Art conservation that does more harm than good

Hindsight is 20-20, as they say. This week Art Daily* reported that a widespread preservation treatment, developed to help canvases survive humid environments, actually makes paintings more vulnerable when humidity levels soar.** “The wax-resin treatment was enormously popular in Europe and the U.S. during the 1950s and 1960s,” says Cecil Krarup Andersen at the Royal Danish Academy of Fine Arts, who made the discovery. “Many masterpieces, such as Rembrandts and Van Goghs were preventatively treated with wax-resin linings to help protect the artwork from humidity degradation. The treatment does exactly the opposite.” Anderson has just wrapped up her PhD work on the topic, a research project that began because museum staff at Statens Museum for Kunst were trying to figure out why Danish Golden Age paintings treated with wax-resin were not resisting the insults of time as well as they should. I needed a little background on wax-resin treatment which Andersen kindly provided: It was popularized in the 1800s by a Dutch restorer named Nicolaas Hopman. One of the first masterpieces to be treated was Rembrandt’s Night Watch in 1851. The overall motivation was logical: Hopman thought that coating the back of a canvas with beeswax and an extra layer of canvas would act as a protective support for the painting. Later on, he and others began mixing tree resin in with the wax because it added stiffness. Throughout the 20th century, the treatment gained popularity. Until the 1970s. That’s when conservators started talking about the importance of reversibility, the idea that any conservation treatment on artwork should ideally have an undo button, just in case a treatment turned out to have unforeseen, negative, long-term impacts or in case a better treatment came along sometime in the future. At a conference in Greenwich, England, in 1974, a group of high profile conservators decided that wax-resin treatments were not reversible and should be discontinued, Andersen says. Wax-resin treatments were gradually phased out, but it was too late for thousands of masterpieces that had already faced the hot iron. Initially conservators used irons to melt the wax-resin on to the back of paintings, upon which they adhered the extra canvas layer. Then in the 1950s, specialized heating tables were invented. These tables could uniformly heat the wax-resin and seal the back lining to the painting “in no time,” Andersen says. They made it easy for conservators to overdo it, she says. (As an aside, Andersen says the treatment additionally flattened out the texture in some paintings.) Another reason 1970s conservators became nonplussed with wax-resin was that the treatment actually changed the color of paintings. Sometimes the hot wax and resin would...

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Dead Sea Scrolls – Scientists In Berlin Criticize Israeli Cultural Authorities For Treatment Of Sacred Documents

Last week, a peer-reviewed journal called the Restaurator published a controversial article about the Dead Sea Scrolls written by two Berlin-based scientists who charge that these sacred documents are not receiving proper care from the Israeli cultural institutions responsible for their well-being. The article’s abstract does not mince words: “Examination of the properties of the scrolls proves that frequent travel, exhibitions and the associated handling induce collagen deterioration that is covered up by the absence of a proper monitoring program.” “I want the scrolls to be protected,” says Ira Rabin, who co-authored the piece entitled “Dead Sea Scrolls Exhibitions Around The World: Reasons For Concern” with her colleague Oliver Hahn at the German Federal Institute for Materials Research and Testing. The 20-page document specifically criticizes the Israel Antiquities Authority and the Israel Museum in Jerusalem, who hold responsibility for a majority of the Dead Sea Scrolls. Both defend their treatment of the scrolls (detailed below). But first, the criticisms. Rabin and Hahn argue in the Restaurator that: 1. The Dead Sea Scrolls are being exhibited far too much, and that the consequent travel and handling is seriously accelerating their degradation. The authors show that there’s been a substantial increase in international exhibitions in the past two decades.                             2. No scientifically sophisticated system is yet in place to monitor the degradation state of the Dead Sea Scrolls. The authors argue that all exhibitions should be stopped until a rigorous analytical monitoring system is established and can prove that the frequent traveling is not unduly exacerbating the fragile state of these documents. 3. Current strategies to conserve the scrolls may, in some cases, be worsening their state. In particular the authors take issue with the reinforcement of the scrolls with Japanese tissue paper. This process requires the use of an adhesive called methyl cellulose. Rabin and Hahn argue that use of the adhesive brings the scrolls in contact with unnecessary moisture. They say this wetness is causing collagen in the animal skin parchment to unravel irreversibly from its triple helix formation into an amorphous gelatin. They include an image of this gelatinization to make their point. The article’s first author, Rabin, worked as a consultant at the Israel Antiquities Authority (IAA) from 2005-2006. From multiple accounts, Rabin and the IAA did not part on congenial terms. In 2007, Rabin received a letter from the IAA’s lawyers (seen by Artful Science) threatening legal action if she presented work from her time at the IAA at a conference or in a publication, based on an employment contract she had...

