A Technical Study of John Singer Sargent's Portrait of Madame Pierre Gautreau

Elemental and Molecular Segregation in Oil Paintings due to Lead Soap Degradation

“…The saponification observed at the bottom of the original PbSn yellow (layer 4) in the paint cross-section shown in Figs 1 and 2A may be explained by a larger supply of free fatty acids in that region. Similar partial formation of soaps in paint layers has been previously reported and ascribed to the migration of fatty acids from medium-rich paint layers above or beneath the saponified paint layer 5 , 33 . To characterize these soap aggregates further, the area indicated by a yellow square in Fig.…”

Identification of artistic materials in paintings and drawings by Raman spectroscopy: some challenges and future outlook

“…XRD requires the soaps be crystalline but the technique is also limited by the facts that most of the characteristic lines for various heavy metal soaps are at low angles, so the instrumentation must be able to resolve lines in this region, and that the characteristic lines at higher angles are much weaker . On the other hand, Raman spectroscopy allows to identifying and localizing both crystalline and amorphous soaps in the stratigraphy of paint cross sections; however discrimination among carboxylates of the same metal with different fatty acids in samples removed from works of art may be difficult . Otero et al used a combination of Raman spectroscopy, FTIR, and PCA in group of 22 metal carboxylates synthetized in the laboratory, and further characterized by XRD, and found that Raman spectroscopy allows determining the fatty acid carbon chain length, that FTIR enables the identification of the cation coordinated to the carboxylate group/s, and that PCA facilitates the fast and accurate discrimination and identification of the different carboxylates in the model samples and in paint samples removed from 19 th century paintings.…”

207Pb and119Sn Solid-State NMR and Relativistic Density Functional Theory Studies of the Historic Pigment Lead–Tin Yellow Type I and Its Reactivity in Oil Paintings

“…Lead–tin yellow type I (LTY-I) was used as a pigment in European paintings from at least the second quarter of the 15th century until the first half of the 18th century. , This pigment is an important source of lead ions and has been implicated in the formation of lead carboxylates (commonly referred to as lead soaps), second only to basic lead white, 2PbCO 3 ·Pb(OH) 2 . Lead soap formation is a process that has been observed in hundreds of oil paintings and manifests itself in the formation of aggregates 100–200 μm in diameter that distort the paintings’ surface textures, by an increased transparency of the paint films, or by the formation of surface crusts. − In recent years characterizing the reactivity of lead stannate, Pb 2 SnO 4 , with fatty acids has been increasingly recognized as a key issue to understand soap formation in paintings. , …”