Peasant head, a painting from an earlier period in Vincent van Gogh’s career, depicts a woman from a town in the southern Netherlands. It was here – where Van Gogh lived from 1883 to 1885 – that he painstakingly immortalized his facial features and simple clothing in oil paintings.
But on the reverse of the work, hidden behind layers of glue and cardboard, is another painting: a bearded man with a wide-brimmed hat and a loose handkerchief. His gaze is unbending and although the right side of his face is in shadow, his left ear is clearly visible.
Art curators at the National Galleries of Scotland discovered the mysterious image in July using X-rays, as part of a routine examination. They speculate that Van Gogh, who often repurposed his canvases to save money, created the work after Peasant head; instead of painting over earlier works, like some painters, he turned the canvas over and worked on the back. IThis is probably the oldest known self-portrait by the Impressionist artist.
“[This is] an astonishing – potentially truly revolutionary – discovery, because now a whole generation of art historians will have to figure out how this new self-portrait fits into the canon,” says Francesca Casadiofounder of the scientific research laboratory of the Art Institute of Chicago who was not involved in the work.
Art historians and restorers have used X-rays in this way for almost as long as we know of them, she adds. In fact, this scientific approach to the study of works of art has been well established in museums and universities since around the late 19th and early 20th centuries.
Senior Curator Lesley Stevenson looks at Head of a Peasant Woman next to an x-ray image of Van Gogh’s hidden self-portrait. (Credit: Neil Hanna)
“Scientists like me use the tools of science to interrogate materials, and those materials turn out to be works of art,” says Casadio. “The best way we can engage with humanities professionals or curators and curators is with these scientific techniques that produce images; because then we have a common language.
Explore the paintings
In the world of art conservation, paintings can be x-rayed for a variety of reasons. As in the case of Peasant head, for example, such analyzes can take place before exposure. If conservators are preparing a painting for treatment and there are questions regarding its structural integrity, it may also be x-rayed. And sometimes, when a museum acquires a work of art, the seller may allow this type of non-invasive investigation.
Read more: How Science Saves Van Gogh’s Flowers Before They’re Gone
Non-invasive is the key word here. “There is always radiation that the painting is exposed to,” says Casadio. “However, it’s not of an intensity that can cause significant changes to the materials themselves.”
There are other non-invasive interrogation methods that scientists like Casadio use, including X-ray fluorescence, ultraviolet light, and infrared light. Basically, these different wavelengths across the electromagnetic spectrum penetrate different depths of a painting. The researchers then use these methods in a complementary way.
X-rays are excellent for imaging dense or heavy materials. This is why they have a habit of looking inside the human body when something is wrong: dense bones and even tumors absorb much more radiation than soft tissues, and therefore appear white. X-rays also pass through the entire paint, from the top varnish to the back of the canvas. During this time, the ultraviolet or UV light stops on the surface of the paint. But it can be a very powerful tool for identifying areas that need restoration, Casadio says.
Like X-rays, infrared waves penetrate both layers of varnish and paint, but anything containing carbon – including the charcoal or graphite that artists have used to sketch out a composition – will absorb them. . This means, Casadio explains, that researchers can scan a painting in infrared if they want to reveal underdrawings.
In some areas, art historians have been able to distinguish one art school or studio from another based solely on an infrared image and the quality of these underdrawings. “Or, if you look at the panel paintings in the churches, you sometimes see the master writing notes for the assistants in the studio,” she adds.
Then there’s X-ray fluorescence, which isn’t used to just take an image. It records the reactions that the atoms (especially their electrons) of a material have when exposed to X-radiation; because each element emits a different fluorescence, this allows researchers to identify the chemical constituents of a material. This, combined with art historians’ knowledge of pigments and how paint is made, says a lot about a work of art and the artist who created it.
A colorful collaboration
There are of course still limitations to these approaches. On the one hand, says Casadio, researchers are limited in their ability to image organic matter in an information-rich way. This becomes a problem when trying to characterize the different binders that artists used to adhere their pigments to a surface – oil, glue, even egg.
“In the 19th and 20th centuries, some artists used mixtures of [these] materials because they were really interested in surface and textural effects,” she says. “We are very limited in how we can characterize them.”
Yet this type of work reveals new knowledge every day, which is then transmitted to scientists and humanists for interpretation. Casadio, who has in the past studied Van Gogh Bedroom at the Art Institute of Chicago, appreciates the multidisciplinary aspect of this collaboration. “Maybe a person doesn’t care about Van Gogh, but thinks it’s cool to peel off the layer under a painting,” she says. “It’s a way to reach people where they are.”
She speculates that researchers at the National Galleries of Scotland will attempt to scan the newly discovered Van Gogh using X-ray fluorescence to understand some of his colors. It may also be possible to physically discover the hidden self-portrait. Although the process of removing all that glue and cardboard, which experts say was added for structural integrity in 1905 when Peasant head was loaned to a major exhibition in Amsterdam, will require delicate hands.
Back of the head of a peasant woman. (Credit: Neil Hanna)
“I mean, every time you handle a piece of art, there’s a potential risk. But it’s also true when you hang the painting for public enjoyment, when you put it in the galleries so activists can to stick [to it]“says Casadio.
Yet these types of unexpected discoveries have already been made. In 1929, Dutch restorer Jan Cornelis Traas removed the cardboard from three paintings from the Van Gogh Museum in the Netherlands, revealing the portraits on the reverse.
Either way, the latest find will be on display in Edinburgh this summer, from July 30, the National Galleries of Scotland announced in a press release. Visitors will be able to see the X-ray image for themselves for the first time, thanks to a specially designed light box in the center of the screen.
“And the more we can see,” Casadio notes, “the more we will want to see.”