Figuring out what killed crazy Caravaggio
Jun24

Figuring out what killed crazy Caravaggio

“Caravaggio’s life was even darker than his paintings.” This is how Italian microbiologist Giuseppe Cornaglia began an account of his uphill battle to figure out what microbial pathogen may have killed the famous and violent 16th and 17th century Italian painter, who died under rather curious circumstances in 1610. Cornaglia is part of a growing number of researchers who look into the dental pulp of skulls found in graves, in search of DNA from ancient pandemics. The field is called paleomicrobiology, and it’s been used to figure out what microbes caused the Plague of Athens, which indirectly helped Sparta topple Athens in the Peloponnesian War, and which in turn instigated the decline of classical Greece. Paleomicrobiology has also been used to show that tuberculosis was already in the New World before Columbus showed up carrying a host of other deadly pathogens on board. So, given that Caravaggio died under strange circumstances (more on that in a second), Cornaglia wanted to look at Caravaggio’s remains and see if he could detect the presence of a deadly pathogen in the artist’s dental pulp. Dental pulp harbors the DNA of microbes present in the person at death. The pulp tissue is covered by protective enamel so that contamination from other microbes can’t occur during the intervening centuries, before forensic researchers dig up the skeleton and crack open the tooth. The first problem Cornaglia faced was that he didn’t know where Caravaggio’s remains could be found. This is not entirely surprising when you learn more about the painter. Caravaggio was an angry guy and quick to pull out his sword. During a fight in 1606, at age 35, he tried to castrate his opponent during a street brawl in Rome, Cornaglia said. The castration was successful. But it also killed Caravaggio’s foe, leaving Caravaggio with a murder charge and a life on the run. The experience didn’t reign in Caravaggio’s predilection for violent fights. According to Cornaglia: “The artist’s last years were spent desperately running from one city to another. After stopping by Naples, he travelled to Malta, only to get into trouble after yet another brawl. Caravaggio was imprisoned by the Knights in August 1608 and later expelled from the Order “as a foul and rotten member.”… After some time spent in Sicily, unknown assailants attempted to murder Caravaggio in Naples, succeeding in disfiguring his face… Contemporaries described the artist as a madman during this time, exhibiting increasingly strange behavior and exploding into a violent rage at the slightest provocation.” Digression: some researchers have wondered if Caravaggio’s inherent aggression was being exacerbated by lead poisoning, as the dude actually ATE off of...

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Was antiquity really so tacky?
May20

Was antiquity really so tacky?

The ancient Greeks did it, and now the Phoenicians too. Over the past few years, it’s become increasingly clear that many of the white marble statues from Greece’s golden era were originally painted in garish colors. The discovery of pigment residues on a multitude of classical era sculpture has been a boon for lovers of kitsch and a downer for pretty much everybody else. Yeah yeah, I know it’s good to know The Truth, and it is fascinating that they had such bad taste but, well… Sigh. So it turns out that the Phoenicians, an ancient Semitic seafaring civilization who traveled around the Mediterranean from about 1500 BC to 300 BC, also painted and gilded their carvings. The Phoenicians invented an alphabet later adopted by the Greeks. One wonders if the Greeks also got their predilection for painting sculptures from the Phoenicians? A team of French and German researchers analyzed the surface of several Phoenician ivory sculptures held at the Badisches Landesmuseum Karlsruhe, in Germany, and found metal traces corresponding to ancient pigments and (gold) gilding. These metal traces are invisible to the naked eye, but can be detected using a technique called X-ray fluorescence. Ina Reich, the lead researcher of the Analytical Chemistry paper reporting the discovery, says she’s also found the same type of metal residues on Phoenician pieces at the Louvre–work which will be published elsewhere in the future. (I wrote a more science-y news article on the discovery here.) For the lovers of nanoscience out there, here’s a teaser: Reich also mentioned that some of the traces of leftover gold from Phoenician gilding had formed curious gold nanoparticles on the surface of the ivory after spending centuries underground. Reich is currently analyzing the gold nanoparticles, which she says would be impossible for forgers to emulate and thus may be a new cool new way to authenticate Phoenician...

