title: Casting light on the darkening of colors in historical paintings.
abstract: The degradation of colors in historical paintings affects our cultural heritage in both museums and archeological sites. Despite intensive experimental studies, the origin of darkening of one of the most ancient pigments known to humankind, vermilion (α-HgS), remains unexplained. Here, by combining many-body theoretical spectroscopy and high-resolution microscopic x-ray diffraction, we clarify the composition of the damaged paint work and demonstrate possible physicochemical processes, induced by illumination and exposure to humidity and air, that cause photoactivation of the original pigment and the degradation of the secondary minerals. The results suggest a new path for the darkening process which was never considered by previous studies and prompt a critical examination of their findings.
authors.affiliation: ALGC, Research Group General Chemistry, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels, Belgium and EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Da Pieve
authors.forename: C
authors.initials: C
authors.lastname: Hogan
authors.forename: D
authors.initials: D
authors.lastname: Lamoen
authors.forename: J
authors.initials: J
authors.lastname: Verbeeck
authors.forename: F
authors.initials: F
authors.lastname: Vanmeert
authors.forename: M
authors.initials: M
authors.lastname: Radepont
authors.forename: M
authors.initials: M
authors.lastname: Cotte
authors.forename: K
authors.initials: K
authors.lastname: Janssens
authors.forename: X
authors.initials: X
authors.lastname: Gonze
authors.forename: G
authors.initials: G
authors.lastname: Van Tendeloo