How long should conservators protect David Beckham’s football?

It’s a hypothetical question, really, because Beckham has certainly owned a lot of footballs. But let’s just consider the ball that he famously kicked in 1996 from the halfway line, the one that landed spectacularly in Wimbledon’s net and helped make him famous in both the UK and abroad. So you could argue that this ball should end up in a British museum, given Beckham’s huge impact on sports culture in the UK at the turn of the 21st century. Kept under the right temperature, humidity, and light conditions, a leather object like his football could potentially last thousands of years before degrading into a mess of gelatinized protein. But really, should a museum pay the energy bills to keep his ball under optimal relative humidity, light levels and temperature so that it lasts for a millennium or two to come? Will people care about David Beckham’s ball in 50, 100, or even 500 years? What about other cultural heritage objects, such as Albert Einstein’s papers? Or a Van Gogh painting? Or an Ansel Adams photograph? In other words, long should museum or archive collections be expected to last? In principle “we’ve been working on the premise of forever. But that’s actually not realistic. Nothing lasts forever,” said Paula De Priest, deputy director of the Smithsonian’s Museum Conservation Institute. Last Thursday, De Priest and other cultural heritage researchers met in London to discuss the development of new ways to realistically assess and predict the lifetime of art and artifacts. This new field of conservation science is called collections demography and it aims to make quantitative predictions about the possible and probable lifetimes of cultural heritage objects under different storage and display conditions. The idea is to use mathematical risk algorithms to model the possible lifetimes of museum and archive collections, explained the University College London’s Matija Strlič, a collections demography researcher and the workshop’s host. As energy costs rise and cultural heritage budgets tighten, these mathematical models will hopefully allow museum and archive staff to make informed, evidence-based decisions about how best to divvy up resources or what conservation strategies will keep a collection in good condition for a particular amount of time. Strlič’s team is developing Excel-based spreadsheets that would allow museum staff to predict the possible lifetimes of museum or archive collections under various future scenarios. For example, the lifetime of a paper document will depend on the relative humidity and temperature of storage, how much light, pollution and handling the paper is subjected to, and what the paper’s pH is. If you input specific storage and display conditions of a paper collection, the software predicts what...

Read More

Nuclear Waste Signage Must Last 100,000 Years: Will the Messages Be On Sapphire Disks With Platinum Print Or Pieces Of Broken Pottery?

Humans have been around for 50,000 years and the nuclear waste we’re producing today is going to be harmful for 100,000 years. So how do we create signs that alert our descendents about enormous underground nuclear waste repositories when we don’t know what language they will speak? “A vast underground space with all sorts of curious objects inside… This sounds exactly like where future archeologists are going to want to go digging,” said Cornelius Holtorf, an archeologist at the Linnaeus University in Sweden, who spoke at a Euroscience Open Forum (ESOF) session. The session focused on how one formulates a warning message with a 100,000-year lifetime when humans have never built anything that has lasted one-tenth of that time. If we say ‘don’t dig here,’ you can bet that it will only make the site more enticing, Holtorf said. Linguists, archeologists, scientists, engineers and historians have been tackling the issue for decades. Some potential solutions sound a tad wacky: Namely the idea to create an atomic priesthood that carries on an oral tradition about the waste. Other solutions sound temptingly techie, but perhaps a tad expensive: For example, Patrick Charton from the French National Radioactive Waste Management Agency showed the ESOF audience a 25,000 € sapphire disk which could hold warning messages in platinum script. The disk satisfies the longevity criterion: It has a lifetime of at least a million years, he said. Since 40,000 pages of information can be deposited in platinum on the disk, warnings and technological specs could also be inscribed in a potpourri of languages, he added. But the sapphire-platinum solution costs a lot of money. And this is a serious down side, notes geologist Marcos Buser, who has worked with the Swiss Federal Nuclear Safety Commission in this Spiegel article. (It’s in German.) “The material cannot be valuable, otherwise it will be stolen,” said Buser. He favors putting warning messages on pottery sherds instead, since pottery has a long lifetime and broken pieces are less likely to be stolen. I can’t think of two more disparate solutions. I’m guessing something midway between the two will eventually be chosen. For example, Charton mentioned that researchers are trying to replace the expensive sapphire with cheaper, long-lasting glass. Whatever is eventually chosen, I’ll bet archeologists of the future scrutinizing the artifact-to-be will marvel about current-day humanity’s desire for energy—a desire so great that we produced waste to last 100,000...

Read More

Figuring Out Copper Corrosion To Fight Artifact Forgery

The green corrosion on copper artifacts, sculptures and buildings is so aesthetically pleasing that countless recipes exist in books and online so that do-it-yourselfers can create the same look on anything made from the metal. But depending on the recipe or the environmental conditions, that pretty green color could be any one of a handful of different corroded copper chemicals, such as nantokite (CuCl) or paratacamite (Cu2(OH)3Cl). Or, in the case of the Statue of Liberty, the green patina is a copper sulfate. Copper can also corrode into other colors besides green, such as browny-red cuprite or black tenorite. Scientists don’t actually know precisely which conditions produce the different corrosion chemicals—but they should, especially when the authenticity of an artifact is in question. For example, museum researchers need to know if the corrosion chemicals on a possibly fake copper artifact came from natural aging processes or are the result of a quick-aging forged process. To help solve this problem, Mark Graeme Dowsett, a physicist at the University of Warwick teamed up with an analytical chemist at Ghent University called Annemie Adriaens. First they started reading do-it-yourself patina manuals, such as, The Colouring, Bronzing and Patination of Metals. Then the scientists used intense X-rays to spy on the formation of one of copper’s green corrosion products, nantokite, as they made the patina according to different recipes. Among their discoveries, the team found that some steps in the recipe, such as rinsing the newly produced patina in water, produced side-products such as browny red cuprite. “Most protocols for producing the green copper patina were not developed in a systematic way,” Dowsett says. We want to figure out what’s actually going on in these different processes, he adds. Next the team is working out the conditions for making other green copper patinas, beyond nantokite. Watch out copper artifact...

