When we were kids, we visited art museums to examine all of the big, bright paintings with wide-eyed wonder. Today, some of those paintings aren’t as bright as they used to be.
In a new study, an international team of scientists have discovered exactly why the bright yellow pigment favored a century ago is turning to a drab beige.
It turns out that the original chemical compound, cadmium sulphide, which is a highly water-insoluble and bright yellow, is subject to a light-induced oxidation process that turns it into a colorless, water-soluble cadmium sulphate. Yikes! This is not a good thing, since it was favored by so many of the Impressionist, post-Impressionist, and early modernist masters. Henri Matisse is just one of the many artists who used it in their works—works that are fading fast.
“The results of this study reveal how critical it is to understand not only the chemistry of the discolored paint, but also the chemistry used to prepare the paints that were available to the turn of the 20th-century’s most enduring artists,” said Winterthur Museum‘s Senior Scientist Jennifer Mass, Ph.D. “Our study points the way toward several important areas requiring further investigation, among the most critical of which is developing a protocol for identifying the ‘at risk’ paintings that are in their earliest stages of degradation, even before it is visible to the naked eye, so that such works can be placed in the proper display environments that will prevent their degradation from worsening.”
Mass led the international team, who used X-ray diffraction, X-ray absorption spectroscopy, X-ray fluorescence analysis, and infrared microscopy to study the fading pieces at the European Synchrotron Radiation Facility in Grenoble, France. The study specifically looked at Matisse’s The Joy of Life, although the discoveries could also apply to other Matisse works, as well as those by James Ensor and Vincent Van Gogh.
“As a chemist, I find it striking that in paintings of different artists and different geographical origins that (presumably) were conserved for circa 100 years in various museum conditions, very similar chemical transformations are taking place,” said Koen Janssens, chemistry professor at the University of Antwerp in Belgium. “This will allow us to predict with higher confidence what may be happening to these works of art in the coming decades.”
The ESRF said that museum scientists over the past decade have estimated that “this disfiguring phenomenon is affecting billions of dollars of our global cultural heritage.” The findings can help them identify and help preserve “at risk” paintings, as well as learn how to properly digitally restore damaged paintings and create a computer-generated image that reveals the artists’ original intent.
“When we combine our findings on the works of Henri Matisse with the studies carried out on works by Vincent Van Gogh and James Ensor, the understanding of their degradation gives us a road map to guide us in the preservation of these works,” Mass said. “It also provides us with the information needed to digitally restore the damaged paintings, creating a computer-generated image that reveals the artists’ original intent.”
The study is featured in an article, “2D X-ray and FTIR micro-analysis of the degradation of cadmium yellow pigment in paintings of Henri Matisse,” in the June 2015 issue of Applied Physics A.
