The frustrating thing about Superman is that he never lends his powers to the art history community. For decades, while art historians, conservators, museum workers and gallery owners have spent time and money getting their paintings analyzed using X-ray technology, he has had all the equipment right there in his eyes. So if you’re reading this, Mr. Kent, lend a hand, because when it comes to art, X-rays are one of the best ways of getting a look at the history beneath the surface of a painting.
Now in this post, it’s important to think of paintings as three-dimensional objects. The whole point of X-raying a painting is to get a look at its layers, from the varnish on top, right down to the stuff it’s painted on. Through X-ray analysis, conservators and art historians are given a good look at the materials present in the work. And by examining the resulting X-radiographs, conclusions can be drawn such as whether and how the painting has been conserved or repaired and how the artist approached the composition in the first place.
Invented in 1895 by Wilhelm Röntgen (1845-1923), the X-ray was used for the examination of art as early as the 1890’s. However, it was Alan Burroughs (1897-1965), an American art historian, who pioneered and standardized the practice of making “shadowgraphs” to examine paintings.
Basically, X-rays are a kind of radiation much like visible light. The difference is that X-rays have a higher frequency (move quicker) than light, allowing them to pass through paintings. The denser the substance or area of the painting, the better it collects the X-ray photons and the brighter that area shows up in the resulting X-radiograph. Usually, brighter areas on the X-ray represent a particularly dense pigments — lead white, for example, is extremely dense and tends shows up well, as does minium (red lead).
Also, in many paintings, brighter areas show where an additional paint layer has covered an earlier one. In such cases, it’s possible to see where the artist has changed the image from the original composition, and gives us a bit of insight into how he or she thought about the work as it progressed. X-radiographs can also help indicate whether a painting has been damaged, restored or altered by later generations of artists.
But how, specifically, can X-radiographs help us? What can they tell us? Here are some examples:
The Leonardo Lookalike: La Belle Ferronniére (c. 1490-1496)
In the late 1920’s, a Kansas City society lady took a businessman to court over a beautiful woman. It was no affair of the heart though — instead, the trial of La Belle Ferroniere was the first major use of X-ray technology to authenticate a painting. Sometimes attributed to Leonardo da Vinci (1452-1519), the most well known version of the Ferroniere hangs in the Louvre. However, in 1929 Mrs. Andre Hahn claimed that a different version — which she owned — was the authentic one. When Joseph Duveen (1869-1939), an art dealer, refuted the claim, she sued him.
In the trial that ensued, X-radiographs were used as evidence to show that the Louvre picture was, in fact, the original. Corrections to the composition showed up on the X-ray of the original image that would not be present in a copy. In other words, the Louvre’s version showed evidence of the artist thinking about and correcting the composition in the way Mrs. Hahn’s version did not. Eventually, the trial had to be thrown out when the jury was unable to reach a verdict. Nevertheless, from the art historian’s point of view, X-rays had been established as a valid form of art historical evidence.
A Rembrandt Recovered: An Old Man in Military Costume (1630-31)
X-ray technology has developed and improved immensely since the Hahn/Duveen trial. One of the most recent uses of X-radiographs has been in the analysis of Rembrandt van Rijn’s (1606-1669) Man in Military Costume.
Behind the visible figure of the old man is the image of a younger man in a simple garment. By targeting different pigments in a series of sessions, the research team at the Getty Institute has been able to rebuild a tantalizing image of this lost Rembrandt — though we may never know for sure the identity of the anonymous sitter.
Catholic Cover Up? Portrait of Sir Henry Walsingham (1704)
Sir Henry Walshingham (c. 1532-1590) was the head of the secret service under Queen Elizabeth I. A member of the Protestant Church of England, one of his primary duties was to find out groups of Catholic conspirators. However, The National Portrait Gallery’s recent analysis of his portrait shows that it was painted over a devotional image of a Madonna and Child.
While it may not have surprised any Tudor portrait-sitter to know that a canvas had been reused, images of the Virgin were strictly Catholic. So was it simply a rushed artist trying to get a portrait done with the means available? Or is it the artist’s secret joke on the Protestant policeman?
Picasso’s Pigments: The Old Guitarist (1903) and others
In 2012, a study carried out at the Art Institute of Chicago revealed that Pablo Picasso’s Old Guitarist concealed another painting. Hidden behind the old man was a woman with a child and various animals. However, the “Picasso CSI” team that worked on the project also revealed that Picasso had switched from using oil paint to off-the-shelf house paints. Some art historians had already suspected Picasso’s shift to house paint corresponded with a general change in style. And the results of the study have provided evidence that the artist used Ripolin to effect bold, glossy works in paint that concealed brushstrokes. In their research, scientists compared Picasso’s pigments with old paint samples bought off eBay, and used an instrument called the hard X-ray nanoprobe.
Whether used for authentication or analysis, X-rays can tell us fascinating secrets behind paintings. And while these might not always be essential to know, they help present a broader picture of how these beautiful objects came to look as they do today. What an amazing — scientific — superpower.
Enjoyed this post? Check out the other entries in my ART AND SCIENCE series by following the links below: