norman miller writer and photographer
norman miller writer and photographer norman miller writer and photographer norman miller writer and photographer norman miller writer and photographer

New Scientist

It took just seconds one afternoon in 2012 for self-styled art anarchist Wlodzimierz Umaniec to step up to Mark Rothko's 1958 masterpiece Black On Maroon at London's Tate Modern and scrawl his signature and a slogan across a corner of the world-renowned canvas with 'permanent' graffiti ink. The 18-month scientific analysis and painstaking restoration that followed shone a rare public spotlight on some of the complexities of art conservation.  

“One scientific challenge was that Rothko used so many different kinds of media to get a beautiful luminous effect – at times, fairly incompatible,” says Tate conservator Bronwyn Ormsby, before adding ruefully:  “In addition to the highly flowing and penetrating nature of the ink used.”  The damage was considerable. Glazed areas made with egg and dammar resin had been destroyed,  while in unglazed areas the ink had penetrated to the back of the canvas through complex layers of oils, pigments, colourants and glues.  

Nine months were spent analysing the ink, using gas chromotography to work out its precise chemical make-up then consulting on solubility parameters with solvent experts worldwide to whittle down thousands of possible combinations of chemical solvent to a shortlist of around 80 that might remove the ink without damaging Rothko's original materials. Even after hitting on a blend of benzyl alcohol and ethyl lactate, several months had to be spent testing removal methods on artificially aged canvas plus a 1950s primed canvas supplied by the Rothko family, before Ormsby and Barker finally began painstaking ink removal and restoration of damaged areas – using, as conservation ethics demand, fully reversible materials. “We found out during that process how hard it is to paint like Rothko!,” admits Ormsby.

The Rothko restoration was aided by a copious body of prior documentation on his materials and technique. But other artists are pushing conservation science into uncharted arenas with work fashioned from materials as different as soap and chocolate, plus bodily stuff like blood and faeces (yes, some modern art really is crap). Back in the early 1960s, New York's Museum of Modern Art (MOMA) turned down a Robert Rauschenberg sculpture over concerns about maintaining a work whose centrepiece was a stuffed Angora goat (vermin were one major worry).   

Old Masters are objects of flux and challenge too - pigments discolour, varnishes crack, canvases warp under centuries of complex stresses. The latter issue led London's Courtauld Institute of Art to team up with mathematicians at the UK's Warwick University to create a mathematical model predicting the behaviour of different canvases tensioned on different stretchers.

All this is what conservators call inherent vice - the archival constraints affecting different materials and their propensity to degrade. A well-known example is the nitrate film stock used for early movies, much of which has disintegrated or gone up in flames due to its combustibility. Dealing with inherent vice is spurring advances in both materials science and technology – though conservators must also heed aesthetic and ethical criteria which demand they see works as both technical objects but also unique – and often hugely valuable - cultural ones.  “You didn't forget it was a Rothko - but we became focused on the problem of the ink,” explains Ormsby. “Then when it was back on display we had to readjust to it being on the wall as a painting again.”

Conservators today are as likely to have backgrounds in chemistry or physics as art history, and rather than muttering about gestural impasto they  pore over readouts from x-ray analyses, advanced microscopy and various forms of spectroscopy. “The founding of museum laboratories was a turning point - at Harvard's Fogg Art Museum in Massachusetts and the Louvre [Paris] in the 1920s, then here in the 1930s,” says Marika Spring, Head of Science  at London's National Gallery.  

Multiple techniques came together in a 2011 investigation into why some of Van Gogh's famous painted sunflowers had turned brown, while others remained unaffected. A team spearheaded by doctoral researcher Letizia Monico and Koen Janssens, professor of chemistry at Belgium's University of Antwerp, analysed the relevant chrome yellow pigment - aka lead chromate – using minute samples from the paintings as well as some of the artist's left over 19th century paint tubes.

