(Inside Science) -- In the last decade, art conservators -- the people who protect and preserve works of art -- have begun practicing complicated science. Now they can tell more stories of the secret lives of artists, the chemistry behind great works, and why many of the most famous masterpieces no longer look anything like they did when they were painted.
They also discovered that one form of paint may reduce some of the great works of modern and impressionist art into white canvases with smudges.
In interviews and talks at the AVS International Symposium and Exhibition in Baltimore last week, scientist-conservators told how analyzing great works with devices only physicists and chemists could love -- synchrotron radiation sources, ultraviolet-induced fluorescence, high resolution, and XRF multispectrography -- lifts the mysteries off some paintings and can produce stories worthy of novels. Most of the paintings discussed were by impressionists and modern artists who worked from the end of the 19th century into the mid-20th. They hang in some of the most prestigious museums in the world.
For instance, in 1901, Pablo Picasso was living in abject poverty in a studio in Paris when one day he met a young woman he wanted for a model. When she agreed, Picasso grabbed a canvas already in his studio and went to work. The result is a painting called The Blue Room, now a cornerstone of the Phillips Collection in Washington, D.C. It is a masterpiece of Picasso’s “blue period” so-called because he used the color predominantly in a series of paintings.
This one showed the model, nude, bathing herself in the studio. But, when the scientist-conservators brought in some of the new tools of modern physics and chemistry there was a surprise.
Under the picture of the woman was an entirely different painting. Picasso had painted over it.
It is not unusual for artists to do various renditions of the painting they have in mind, like a writer doing drafts, but this was an entirely different work, a portrait of a man with a mustache and bowtie leaning on his hand. Analysis shows it was also Picasso’s work, said Patricia Favero, a Phillips conservator.
“We know nothing about who it is or why it was painted in the first place,” she said, “or why it was painted over.” The mystery, like something in a Tracy Chevalier novel, grows. Did he take the canvas because he could not afford a new one? Who was the man in the portrait? Was Picasso in love or lust with the woman?
Most likely, Favero said, Picasso was inspired to paint the woman and couldn’t wait. But whatever the reason, he was surely in a hurry: usually when painters over paint a canvas they lay a white foundation first. Picasso simply painted over the portrait.
And the blue in Picasso’s blue period was Prussian blue, a pigment made largely of iron-based molecules, chemists determined. The Phillips is still analyzing the painting.
That high-tech equipment found its way into art museums reflects changes in the profession, said Favero.
“We have backgrounds in a number of different areas,” she said. “Studio art and art history, and training in chemistry, organic chemistry, and various analytical techniques.”
Many of the tests involve taking a tiny flake from the painting, something no bigger than the period at the end of a printed sentence, usually from a part of the painting where it is less likely to be noticed. That goes into the analyzing devices.
Newer techniques are non-invasive. Phillips even sent The Blue Room, a painting worth several million dollars, to Ithaca, New York, to analyze it under Cornell University’s Maia synchrotron beam.
Many paintings are deteriorating and the villain, the scientists have discovered, is a paintmade with cadmium sulfide, which is yellow.
Jennifer Mass, head of the Scientific Research and Analysis Laboratory at Winterthur museum in Delaware, said that Le Bonheur de vivre, a famous series of paintings by Henri Matisse, are deteriorating rapidly. One version, at the Museum of Modern Art in San Francisco, is almost unrecognizable, while another version at the Barnes Collection in Philadelphia is closer to what Matisse painted. Again, the culprit was cadmium sulfide.
Cadmium sulfide is not a long-lasting pigment. It starts on the artists’ palette as yellow and, over years, fades to white.
Mass said it is a warning to the conservators in San Francisco to do something.
The same thing is happening to the four versions of Edvard Munch’s painting of existential angst, The Scream, one of which sold for $120 million in 2012. Much of the background involved Munch’s use of cadmium sulfide yellow and it is turning white rapidly, Mass said. Because how extensively Munch used it in The Scream, much of the work could be gone in another 50 years.
Paintings also change color. The most famous example hangs on the walls of the Art Institute of Chicago, Georges Seurat’s Sunday Afternoon on the Island of La Grande Jatte, painted in 1884. Clearly this is serious because artists chose colors deliberately.
The painting shows a group of people standing or sitting about on an island on the Seine River near Paris. Seurat spent two years working on it, including time on the island. He used a technique called pointillism, in which the images are constructed using thousands of dots. Color and tone were changed by changing the color of the individual dots. He used zinc yellow for the lawn and mixed that paint into other shades.
The zinc yellow started turning brown almost as soon as he applied it, according to Francesca Casadio, director of the science lab at the art institute. Fifty years later, the lawn was simply a different color, something like a writer’s words changing while sitting in a book.
Casadio said no one knows if Seurat knew this was going to happen. Insights from today's chemists and preservationists can help explain what happens to paintings, but not what the artist was thinking.
Joel Shurkin is a freelance writer based in Baltimore. He is the author of nine books on science and the history of science, and has taught science journalism at Stanford University, UC Santa Cruz and the University of Alaska Fairbanks. He tweets at@shurkin.