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)...

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A Visit To The Opificio, Italy’s Primary Restoration Lab

Italy has no shortage of art, and when that art needs a face-lift, it takes a trip to the Opificio delle Pietre Dure e Laboratori di Restauro, the country’s national restoration laboratory. Located in an elegant old stable in Florence, the Opificio is like a spa for cultural heritage artifacts, where paintings, frescoes and sculptures go for age-extending treatments. When I visited, Cecilia Frosinini, an art historian and the Opificio’s director of mural paintings, was kind enough to give me a tour. As we wandered through the extensive labs, dozens of restorers were working on a wide variety of pieces including Renaissance paintings sent from Budapest for anti-aging therapy, ceramic sculptures, water-damaged frescoes and a wooden statue of Christ that had been painted to look like bronze during an era when bronze was popular but too expensive for some budgets. The Opificio has also been recently involved in everything from using ultraviolet light to bring out cool, hidden details in Giotto paintings to the restoration of Santa Croce Basilica’s famous frescoes. Like many great things in Florence, the Opificio has its root with the city’s famous Medici family. The first half the Opificio’s Italian name translates to “workshop of semi precious stones.” And as the name suggests, the Medicis founded the Opificio in 1580s to produce furniture decorated with semi precious stones, Frosinini told me. Time passed and the workshop began restoring their own pieces. By the 19th century, art made from other materials such ceramic, marble and jewelry, was also being restored, she added. The second half of the Opificio’s name, Laboratori di Restauro, refers to the restoration laboratory founded in 1932 by Ugo Procacci, who was a very important Italian art historian at the beginning of the 20th century. Around the same time that Procacci was starting a restoration lab in Florence, other museums around the world were also doing the same, such as the Fogg Art Museum in Boston and the National Gallery in London. These early restoration labs were making use of X-ray imaging–which was becoming more widespread in many fields outside medicine–to see into panel paintings and reveal what they were composed of (such as wood, metal etc). X-rays were also being used to see if there were previous paintings lying below what could be seen with the naked eye. In 1975, Italy’s newly established a Ministry for Cultural heritage decided to merge the 1932 restoration science lab and Medici’s restoration facility together and move everything into a former military horse stable. One of the major projects currently keeping Opificio restorers busy is a major restoration project of five panel paintings by Giorgio Vasari...

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Visiting The Metropolitan Museum’s Science Lab
Jun06

Visiting The Metropolitan Museum’s Science Lab

I recently passed through New York City and had the excellent opportunity to tour the laboratories beneath the Metropolitan Museum of Art with Marco Leona, who’s been the museum’s head of scientific research since 2004. “We deal with everything under the sun, that’s been under the sun for the last 5000 years or so,” he told me. The Met’s 20-person scientific team has a professional familiarity with New York’s real-estate squeeze. Their equipment is split among four labs in the Met’s Upper East Side neighborhood. Each lab corresponds to one of the museum’s four main artifact conservation departments: paintings, textiles, works-on-paper and “objects,” which is literally everything else–from metal sculptures to ceramic mosaics. Leona picked me up at the Fifth Avenue security desk on a Monday, when the museum is closed to the volumes of people who normally pack its halls. We walked unusually effortlessly through the European Sculpture and Decorative Arts exhibit to a special elevator that brought us down to the basement “objects” research space. Wandering around lab benches full of beautiful artifacts, Leona gave me an overview of the science team’s many projects. They’ve worked on everything from how acetic acid wafting off degrading ancient Egyptian wood can accelerate the corrosion of nearby metals to how researchers might use biomedical tools, such as antibodies, to study cultural heritage objects. There’s excellent logic for using antibodies: In many ancient objects, paint pigments are often suspended in paint binders that are composed of biologically-sourced materials such as egg white, plant sap, animal collagen or mixtures of all these and more. Identifying the presence of a single, specific type of biological building block, such as an egg white protein, in a complex paint mixture is really tricky. But antibodies have evolved to do exactly this. At every moment of our lives, antibodies are scouring our blood looking for specific proteins on pathogenic bacteria so that our immune system can then destroy them. It’s possible to tune antibodies to search for biological components of paint instead of naughty bacteria. Scientists in Leona’s team also develop ways to better conserve and authenticate artifacts. For example, when the Neptune Pendant, a Renaissance jewel in the Met’s collection was suspected of being a 19th century fabrication, Leona’s team came to the rescue. They dated enamel samples from all over the pendant and found that there were both 16th and 19th century components. The conclusion: the Neptune pendant was probably a Renaissance piece that got a facelift in the 19th century. (As an aside this “facelift” was likely orchestrated by Germany’s infamous art dealer Frédérick Spitzer who apparently hired artists from Cologne to Paris...

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