Archive for category Methodology
The first thing I think of when someone says “painting” to me is the chemistry. In my younger years, I had the privilege to attend a lecture series on forensic analysis. I had originally thought that the talk on art fraud would be quite boring following the talks on arson and insurance fraud. How can you top smelling burnt articles to learn the differences between various combustable chemicals? Turns out that I could not have been more wrong; the one thing I remember most clearly from that day is the talk on art and the chemistry of the paints and canvases.
To me and you, a good copy of a painting could look like the real McCoy. With forensic analysis, hidden information, such as the true date range a pigment, varnish or canvas came from can be determined. Forensic scientists can do many things to date or verify the providence of a painting. Pigment dating. Carbon-dating. White lead dating. Infrared analysis. Microscopy. Two techniques that particularly impressed me where UV-fluorescence spectrography and X-ray diffraction and fluorescence. Certain paints and varnishes associated with historical developments have known responses to UV light, some fluorescing more than others, such that UV-fluorescence spectroscopy or spectrography can be used to determine which period a component of the painting does, or does not, come from. X-rays can also be used to determine the components of the paint and composition of the pigments; as art materials have advanced and new pigments have been developed, the purity or components present can reveal the likely age or exclude certain time periods where a pigment or component was known not to have existed.
Foiling criminals who would try to dupe us with copies of great art, chemists do that…
In the late 1800s, the time of Jack the Ripper, some of the early procedures that would become known as forensic science included inspection of a victim’s eyes for evidence. It was believed that eyes could capture the image of a killer, that the last thing that a victim would have seen would be retained on the retina like a final photograph trapped within the eye. There are reports that the police did photograph the eyes of victims in the hopes of finding such evidence. This method, called octography, became well-known because of its use in trying to identify Jack the Ripper. This belief was so widely held at the time that killers would destroy the eyes of their victims (Encyclopedia of Octography, Derek Ogbourne, 2008, p40).
History often repeats. Once again, the eyes are being looked to as a source of forensic information. Although it turned out that the image of a killer isn’t left on the retina of a victim, it appears that there is now technology that can now allow us to resolve the image of a person reflected in the eyes of another within photographs. This technology is now allowing the police to peer indirectly into the eyes of victims to identify the photographer, and even witnesses, to identify criminals by examining high resolution images of the reflections on the eyes.