X-ray fluorescence (XRF) determined elements present in the offending pigment using a fine x-ray beam to induce changes in energy levels of its constituent atoms, triggering the release of secondary x-rays whose energies could be correlated to each element present. Fourier transform infrared spectroscopy (FTIR) then obtained more detailed structural information by bombarding samples with infrared radiation and observing characteristic absorption patterns.  Raman Spectroscopy (RS) further bolstered the data by firing a low powered laser onto the painted surface and referencing the spectra scattered back. Finally, a variant of XRF called XANES (X-ray absorption near edge spectroscopy) probed the precise chemical state of atoms in the pigment.

The team discovered around two-thirds of the chromium in the darkened samples had changed from bright yellow chromium(VI) to the darker green chromium(III), known to artists as viridian green. And mixing yellow and green gives brown – problem solved. Only why did the change occur only in some of Van Gogh's chrome yellows?...  The reason, ironically, turned out to be the artist's efforts to make some of his sunflowers even brighter by mixing yellow pigment with a white powder based on lead sulphate - and sulphate-laced chromium turns out to be horribly prone to darkening. Tests simulating long-term exposure to light showed just how bad this case of inherent vice was. “Within three weeks of exposure to UVA light the bright yellow paint turned chocolate brown,” says Janssens.

Damien Hirst provides a contemporary example of an A-list artist inadvertently hitting snags due to a materials science mistake. In Hirst's case, the issue concerned his iconic 1991 work The Physical Impossibility Of Death In The Mind Of Someone Living, consisting of a shark floating in a giant vitrine of preserving solution. But Hirst's shark soon began to decompose - the liquid clouding along with an accompanying stench and wrinkling of the shark's skin.

Despite its increasingly sorry state, the work was bought in 2004 by a US collector for several million dollars - a move which prompted a first major attempt to solve decomposition issues by skinning the shark, tanning its hide, then draping it around a fibreglass frame. Unfortunately, this made an object intended to evoke (meta)physical fear look more like a cheap prop at a Jaws convention. So Hirst finally called in Oliver Crimmen, Senior Fish Curator and preservation maestro at London's Natural History Museum, to remake the sculpture with proper conservation in mind. 

“Preservation is an ongoing experiment,” says Crimmen, as he hauls on a tangle of clanking chains in the bowels of the museum to reveal a huge tank full of big fish and snakes immersed in a dark brown bath of alcohol. “There's a lot we don't know about the chemistry. To a great extent it depends on what you want to do with a specimen.”

And that proviso was important because, while Crimmen firmly backs alcohol as the best technical preservation medium, an artist concerned with aesthetics might go for its more transparent rival formalin instead. So it proved. “Damien said formalin is part of the whole art work itself - he likes the colour,” confirms Crimmen, before adding that the flammability of alcohol was another issue when it came to sticking a huge tank of the stuff in public galleries or transporting work by plane.

But if Hirst's choice of preserving liquid wasn't the key problem itself, what had gone wrong? “When I went to look at the specimen I saw definite tissue shrinkage manifesting in the skin, due to improper fixation inside the body,” says Crimmen. “If you fix tissue in formalin it's got to get all the way in, and the only way to do that is to inject. And you couldn't really choose a more problematic animal than sharks. Their body cavity is largely taken up by this enormous liver, and if it starts to break down – which happens if the fluid is not properly injected – the whole thing starts to shrink.” Crimmen finds no fault with Hirst, though. “It was a very easy mistake to make – little information would have been available to him. In fact, in museums large sharks were very often stuffed! He applied the right techniques in the right way but not quite thoroughly enough.”

Hirst's aesthetic decision to use formalin rather than alcohol is an example of the challenges posed by the interplay of inherent vice with artistic knowledge and intent. “When I lecture at art schools, I am surprised how little information about art materials is taught,” says Glenn Wharton, Clinical Associate Professor of Museum Studies at New York University.

Take plastics. In the 1920s and 30s, artist brothers Naum Gabo and Antoine Pevsner made a series of abstract sculptures in cellulose nitrate and cellulose acetate, following a modernist credo of testing the artistic potential of new materials. They knew nothing of plastic's vulnerability to rapid disintegration, discolouration, crazing and warping, or going sticky as plasticisers migrate out of the material onto its surface. Today, Gabo and Pevsner's sculptures lie in tatters in museum back rooms as prime examples of what conservators have dubbed 'dead art'. “It's sad,” sighs Bronwyn Ormsby. “But in some ways on a material level all we can do is analyse it, and if it's gone it's gone.”