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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...

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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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The Peculiar Life Of The Dead Sea Scrolls

After spending more than two thousand years in peaceful hibernation, the Dead Sea Scrolls (DSS) have had a rough six decades. Discovered in several dry caves near the Dead Sea from 1947 through 1956, the texts experienced a series of travel and conservation adventures that border on mishandling, says Ira Rabin, a staff scientist at Germany’s Federal Institute for Materials Research and Testing (BAM). Rabin has published several scientific papers on the Dead Sea Scrolls, which have historical and religious importance because they contain early versions of the Judeo-Christian Old Testament as well as other important Jewish writings. I recently met Rabin at a cafe in Berlin, where she described to me the potpourri of treatments that these texts—most of which are written on animal skin parchment–have received since their discovery. The Dead Sea Scrolls have been covered in castor oil and glycerin as well as plastic consolidants (the latter of which is particularly unwise because no plastic stays in good shape for more than a few decades). Other treatments include Fuller’s Earth, a clay-like material, and being attached to glass plates using adhesive tape. On the plus side, last year, some of the Dead Sea Scrolls were digitized for online viewing by the Israel Antiquities Authority (IAA). But from her analytical studies of the scrolls and from her former role as scientific advisor with the IAA, Rabin told me she is generally worried that the scrolls are being exhibited too much around the world. By her count, some of the scrolls are on display for over 200 days in a year. Rabin is concerned that the handling and exposure to light, humidity and traveling is accelerating the degradation of these texts. Besides providing an analytical assessment of the scrolls’ degradation status, Rabin says that science can also help answer historical questions that remain hotly disputed by scholars. Researchers still don’t know, for example, where and how the scrolls were produced. To answer the “where” question, Rabin and colleagues evaluated the ratio of bromine and chlorine in a collection Dead Sea Scrolls, and published the newest results in July. (I previously wrote about the technique’s proof-of-principle.) Bromine and chlorine are both found in sea water. These chemical species enter the animal parchment during an ancient processing step wherein the animal skins are soaked in sea water. Since the bromine to chlorine ratio varies in different water at different locations, the researchers posited that the ratio can be used as a geographic fingerprint. Using this theory, Rabin and colleagues report that some of the parchments were indeed processed in Dead Sea water and thus were produced near where they were...

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Plastics Denial Syndrome

Sometime during the 1960s, artists en masse began using plastics to make art–a trend that continues today. The problem is that many plastic polymers have a shelf life of just a decade or so, after which they begin to crumble or crack. Consider an old rubber band or a plastic bottle left out in the sun. And just as bisphenol A leaches out of baby bottles and into the surrounding liquid, many of the components of plastic-based art seep out of the work, causing all sorts of unpleasant consequences (details below). Furthermore, the short lifespan of plastic art is at odds with the fact that most museums want to buy art that lasts centuries or at least decades… not years. Yet in the 1970s, 80s and early 90s, just as plastic sculptures and designer furniture were pouring in to museum and gallery collections, staff conservators were collectively sticking their heads in the sand about the inherent vulnerability of these objects… I mean, even though plastics have short lifespans, there are ways to extend them. But conservators weren’t acknowledging that plastics were problematic. It’s come to be known as “the plastics denial syndrome” and thankfully it’s now over, says Yvonne Shashoua, a conservation scientist at the National Museum of Denmark, in Copenhagen. Shashoua features heavily in an article I just wrote about how plastics are a serious problem child for museum staff and what can be done to improve some pretty impressive bad behavior. Case in point: the phthalate plasticizer added to make PVC (polyvinyl chloride) maleable has a tendency to leach out, so much so that small pools of the plasticizer collect in and around the art. These plasticizer puddles are not precisely aesthetically pleasing, they attract dust and actually the loss of the plasticizer destabilizes the plastic making it vulnerable to cracking. Then there’s this more nepharious example: Acidic gases percolate away from plastic objects made of cellulose acetate and then corrode nearby metals and textiles. For this reason conservators call cellulose acetate “the malignant plastic.” Cases like these forced conservators to take the degradation of plastics seriously. Check out the longer article to find out what museum staff are now doing to keep plastic art and artifacts alive and as well-behaved as...

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