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

Keeping Visitors Out To Keep Cave Paintings Safe

Guest post from Carmen Drahl, a C&EN’s Associate Editor and Haystack blogger. Growing up, I spent every summer in northern Spain, living in my grandmother’s Oviedo flat and wandering the city and surrounding villages with distant cousins. One of my greatest regrets is never having taken the 3 hour drive to what my grandma called “las Cuevas de Altamira”, the storied caves and UNESCO World Heritage Site that house some of the world’s most striking examples of Paleolithic art. The caves have been closed to visitors on and off since their discovery in the late 1870s. But they’ve been shuttered indefinitely since 2002, because microbial colonies encroached on the priceless scenes of bison and deer on the stone ceilings. Government officials in Cantabria, the Spanish autonomous community where the cave is situated, would like to reopen Altamira to tourists. Today, in a policy forum in the journal Science (DOI:10.1126/science.1206788), researchers led by Cesareo Saiz-Jimenez from the Spanish Council for Scientific Research (CSIC), argue that would be a bad idea. The team, which has been dealing with the microscopic invaders firsthand, says that letting visitors back into the cave’s fragile ecosystem would quickly undo any good that the closure has done and could cause irreparable damage. The Science piece is rich with detail about the single-celled interlopers that threaten Altamira’s cave art. They include bacteria that make food through photosynthesis, fungi, and even corn pollen blown into the cave from farms in the outside world. The presence of the corn pollen is a telltale sign that airborne fungal spores could have settled into nooks and crannies in cave walls from the outside world as well, the CSIC researchers write. The invaders come in a panoply of colors, including yellow, gray, and white, the hue that’s already besmirched some of the red pigments in the paintings. The scientists support their argument for keeping Altamira closed with an environmental study they conducted between 1997 and 1999, when the caves were still open but on a limited schedule. At the time the argument was that the small groups of 5 at a time allowed to visit would not perturb cave temperature, humidity, or carbon dioxide concentration, all factors that must be kept in check to prevent microbial flourishing. The team reports data from two consecutive days which suggest visitors have a negative impact on the cave environs. Visitors changed temperature and carbon dioxide concentration faster than the caves could bounce back. The team notes that this data comes from a day during peak tour season, when weather conditions were such that air exchange between the cave and the outside world was likely to...

Read More

Conserving Mosaics: A Nod To The Chemistry Nobel Prize

In honor of today’s Nobel Prize in chemistry to Dan Shechtman for the discovery of quasicrystals, I thought I’d write a little post on the world of mosaic art conservation. Bear with me–there is a connection. (This is precisely what I said when Paula Artal-Isbrand, a mosaics conservator at the Worcester Art Museum, answered the phone. Luckily, she didn’t deem me a random freak and then hang up.) OK. So back to the Nobel Prize. Quasicrystals are regular patterns of atoms that never repeat themselves, much “like the fascinating mosaics of the Arabic world,” noted the prize’s press release. This got me thinking–and blogger David Bradley too—because moments later he tweeted the perfect Moorish mosaic example you see here. And I knew I had to learn a bit more about mosaic art conservation and restoration. So here it goes: Tiles in mosaic art can be made of a serious potpourri of materials, such as glazed terracotta (in the case of many Moorish mosaics), as well as stone, glass, porcelain, marble, metal and wood. Compared to paintings, paper and textiles, mosaics are relatively sturdy, and not particularly susceptible to problems like light degradation, Artal-Isbrand told me. But that doesn’t make them immune to the elements, particularly because many pieces are stored outside as part of buildings. For example, freeze-thaw cycles can lead to tile and mortar cracking. Bacteria and fungi growing on the surface of these artworks can deposit ugly stains from their excretions that stay behind even after the microbes are wiped away. Worse is when there’s a crack in a tile which permits water to seep in, and thus creates a cozy home for microbes below the glaze—entirely out of reach for conservators. If the mosaic’s tiles or mortar have calcium carbonate as an ingredient (and many do), roots of plants and trees will try to extract the mineral, which is also problematic, Artal-Isbrand explained. But one of the major problems faced by mosaic conservators is the fact that there are often lose chunks at the edges of the artwork, which museum or archeological-site visitors are tempted to take home as a souvenirs. “They really need to be guarded,” she said. I asked Artal-Isbrand if conservators ever add protective coatings to mosaics. It turns out she had recently finished a project to remove unnecessary protective coatings—added decades ago—from a large Roman floor mosaic originally from Antioch which is currently housed at the Worcester Art Museum. (Roman floor mosaics are mostly made of stone, although they also used glass on occasion, Artal-Isbrand explained. That is until the Romans realized glass dissolved with time.) Back in the day (I’d guess the 1960s)...

Read More