Category → non-invasive equipment
In the last year of Vincent van Gogh’s life, as his mental illness escalated and before his suicide in 1890, the Dutch impressionist painter voluntarily committed himself in to two French hospitals.
The isolation didn’t thwart van Gogh’s productivity–he painted some 200 paintings during the 15 months he spent in treatment. Nor did the isolation prevent him from experimenting with trendy new pigments bequeathed by the industrial revolution, such as chrome yellow, which he used to paint his famous sunflower series. This pigment fell out of favor by the 1950s when its lead and chromate make-up was found to be toxic.
Unfortunately, chrome yellow and other then-trendy pigments degrade if they are exposed to light. For example, the degradation turns the bright yellow pigment into a rather sad looking green color. Earlier this year Koen Janssens, at the University of Antwerp, in Belgium, explained the chemistry behind this degradation, by using X-ray spectroscopy to show that when the chromium in the yellow paint was subjected to too much light, it went from a hexavalent state to a trivalent state. Many media outlets reported on the discovery, including C&EN
Now Janssens has turned his attention to the so-called red lake pigments that van Gogh used in paintings during the 15 months of his life. Janssens recruited the help of MOLAB, a group of roaming scientists who travel around Europe with high tech, portable equipment. Their gear can help him study light degradation of the valuable art without harming it.
Last week, the MOLAB team, aka CHARISMA, drove 1500km from Perugia, Italy, to the Kröller-Müller Museum, in Otterlo, in the Netherlands. The Kröller-Müller has 22 paintings from van Gogh’s last months of life, and with the help of the mobile lab, the researchers can study the red pigment degradation without moving or harming the artwork.
Hopefully the new research will clarify the chemistry of the paint breakdown so that further degradation of van Gogh’s work can be avoided.
I can’t help thinking about the tragic irony of it all… that as van Gogh’s mental health was rapidly deteriorating, he was expressing himself using paint that was itself unstable.
When cultural heritage scientists go on the road, one of the most useful tools they take with them is something developed for Mars exploration: a hand-held X-ray fluorescence spectrometer. The Art Institute of Chicago’s Francesca Casadio wrote a snappy little ode to the machine, which NPR awesomely calls a “science gun.”
When researchers point the admittedly weapon-like device at a painting or a sculpture, they are able to find out which elements are present in the artwork. So for example, Casadio has used the machine to discover that about 1000 years ago, Chinese artists used a red, mercury-based paint called vermillion to decorate the lips of a female sculpture.
She also discovered that sometime in the 1800s an over-enthusiastic restorer used a zinc-based paint to give the sculpture “a new coat of lipstick,” Casadio told NPR. Hear the whole NPR piece here.
I heart the space connection. Astrochemists needed rugged and portable equipment to analyze the elemental make-up of the Martian landscape. The X-ray device also doesn’t harm whatever it is analyzing because researchers don’t need to remove a piece of the sample to do the analysis.
Instead, X-rays are directed on to the artwork or Martian rock and they either get scattered or absorbed in a way that reveals which elements are in the sample.
All these characteristics fit the bill for cultural heritage science. These researchers need sturdy, portable, non-invasive devices to study priceless art in caves, at archeological sites or even at a private collector’s home. And that’s why Casadio calls X-ray fluorescence spectrometers “the most exciting high-tech tools you’ve never heard of.”
One major motivation was time: Industrial wall paint dries in a matter of hours, while oil paint can take months. Like the rest of us, these artists had moments of procrastination. Being able to produce work just days before the opening of a new exhibit was certainly a perk, says Francesca Casadio, an organizer of the conference From Can To Canvas, and the director of conservation science at the Art Institute of Chicago.
Artists had other motivations for using Ripolin, such as shocking the stodgy traditional art world by using an industrial product, Casadio says. Some motivations were probably purely aesthetic: Industrial paint was glossier than matte oil paint. And in addition, artists could achieve unusual textures on artwork surfaces with the quick drying paint.
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Diagnosing The Devil InsideSimilar to a disease, chemical degradation often advances quietly in art and artifacts, without any external warning signals. That is, until a breaking point occurs, and museum staff are suddenly faced with a faded painting or a cracked sculpture.
Like doctors who want to diagnose patients at the early stages of their illness, when treatments are more likely to work, museum conservators also want to assess the health of cultural artifacts at the initial stages of degradation, and they want to do so non-invasively–that is, without taking a blood sample.
Now Matija Strlic at UCL has just published an article about a new diagnostic tool that can visualize the internal degradation of artifacts before the damage is apparent to the naked eye.
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Every once in a while, well-intentioned attempts to save a valuable painting or artifact from the decay of time bombs pretty badly. Consider the thousand-year-old ancient parchments that were laminated in the late 1950s or early 1960s–during that era’s love affair with plastics–in order to protect the valuable documents from the wear and tear of a long life. Four decades later, the yellowed and brittle laminate had to be painstakingly removed from Belgium’s oldest parchment, the Codex Eyckensis, as the decaying plastic began to exacerbate the injuries it had aimed to avoid.
Such hard lessons have since pushed conservators to look for easily reversible, minimally invasive ways to protect or restore cultural masterpieces—sometimes opting to shun any interventions altogether. Another possibility is to consider a digital restoration technique that offers “all the benefits of an Undo button,” says Daniel Aliaga, a computer scientist at Purdue University.
Aliaga and his Phd student Alvin Law have designed software that can project light images on to sculptures or paintings that, for example, can reveal to the viewer what the decaying masterpiece may have looked like before decades or millennia of deterioration. The projection can also boost faded colours on a painting or touch up decorative tints on a piece of pottery or a sculpture’s exterior. Turn off the projector, and the piece reappears in its current day form.