Difficult business of
I had occasion recently to speak – fortunately on a theme that I knew something about! – to a group of very distinguished chemists. They were meeting for their annual, national conference in Chandigarh, and, following a practice established by them, they had invited, for an evening lecture open to the public, someone from a field truly and far outside their own highly arcane areas. I enjoyed the experience, and they were very gracious (although what the learned scientists got out of my lecture only they would know).
This was a seemingly odd
coming-together: of chemists with an art historian. But, on thinking
again, perhaps not all that odd, considering how materially the world
of art and art historians relies upon the knowledge and the skills
that chemists, among other scientists, possess. One can think of
countless things that one turns to them for: an understanding of
pigments and other materials, for instance; for conservation and
restoration; for determining the age of objects, in many cases, and
for their authentication. We were not speaking of these matters on
this occasion, but thoughts such as these were not far from my mind.
And certainly when – soon after this encounter with the chemists –
I chanced upon an article involving the authentication of a singularly
beautiful Southeast Asian bronze, a Maitreya figure, I read it with
more than usual interest. The tall and elegant bronze, now in the
Ellsworth collection in the US, purported to belong to the 6th or 7th
century, and was said to come from Cambodia.
But doubts had been raised about its authenticity, and the matter was referred to a team of experts, headed by Anna Bennett. The article dealt with the manner in which this team went about their task, the scientific methods they employed, before a pronouncement – their conclusion was that it was genuine, and did belong to the period claimed for it – was made. The whole process is too detailed for me to go into here, but what I found very absorbing and useful was the summary, given towards the end of the article, of the range of analytical techniques employed in the course of the examination. I draw attention to these here – even though I understand
very little of it myself – simply to underscore how complex these matters are, and how sophisticated these investigations can be. The experts emphasised, in their conclusions, that no one method should be considered infallible, and that not only is a combination of techniques desirable but also that a host of other factors – here is where art history, pure and simple, comes in – including context and style, have to be taken into account before any firm conclusions are drawn.
But, to go back to the scientific methods. There are many of them, and to understand them one needs at least a modicum of knowledge of the techniques involved: something that I do not have. But let me try and put them as briefly and clearly as I can, basing myself on what I read. The first method used in this case was that of low power microscopy. Clearly low power magnification yields much information: corrosion of metals takes place over long periods of time, and occurs as a result of the metal surface coming into contact with pollutants etc. which causes a patina to form on ancient objects. A faked patina can, however, be detected through this method. Then there is X-radiography in which the object is irradiated with X-rays. These rays pass through the object in different amounts, and thus help to reveal whether an object has been joined or repaired by soldering etc. Ancient repairs can be made out from recent ones, and pastiche objects can be identified.
The third method used was that of metallographic analysis in which the crystal structure of a metal can be studied through the removal of a small section from the object. False layers of corrosion show up through this. Then, there is elemental analysis, aimed at determining the constituents of alloys. Since much research has already been done on the composition of ancient alloys, and it is known that certain elements rarely occur as constituents of ancient alloys, results obtained through this method can be compared with known information, and conclusions drawn. Among the most powerful scientific tools employed in this field is thermoluminescence dating. Used generally for ceramics, it relies upon the fact that impurities within clay deposits, such as quartz, absorb radioactivity from other elements, causing the release of electrons, which are then fired, etc. The build-up of radioactivity in the object is proportional to the time elapsed since firing, and tiny samples taken from the object, when heated, emit light which is measurable, yielding information about the time elapsed since its making. Finally, there is radiocarbon dating, used generally for organic materials. Two isotopes of carbon, present in the atmosphere, – carbon 12 and carbon 14 – are taken up by a living organism at a constant rate. However, at ‘death’, this uptake ceases and the decay of carbon 14 to carbon 12 proceeds (the half-life of carbon 14 is close to 5730 years), leading to conclusions about the date of the sample taken being determined from the degree to which the decay process has proceeded.
All this sounds remarkably complicated, and the matter is compounded further by the fact that there are margins of error, and many hazards, such as samples being contaminated. But there is no getting away from the fact that much – a great deal, in fact – can be gained from the use of these methods. In the matter of authentication and dating, the scholar’s eye may remain the ultimate test perhaps, but there are always friends in the world of science that those inhabiting the world of art can turn to.
While going through the article on
authentication techniques that I have referred to above, I also saw some
rivetting photographs, taken strictly with the scientific end in mind. One of
these, a ‘photomicrograph’ of a tiny section removed from the right foot of
the sculpture in question, I found visually exciting, like a work of art
complete in itself. With its subtle sea-green and blue colouring, and its
animated air, it appears to be an image of a rough, agitated sea. Putting one in
mind of Hokusai’s magnificent rendering of the ‘Wave’, or one of Caspar
David Friedrich’s eerie but majestic landscapes with barren rocks.