Professor Robin Clark is applies robust scientific techniques to art and archaeology. Melody Thomas talks to him about authenticity.
Hoping to electrify the Timaru frozen meat industry, Robin Clark’s grandfather, an electrical engineer, immigrated to Christchurch from London in 1901. In 1939 Clark’s father was posted to Blenheim, and it was here that the curious boy started his education.
“From the word go I was attracted to science. I wanted to understand what things were, what properties they had, and what gave them their colours. Colour was the main and the abiding interest,” he says.
“[The science curriculum and laboratory facilities] there were not great, but they were sufficiently good to excite one’s interest, and this is the main thing.”
Clark fondly recalls early years spent running barefoot through paddocks, exploring hedgerows and catching tadpoles, when he wasn’t peering through his microscope or playing with his steam engine.
At 13 he was relocated again, this time back to Christchurch. There, Clark found he had to work hard to keep his place at the top of the class. “There were some very clever people you had to bat against in class or in debating competitions as well as on the sports fields.”
Clark went on to study chemistry, physics and mathematics at Canterbury University where the spectre of Ernest Rutherford still walked the halls.
“Every boy knew about Rutherford and how great he was. His key education was in Havelock at the head of the Pelorus Sound. At that time there was no secondary school in the whole province of Marlborough, and he had to sit an exam to get the one scholarship available to Nelson College. He didn’t get it the first time and had to wait another year before he did. New Zealand has a great history of producing people who are determined to get through obstacles and to bat well above their weight,” he says.
Clark left New Zealand in 1958 to study for a PhD on the chemistry of early transition metals.
“I set out to make new titanium compounds, then look at whether they were magnetic, what their structures and colours were and why they were that colour,” he says.
Clark’s interest in colour and ‘vibrational frequencies’ – or “the way a molecule vibrates and what that tells you about its structure” – led him to develop an interest in ‘Raman spectroscopy’, a field he has since made major contributions to, and which is the basis of his work with art and archaeology.
“[With Raman spectroscopy] you shoot a beam of light at something, nowadays a laser beam of one colour, and then you collect the light that comes back. What comes back is mainly the original frequency but also other colours, and these are the ‘fingerprint’ of what you hit.”  
A chance enquiry in the 90s lead Clark to apply Raman techniques to historical artifacts for the first time. A longstanding question regarding the pigmentation of a virgin’s dress was answered in moments with Clark’s techniques.
“I thought, ‘well if we can solve something that’s bothered the art world for a long time so quickly there must be other questions of these sorts’.”
Clark has since devoted considerable time to unravelling the mysteries of historic works, by identifying the pigments used and then looking at where and when they were sourced – to give a clearer indication of their age and likely authenticity.    
“If the pigment is synthetic we know the year that it was first made, so if we find something synthetic on something dated 1500 BC, the object clearly isn’t authentic. Also not all of these pigments are native, some were imported. A pigment found in Afghanistan couldn’t necessarily have been used in many places of the world, unless trade routes had been established. That’s the way we would attempt to determine if something is a forgery,” he says.
The process is simple, but Clark says the art world is not as keen to join forces as the science world.
“It’s the scientists doing all the running here, the art world doesn’t really want to ask the questions.  You’d think [authenticity] would worry the auction houses but I don’t think it does. It is said that 25% of artwork isn’t really what it says it is, and the person selling a piece of artwork doesn’t necessarily want to risk paying for investigations which may lead to his discovering that the work is a forgery.”
However, Clark says the relationship between the two historically estranged fields is much closer than it has been in the past.
“The art world has increasingly realised that they can only benefit from becoming involved with new scientific technology, and big institutions such as the Metropolitan Museum in New York, the Getty in Los Angeles and the Louvre in Paris are now equipped with a great deal of very specialist equipment.”
Clark, currently based at University College London where he is the Sir William Ramsay Professor emeritus of Chemistry, is in New Zealand as part of the Royal Society of New Zealand distinguished speaker public lecture series.
Science meets art: investigating pigments in art and archaeology, Soundings Theatre, Te Papa, 7pm, March 31.