TODAY we’re going to delve into a little used drawer in the file cabinet; the one labeled “ART.” Of course since this is a science and technology column, you might expect that would be a part of it, and you’d be right.
Scientists at the National Gallery in London are revealing the hidden secrets of some of the world's most famous paintings. They’re using a gas-chromatography-mass-spectrometer (GC-MS) to study the organic chemistry of old master paintings to understand how these paintings were made and how they’ve changed over time. The scientists are using the GC-MS to study the media used to bind the paint pigments, additions to the paint, like resins and the composition of old varnishes.
The results of this work have raised complex questions of disputed authorship and authenticity, and have revealed that some paintings are period copies and some are modern forgeries. The technique also reveals the original color balance of paintings.
One example is The Virgin and Child with an Angel, originally attributed to the Renaissance painter Francesco Francia and dated about 1490. The painting's authenticity was questioned in 1954 when another version appeared on the market. Finally in 2009, GC-MS testing on the paint media and varnish proved beyond a shadow of doubt that the Gallery's painting was indeed a fake that was painted in the 19th century.
The work is technically demanding. Only tiny fragments of paint and canvas can be used as samples, and the organic content can be very complex. The tested materials have usually changed over time and the analyses of the degraded materials have to be compared with assessments of the original chemical composition.
The National Gallery is featuring an exhibition called “Close Examination,” which presents some of the fascinating stories behind more than 40 paintings in the museum’s collection. The exhibition looks at some of the major challenges faced by Gallery experts: deception and deceit; transformations and modifications; mistakes; secrets and conundrums; redemption and recovery; and a special focus room relating to Botticelli. The exhibition features works by Raphael, Dürer, Rembrandt, and others. The very next time I’m in London, I’d love to go!
But the GC-MS isn’t the only way to study paintings. Even though you learn a lot, you have to take a small sample to use this technique. A group of researchers at McGill University in Montreal Canada has started using a non-destructive method to examine old paintings. They’ve started listening to them ... huh?
They’re using a technique known as photo-acoustic infrared spectroscopy, which can identify the composition of pigments in paintings that are decades or even centuries old. Pigments give paints their color, and they emit sounds when light is shone on them.
Photo-acoustic infrared spectroscopy is based on Alexander Graham Bell's 1880 discovery that solids can emit sounds when exposed to sunlight, infrared radiation or ultraviolet radiation. Advances in mathematics and computers have enabled chemists to use the technique on various materials, but the McGill team is the first to use it to analyze the inorganic pigments that most artists use.
The researchers have classified 12 historically prominent pigments by the infrared spectra they exhibit – i.e., the range of noises they produce – and they hope the technique will be used to establish a pigment database. Once this database is established, the technique will become yet another weapon in the arsenal of art forensic laboratories.
Obviously there’s a lot more to art than just looking at it!
Cruise on over to The Deep website at www.thedeepradioshow.com to learn more about art, science and many other topics. Enjoy!