The Courtauld Institute of Art’s expertise in preserving art works derives in part from its use of advanced lab techniques Of these, the most important is chromatography, explains its Head of Conservation.
Analytical techniques tend to be associated most with those sectors – pharma, life science and manufacturing – whose demand for such services operates at industrial scale and which have committed most to investing in relevant R&D innovation. Since the 1960s, however, the scientific laboratory has established a significant presence in another very different but high value market; fine art.
Much of this, says the Courtauld Institute of Art’s Head of Conservation Austin Nevin [pictured below], was down to the efforts of organic chemist the late John Mills. As Scientific Adviser to the National Gallery, Mills helped establish the institution’s annual Technical Bulletin in 1977 to encourage the scientific study of the materials and techniques of painting.
“If you mention anybody, [Mills] would be the one who’s important for introducing chromatography to museums,” acknowledges Nevin, who explains the National’s interest as in harnessing the science of soap making and soap and oil analysis for the analysis of painting.
Fast forward to 2000 onwards and the trend was established whereby conservators were expected to have stronger knowledge of analytical processes says Nevin, himself a trained conservator with a science background.
“What’s tricky for conservators is that there’s so much science that they have to decide what to learn. But it’s quite impressive that we now know about molecular processes that we did not know about 30 years ago.”
At the Courtauld, Nevin says, he looks for “good analytical chemists who can combine a knowledge of chromatography, microscopy and spectrometry”. Of chromatography, however, he admits, that “if I had one technique to go to, I would probably use that one”.
Whether distinguishing paint pigments or working with binding media, chromatography is vital. It remains the only method for identifying specific organic materials – essential, says Nevin, for analysing degradation of oils, identifying modern varnish or polymers or specific organic materials that make up dyes and pigments.
“Chromatography is one of the battle horses of conservation science but it’s also one of the most tricky and difficult techniques to master. And it’s not a technique that most conservation scientists are able to use, so we rely on specialists for it.
“We have real problems in conservation in cleaning certain surfaces, especially contemporary surfaces and also 20th century surfaces, where we have mixtures that we just cannot identify – and even identifying them might not solve the problem. But we are not experts in the chromatological analysis of polymers, therefore we need to find the experts and there are not many people or groups who focus on heritage science.”
This creates logistical challenges. While mainstream industry functions on principles that favour scale and standardisation, art conservation runs in the opposite direction: samples for analysis from historic works will be available in only the smallest quantities, while the retouching of art over centuries means that the materials employed may have changed considerably over time.
Also, reminds Nevin, some of the quality control aspects of industrial chemistry are less applicable as “we don’t have standard types of samples – one day we might be looking at a 20th century painting, the next an 18th century or something Egyptian.”
Cost benefit then is among the drivers for collaborative projects – whether with peers such as the Tate, academic leaders in the science including the University of Pisa, or industry.
“It’s [about] finding the groups that have the interest in biological as well as heritage science and are confident enough that they won’t destroy their instruments. That’s the biggest issue we have; most people will not risk putting a dirty sample – which is what we have – inside the machine and so therefore you tend to go to the people who really know what they’re doing.”
While his sector cannot attract levels of investment to become early adopters of innovative technology, Nevin is keen to tap into the benefits: “It’s [about] trying to find the links with the biological sciences and the pharmaceutical sciences, where some of the molecules that we’re interested in are precursors for drugs.”
Already, sophisticated chemistry has enabled use of samples for more analyses than previously possible and allowed detection of smaller molecules. Coupling chromatology with microscopy, he adds, provides a completely different arsenal of information.
Detection systems too have significantly improved the Courtauld’s ability to see and use smaller samples, “and small sample size is very important for us as we don’t have access to much material”.
Chromatography is one of the battle horses of conservation science but it’s also one of the most tricky and difficult techniques to master
Elsewhere, artificial intelligence systems allied to chromatography (currently pioneered by the likes of Fujitsu, see page 42) create exciting possibilities, says Nevin.
“If we start looking at really messy chromatograms, we [sometimes] don’t know what we have. I think with AI it would be possible to do a more nuanced interpretation of complex chromatograms.
“In the past we were asking questions like ‘Do I have collagen or not?’ and you would look for one specific marker of collagen. Now we’re asking ‘How was that collagen prepared? What animal did it come from?’ and sometimes you need more advanced techniques.
“I think AI could become very interesting for us if we were looking at a very complex fragmentation pattern, for example.”
Yet the learning process is reciprocal. Developments in organic chemistry have enhanced understanding of the relationship between varnished surfaces and environment and the limits of painting preservation – to the benefit of institute and science, reminds Nevin.
“We’re not end users only, we’re also contri-buting to the development of technology.”
