Rare Aztec Document Gets A Check-Up

In 1521, the Aztec capital of Tenochtitlan fell to the Spanish invaders, who burned libraries and destroyed most of the manuscripts pertaining to Aztec history, religious rituals and economy. The Codex Fejérváry-Mayer is one of just two dozen or so Aztec texts to survive the Spanish invasion. It’s also just one of just six screenfold books that were penned before Cortez started his conquest of Mexico’s indigenous people. So suffice to say that it’s a pretty exceptional record of the pre-Spanish Mesoamerican world. This codex is called a screenfold book because Aztec scholars would literally twist and fold the 22-page, double-sided document to cross-reference a particular date to two calendar cycles: the yearly cycle of 365 days and the sacred cycle of 260 days (called tonalpohualli). Joanna Ostapkowicz, a curator at the World Museum in Liverpool, which hosts Codex Fejérváry-Mayer, explains it in this way: “In the hands of ritual practitioners and other high-ranking individuals, the codex became a guide for people’s actions. The screenfold’s internal reading structure is right to left and is determined by the number-and-sign sets of the calendar: how the images and symbols cross-referenced each other was then interpreted by the reader, who was well versed in the significance of the various icons. Although an object of great respect, the codex was also a tactile, malleable reference tool: a user could consult both sides simultaneously by folding parts of the codex onto itself. Reading it offered guidance on appropriate days to travel, to celebrate a deity’s beneficence with sacrifices, to plant crops or to name a child.” These days the codex is not twisted and folded as it once was. In fact, it doesn’t get handled much at all due to the animal-skin document’s fragility and worth. When Mesoamerican experts want to study the codex, they typically have to rely on photographs, Ostapkowicz notes. A very rare exception was made a few weeks ago when MOLAB, a nomadic team of conservation scientists from Italy, drove up to Liverpool to help museum staff study the pigments, dyes and binders used to make the codex. The MOLAB team has a battery of snazzy equipment that can study fragile artwork without taking a sample of it—in the same way that an X-ray, ultrasound or MRI can give doctors insight about what’s going on inside a patient without invasive surgery or removal of a blood sample. In the case of the codex, the analytical equipment used by the scientists relies on X-rays and infrared light to diagnose the document’s inner make-up. I’m really looking forward to what the researchers find, once all the data is analyzed. As Ostapkowicz puts it,...

Read More

Arsenic Contamination Of Artifacts

A few weeks ago I got to touch the hairy underbelly of an armadillo. Even though it hadn’t been alive for some time, I was still pretty chuffed about the whole experience—I mean, it’s unlikely I’ll ever have such an intimate moment with an armadillo again. The beast in question had been briefly removed from its basement cupboard home at the North Carolina Museum of Natural Sciences as part of a behind-the-scenes tour during the recent Science Online conference. The experience of handling a stuffed armadillo was not just exceptional because it’s a stuffed armadillo. The experience was exceptional because it’s rather unwise to spontaneously handle animal or plant-based artifacts found in museum storage rooms. Until the 1970s, many biologically-based artifacts were doused with arsenic (as well as lead, mercury and some organic pesticides such as DDT) to keep insect and microbial invaders at bay, explained Lisa Gatens, the NCMNS curator of mammals who let me and others on the tour touch the animal. (For the record, the armadillo was safe.) Since the practice of adding pesticides to biologically-based artifacts began in the 1800s, there are an awful lot of contaminated museum artifacts out there. And many have levels of arsenic that could pose a problem to human health if handled without protection. A quick Internet search brought me to Nancy Odegaard, a conservator at the Arizona State Museum, who has spent a huge chunk of her career trying to come up with solutions to this contamination problem. Odegaard told me that concerns about contaminated artifacts initially arose in the 70s and 80s, during that era’s increasing awareness about the dark side of some commonly used chemicals. The museum community began to worry that conservators and curators working with artifacts might be at risk, not to mention museum goers participating in hands-on exhibits. Then in 1990, the US government launched the Native American Graves Protection and Repatriation Act. At this point, museums began returning artifacts to Native Americans who might start using the pieces in ceremonies instead of storing them behind glass. Since many of these artifacts were made of leather, feathers and other biologically-sourced materials, they too had been subject to toxic anti-pest measures. The potential health risk to Native Americans was very concerning. “I lost sleep thinking about this,” Odegaard says. “In particular, you worry about head-dresses, which are worn near the eyes, nose and mouth–this is ground zero for contamination entry.” Odegaard started organizing seminars and conferences with Native American leaders, conservators and medical researchers to discuss contamination and how to assess health risks. (She is an author on this 2000 JAMA letter entitled Arsenic Contamination...