Institutions increasingly rely on questioning and negotiation with artists before acquiring a work. “At Tate we have a lengthy discussion around longevity and change,” explains Ormsby. “Some artists want change to be evident, others want preservation as much as possible.” But what if the artist is no longer around to ask? Is it acceptable to make replicas of dead art? “That's something we've grappled with re the Gabo sculptures,” admits Ormsby. “Conservation can explore questions in terms of 'there are ways we can replicate'. We got as far as creating 3D digital models to have replicas made – though we haven't yet.”

Having the artist on hand can certainly clarify procedure in some cases. Sculptor Tom Claassen solves issues around his use of highly degradable rubber by telling conservators how to remake his pieces every ten years. Remaking also underpins the approach to a giant cube of lard sculpted with her teeth that is part of Janine Antoni's work Gnaw, which New York's MOMA recasts for every exhibition using moulds replicating Antoni's bite.

More problematic is the same artist's Lick And Lather. This series of busts of Antoni's torso feature 14 cast in chocolate which she has licked, and 14 cast in soap which she bathed with (it's to signify ageing apparently). While the materials' inherent vice can be dealt with by recasting the busts when they deteriorate, what about the licking and bathing? If someone else licks the chocolate is it still a work 'by' Antoni? Go figure.

Other artists explicitly challenge the concept of conservation, such as painter Anselm Kiefer. His monumental canvases embody the chaos and destruction he saw growing up in Germany's blasted post-war landscape, using techniques such as attaching electrodes to paintings with metallic content to bloom colourful oxides or spattering works with molten lead and acid. Canvases are sent to galleries in full expectation that bits of them will fall off during transit. “It is not so easy having a painting of mine,” Kiefer once noted mischievously.

Technology itself suffers from inherent vice. Obsolescence or breakdown make migration (upgrading from old to newer media) and emulation (simulating an older technology with a newer one) part and parcel of conservation debate in the field of video, film and computer art. Some artists acknowledge the issues and try to help. When London's Tate Gallery bought Michael Craig-Martin's 2003 work Becoming – an endlessly changing LCD screen computer-generated animation - the artist provided its basic source code as a cornerstone for future exhibition on whatever screens might be around in the future.

Some works resist such future-proofing, however. While late artist Nam June Paik was famously flexible regarding curatorial display choices, his work itself can pose problems. Take his 1986 piece Video Flag, based on a kaleidoscopic wall of 70 cathode-ray tube TVs whose fuzzy scan-lined pictures are integral to the work's appearance. Old TVs break down – plus they can't simply be put in long-term storage as they need periodic powering up to keep the diodes working. After initially scrambling to buy old CRT sets on eBay, conservator John Hirx decided emulation was the only long-term answer, making new sets that capture as closely as possible the look and feel of the old.   

Such interventions highlight a tension between artists' wishes, the object itself, and the wishes of owners, whether a gallery or collector. Given the vast monetary value of some art, perhaps it's no surprise the law has weighed into the debate - though legislators have reached different conclusions on either side of the Atlantic. 

Since the 1880s, Europe's Berne Convention has protected artists' right to maintain the “integrity” of their work from “distortion, mutilation or other modification” - and conservation could be counted as “other modification” to a litigious artist. But in 1990, America's Visual Artists Rights Act (VARA) created a conservators' charter by stating “the modification of a work of visual which is the result of conservation... is not a destruction, distortion...or other modification.” So on one side of the pond, moral rights veer towards the artist, on the other towards the object.

In the end, perhaps best to just enjoy art as a manifestation of human creativity and freedom of expression, however it is made or displayed. “I would never advise an artist not to use ephemeral media - or a curator not to acquire the work,” says Glenn Wharton. “If art production was driven by durability alone, everything would be carved in granite. What a boring world that would be.”


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