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Title: The darkening of zinc yellow: XANES speciation of chromium in artist;s paints after light and chemical exposures

Abstract

The color darkening of selected brushstrokes of the masterpiece A Sunday on La Grande Jatte - 1884 (by Georges Seurat) has been attributed to the alteration of the chromate pigment zinc yellow. The pigment originally displays a bright greenish-yellow color but may undergo, after aging, darkening to a dull, ocher tone. We used XANES to probe the oxidation state of Cr on paint reconstructions, and show that color changes are associated with the reduction of Cr(VI) to Cr(III). Paint mixtures containing the pigment and linseed oil to mimic mixtures used in La Grande Jatte were subjected to artificial aging in the presence of light, SO{sub 2}, and variable air humidity - 50 and 90% relative humidity. High relative humidity led to the largest degree of Cr(VI) reduction whereas low relative humidity promoted light-induced alterations. These results are corroborated by visible reflectance measurements on the same laboratory samples and contribute to a better understanding of the chemical reactivity of chromate pigments, which are present in many historical works of art.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1034206
Resource Type:
Journal Article
Journal Name:
J. Anal. At. Spectrom.
Additional Journal Information:
Journal Volume: 26; Journal Issue: (5) ; 2011; Journal ID: ISSN 0267-9477
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; AGING; AIR; CHROMATES; CHROMIUM; CULTURAL OBJECTS; COLOR; HUMIDITY; LINSEED OIL; MIXTURES; OPTICAL PROPERTIES; PAINTS; PIGMENTS; VALENCE; ZINC; X-RAY SPECTROSCOPY

Citation Formats

Zanella, Luciana, Casadio, Francesca, Gray, Kimberly A., Warta, Richard, Ma, Qing, and Gaillard, Jean-François. The darkening of zinc yellow: XANES speciation of chromium in artist;s paints after light and chemical exposures. United States: N. p., 2012. Web. doi:10.1039/C0JA00151A.
Zanella, Luciana, Casadio, Francesca, Gray, Kimberly A., Warta, Richard, Ma, Qing, & Gaillard, Jean-François. The darkening of zinc yellow: XANES speciation of chromium in artist;s paints after light and chemical exposures. United States. doi:10.1039/C0JA00151A.
Zanella, Luciana, Casadio, Francesca, Gray, Kimberly A., Warta, Richard, Ma, Qing, and Gaillard, Jean-François. Wed . "The darkening of zinc yellow: XANES speciation of chromium in artist;s paints after light and chemical exposures". United States. doi:10.1039/C0JA00151A.
@article{osti_1034206,
title = {The darkening of zinc yellow: XANES speciation of chromium in artist;s paints after light and chemical exposures},
author = {Zanella, Luciana and Casadio, Francesca and Gray, Kimberly A. and Warta, Richard and Ma, Qing and Gaillard, Jean-François},
abstractNote = {The color darkening of selected brushstrokes of the masterpiece A Sunday on La Grande Jatte - 1884 (by Georges Seurat) has been attributed to the alteration of the chromate pigment zinc yellow. The pigment originally displays a bright greenish-yellow color but may undergo, after aging, darkening to a dull, ocher tone. We used XANES to probe the oxidation state of Cr on paint reconstructions, and show that color changes are associated with the reduction of Cr(VI) to Cr(III). Paint mixtures containing the pigment and linseed oil to mimic mixtures used in La Grande Jatte were subjected to artificial aging in the presence of light, SO{sub 2}, and variable air humidity - 50 and 90% relative humidity. High relative humidity led to the largest degree of Cr(VI) reduction whereas low relative humidity promoted light-induced alterations. These results are corroborated by visible reflectance measurements on the same laboratory samples and contribute to a better understanding of the chemical reactivity of chromate pigments, which are present in many historical works of art.},
doi = {10.1039/C0JA00151A},
journal = {J. Anal. At. Spectrom.},
issn = {0267-9477},
number = (5) ; 2011,
volume = 26,
place = {United States},
year = {2012},
month = {3}
}