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When a Rembrandt copy is not a forgery
Jan25

When a Rembrandt copy is not a forgery

So you’d think that making a replica of a Rembrandt might be frowned upon by the art world, but this copy of “An old man in military costume” has full approval of its owners. In fact, the folks at the Paul Getty Museum in LA, asked their own intern to replicate the masterpiece as well as the hidden painting beneath it. It seems that there’s a pretty good reason for making the copy, or “mock-up” as the researchers call it. For years, museum researchers have known that there’s another painting beneath the military portrait. But they’ve had a tough time getting more than just a faint whiff of the image hidden below using standard analytical methods. Over the past few years, a new technique called scanning macro X-ray fluorescence (MA-XRF) has proven itself useful for uncovering hidden paintings on canvases by Van Gogh, Goya and others. The question is whether MA-XRF would work for Rembrandt’s military portrait. And specifically, whether a portable X-ray device was powerful enough to do the trick or whether the painting should travel to a more a powerful synchrotron X-ray source, such as in Hamburg (DESY) or at Brookhaven National Labs in New York. It comes down to the fact that museums don’t like shipping valuable and fragile art around the world unless it’s absolutely necessary. Enter intern Andrea Sartorius (who I momentarily hoped was a descendent of the 17th century Croatian weight-loss fanatic & innovator, Sanctorius Sanctorius. Sadly the names are not quite the same.) Anyway, Sartorius painted a copy of the original Rembrandt using the same kind of pigments and binder that he would have used, and she included another portrait below the military one. Then the copy was shipped around the world to be analyzed using X-rays from the various synchrotron sources and from the portable device. Turns out it’s worth the trip to more snazzy X-ray sources if you want to see the hidden painting below. The team argues in this paper that transporting the Rembrandt to a synchrotron facility is actually “useful and relevant.” The paper’s lead researcher, Matthias Alfred, praised the mock-up: “It is the first time that a painting was reproduced in such an elaborate way for these tests.” It seems that experiments on mock-ups help museum staff decide whether sending expensive art to outside labs for analysis is worth the risk and effort. And that, my friends, is how a fake Rembrandt can sometimes be a good...

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Dirty Dishes: Fatty residues on pottery fragments point to 6000 B.C. cheese-making
Dec12

Dirty Dishes: Fatty residues on pottery fragments point to 6000 B.C. cheese-making

Nearly eight thousand years ago in an area that is now called Poland, a prehistoric person skipped dish-duty. Thanks to this delinquency, researchers in Poland and the UK led by Richard Evershed have been able to analyze the dirty residues on these dishes. Today the scientists report in Nature that the fatty acid leftovers are Northern Europe’s earliest evidence for cheese-making. And tomorrow, teenagers everywhere will begin arguing that dirty dishes buried under beds are a gift to future archeologists. But seriously, archeologists are interested in the onset of cheese-making for several reasons. First, because cheese-making permitted humans to gain protein nutrients from domesticated livestock year-round, and without killing the valuable animals. Second, cheese has less lactose than straight milk. So the development of cheese-making may have been a way for lactose-intolerant prehistoric humans in Northern Europe to gain nutrients from something that would otherwise make them extremely sick. Finally, “the production of cheese is a technically complex process,” note the authors. Thus the knowhow shows some advanced food science skills. To make cheese you first have to coagulate milk with acid or enzymes, so that you get semi-solid cheese curds. Then you have to separate the curds for the liquid whey. The pottery fragments analyzed in this study were pierced with holes, and were liked used as a sieve to separate the curds from whey. Other research by the same scientists on vessels from Anatolia, in Turkey, have pointed to cheese-making as far back as the seventh millennium, older than the Northern Europeans. This not the only time that researchers have discovered interesting residues on ancient vessels. In January, scientists at the Library of Congress found traces of nicotine at the bottom of a 700 A.D. Mayan pot, the first physical evidence of tobacco use by this civilization. And in 2010, traces of body paint pigments were found in 50,000-year-old shells on the Iberian Peninsula, evidence that even Neanderthals liked to pretty themselves up before a night out on the...

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The military borrows from cultural heritage science.
Nov07

The military borrows from cultural heritage science.

