical data and may influence the characterization of the materials used in artworks. The limitations of the common analytical tools used to identify potential paint components including metallic driers, pigments, and the inorganic substrates of lake colors may also make analysis more difficult. X-Ray Fluorescence (XRF) spectroscopy is a common non-destructive technique used to collect inorganic elemental information from artworks. Advancements in XRF technology now permit the gathering of data from multi-layered paint systems and scanning technology can help characterize pigments across the entire surface of an artwork. These tools require an even greater understanding of the potential materials in an artwork to avoid misinterpretation of the data. The authors tested XRF’s ability to characterize lead, manganese, and cobalt driers. The presence of metallic driers could have an impact on the interpretation of the inorganic components in paint films. Lake pigment substrates often contain aluminum, tin, and calcium salts. The detection of these ions was also studied. Finally, the XRF detection of aluminum in lapis lazuli samples was assessed. These three groups of materials were also mixed with driers and/or other pigments to determine whether the presence of additional metal ions inhibited the detection of the characteristic elements. The authors used a Bruker ArtTax Micro XRF and a handheld Bruker Tracer III-SD XRF unit with and without a vacuum or helium purge for these experiments.

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