Unraveling the Mystery of the Lost Luminosity of A Sunday on La Grande Jatte

1. Unraveling the Mystery of the Lost Luminosity of A Sunday on La Grande Jatte Sherri Rukes (RET Participant), Francesca Casadio, Ben Myers, SujingXie, Katherine Faber National Science Foundation DMR-0520513 Seurat’s A Sunday on La Grande Jatte – 1884, one of the most notable works of the Art Institute of Chicago’s collection, was plagued by a loss of some of its luminosity within a few years of painting. This was thought to be due to changes in the zinc yellow (zinc-potassium-chromate) pigment. Greens turned to olive, while yellows transformed to an orange-red. Zinc yellow paint samples aged in sulfur-containing atmospheres (analogous to coal-burning environments of late 19th century France) were examined using transmission electron microscope, energy dispersive X-ray spectroscopy, and electron energy loss spectroscopy. Results confirmed that the yellow-to-orange transition of the surface layer could be triggered by a change in the acidity of the environment, altering the chromate-dichromate equilibrium (bottom right). This work is a part of the AIC-NU Collaboration on Conservation Science funded primarily by the Andrew W. Mellon Foundation. Cross-section of paint layers from A Sunday on La Grande Jatte – 1884 showing a discolored surface overlaying bulk zinc yellow, veredian green and lead white.