Civilian society constantly makes use of aerospace and military inventions: Can anyone say the Internet? Or transparent braces? (These nearly invisible dental devices are made from a material called polycrystalline alumina, which was initially developed by NASA “to protect the infrared antennae of heat-seeking missile trackers,” notes Discovery.com) Cultural heritage also borrows from NASA: Portable X-ray fluorescence spectroscopy (XRF) was developed for MARS missions, so that roaming rovers could assess the chemical make-up of rocks on that planet. Now XRF is a must-have tool for conservation scientists, who want to analyze the chemical composition of art that cannot be transported into a lab, such as a cave painting or Renaissance fresco. But what about reversing the direction of technology export, so that cultural heritage scientists return the favor by developing new analytical tools for art research that then get delivered to the greater world of science? This has not happened—until now*. (*Or so I think, after asking folks in the know… If I’ve missed an example, I trust the Internet’s dilligent fact-checkers to clarify.) Anyway: As far as I know, the first case of analytical technology export from a museum lab to the outside world of science comes courtesy of John Delaney, who works at the National Gallery of Art in Washington. Delaney has long been working in the field of near infrared imaging spectroscopy (NIRS), sometimes with the army’s Night Vision Lab. NIRS is versatile analytical tool that can be installed on satellites for remote sensing of ground soil chemistry. Or it can be put in a medical device to measure a patient’s blood oxygen and hemoglobin levels through their skin, non-invasively. One of the coolest applications of NIRS in cultural heritage science is to visualize paintings made below other paintings, such as the hidden portrait of a beautiful woman below Picasso’s Le Gourmet, which is a still-life of a child eating. Delaney’s project to uncover another hidden Picasso painting was very recently profiled in the New York Times. Earlier this year, Delaney published an article in Angewandte Chemie wherein he used NIRS imaging equipment from the US military’s Night Vision lab to study binders and pigments in a 15th century illuminated manuscript by Lorenzo Monaco, called Praying Prophet. Too much incident light can hurt the ancient, fragile document, so Delaney had to use the lowest possible light power settings, filter that light, and effectively work at the sensitivity limits of the NIRS instruments. As part of the project his team improved the sensitivity of two cameras used to analyze the manuscript. Delaney says that the new cameras which operate at low light levels have now also been used on paintings and tapestries to map wool and...

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Weeping Paintings
Oct15

Weeping Paintings

You don’t really expect a seemingly dry painting to suddenly start oozing streaks of wet paint, seven years after its completion. So when Otto Piene’s Harvest, which was finished in 1993, began to weep white paint in 2000, owners, conservators and the artist were all rather surprised. Although Harvest is Piene’s only work to start weeping, the strange liquefying process has happened to dozens of other artworks from contemporary artists as varied as Jonathan Meese and Frank von Hemert, explains Jenny Schulz, a conservator in Cologne, Germany, who’s made it her business to figure out why. “It’s quite a common thing,” she says. Taking a closer look at several of these paintings, Schulz figured out something that all the weeping paintings had in common: The tears occurred in places on the canvas where the artist has laid down a thick layer of oil paint. Although the thickly-laid paint seems to dry, it turns out to be unstable and capable of liquefying. But why? It’s not as if applying thick layers of oil paint is a new thing among artists… Yet the weeping painting issue is relatively new, having emerged in the last two decades or so. What’s changed, Schulz says, is formulation of oil paints. Until recently oil paint was made using linseed oil. But the problem with linseed, she says, is that it has a tendency to yellow over time. So paint formulators began exchanging linseed oil for sunflower oil, because sunflower oil doesn’t yellow. The problem is that sunflower oil doesn’t dry as well. That’s because the oil contains fewer reactive double bonds, which are required to form a permanently dried paint complex, Schulz says. Thick layers of the sunflower oil paint may seem to dry, but they are unstable. Subjected to changes in temperature and humidity or even the jostling that occurs during transport, these layers can collapse, releasing component parts as a gooey tear running as fast as 2 centimeters per month. Other paint components can help or hinder the instability, Schulz says. For example, formulators have been increasingly replacing lead-based pigments for titanium- or zinc-based ones in white paint. Unfortunately, lead seems to help paintings stay stable, while replacements are not as effective. Additional ingredients in oil paints such as bees wax  (used to stabilize pigments) and aluminum stearate (used to improve viscosity) may also play a role in the ability of sunflower-oil paint to dry completely, Schulz adds. She’s currently developing recommendations for formulators and artists on ways to avoid the weeping painting problem—and she’s also working on strategies for conservators tasked with stopping the flow. As an aside, paintings aren’t the only cultural artifact to shed tears: Plastic...

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