Read More

Bringing A Controversial Mural in LA Back To Life

In 1932, David Alfaro Siqueiros got kicked out of Mexico for his political leanings so the artist spent six months in Los Angeles, California, where he produced a controversial mural called América Tropical. Siqueiros may not be as well-known as his teacher and contemporary Diego Rivera, but these two, along with José Orozco, formed “Los Tres Grandes,” the big three Mexican muralists of the early 20th century. During his stint in LA, Siqueiros was asked to paint a mural on a second story wall that overlooked Olvera Street, which was–and still is–a romanticized, somewhat kitschy Mexican market set up for tourists. The idea was for Siqueiros to produce something that celebrated tropical America. The expectation was probably that it might be a romanticized vision of Mexico—just like the street below. Instead Siqueiros, who was a die-hard Communist, produced a profoundly political piece of art: A crucified indigenous Mexican is at the forefront of the mural, with an American Eagle flying ominously above. A sharp shooter approaches from the right with his gun aimed at the Eagle. To say the piece made a splash is a pretty major understatement. Some praised the artwork for the potency of its political and social statement. But city officials were not impressed and they pushed successfully for the mural to be whitewashed, explains Leslie Rainer, a senior project officer at the Getty Conservation Institute who is leading the mural’s conservation, and who gave me and a few others a tour of the mural’s site in downtown LA. Since the site is under construction, the mural was covered for protection, as you can see in the photo below. The site will hopefully be reopened for public viewing in the next year or two—fingers crossed. (The $8.95 million project, which is being paid for jointly by the Getty and the City of LA, has faced many delays). Many decades of outdoor exposure as well as the whitewashing took a serious toll on the artwork, Rainer says. The mural has lost all of its color, leaving just a shadow of the original piece. Conservation efforts won’t reintroduce color.  This is because there’s no color documentation of the artwork, so any addition of pigment would be a misrepresentation, explains Susan MacDonald, head of GCI Field Projects. Instead, Rainer and the GCI team have carefully cleaned off the whitewashing and reattached parts of the crumbled plaster. They’ve also been doing non-invasive analyses of the artwork, which is an unusual marriage of traditional fresco painting and cement (instead of lime plaster), Rainer says. Siqueiros was really enamored with the (new-to-him) cement and concrete materials that he encountered during his stint...

Read More

Traces Of Tobacco In Mayan Pottery

Conservation scientists went spelunking in to this Mayan pot from 700 A.D. and found traces of nicotine, the first physical evidence of tobacco use by the ancient civilization. Staff at the Library of Congress, where the pot is housed, might have been tempted to guess that tobacco was indeed inside, since the Mayan script on the container says so. But they were wiser than that. There have been many cases where the inscription outside a vessel does not match what’s inside-sometimes intentionally so, as is the case with certain Mayan rituals, the researchers note in their article, which will be imminently published in the journal Rapid Communications in Mass Spectrometry. In fact this is only the second case to-date (with Mayan artifacts) where the packaging information has accurately matched the goods. The other example dates back to 1989 when scientists found traces of cacao in a correctly-marked Mayan container from Guatemala. Researchers at Rensselaer Polytechnic Institute and the University of Albany used a technique called mass spectrometry to identify the traces of nicotine at the bottom of the pot. They were lucky that the residues had not been degraded over the past thousand years and that the pot hadn’t been stuffed with iron oxide, a commonly used burial material that would have drowned out the nicotine signal. The analytical technique they used is also helping to identify all sorts of other day-to-day products and ingredients used by ancient civilizations. Researchers at the Louvre have used mass spectrometry to help identify pink powders in ancient Greek and Roman cosmetics, as well as blood in the coating of animal artifacts from Mali–to name only two of many...

Read More

Conserving Canada’s Valuables

Canada may not be rife with Roman ruins and Rembrandt masterpieces but the country has more than enough art and artifacts—such as one-of-a-kind First Nations leather work, Group of Seven landscape masterpieces and famous hockey gear–to keep cultural heritage scientists at the Canadian Conservation Institute in Ottawa very busy. With an annual budget of $12 million (CAD) from the federal government, the CCI’s mission is to provide scientific support to some 2500 museums and 1000 archives across Canada. I was passing through Ottawa last weekend and managed to slip in a visit to the CCI headquarters, where Charlie Costain, the CCI’s director of research, conservation and scientific services took me on a great tour of the warehouse laboratories. Costain told me that one of CCI’s tasks is to scrutinize work by famous Canadian artists so that the institute can help museums with authentication, should the need arise. To do so, scientists typically look at the paint chemistry in an artist’s masterpieces to find commonalities and any unique oddities that could help fingerprint an original.   If the artist has had somewhat consistent preferences in their art supplies over time, such as the landscape artist Tom Thomson, then figuring out common chemical characteristics is possible. But this task can be seriously tough when an artist has not used consistent materials over time. This is the case of Norval Morrisseau, an amazing Aboriginal Canadian painter who was sometimes so broke he produced art with whatever paint he could find on whatever canvases he could find. Even before Morrisseau died in 2007, there were so many forgeries of his work on the market that he founded an organization to help track his authentic paintings. As Costain took me through the labs we saw projects on everything from restoring lovely indigenous birch tree baskets to gorgeous antique world globes. We also passed by a project to restore a silk flag from the War of 1812—a war that many Canadians have a not-so-secret fondness for because Canada beat the U.S. on the battlefield. (Full disclosure: I hold both Canadian and American passports.) Next year is the 200th anniversary of the victory and conservators are trying to get the gold- and brown-colored, threadbare flag into tiptop shape for display. Another great stop on the tour was with Greg Young, a conservator with a specialty in leather. He’s spent many years studying indigenous leather work and the collagen fibers that make it up. If collagen gets too wet over time, the proteins which are arranged in a triple helix can unzip and turn into mushy gelatin. Leather can also get dry and brittle in dry conditions. Young has...

Read More