art

What’s the sound of yellow ochre?

MCGILL (CAN)—Chemists have discovered that a technique known as photoacoustic infrared spectroscopy could help identify the composition of pigments used in artwork that is decades or even centuries old.

Details of the work are reported in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.

The technique is based on Alexander Graham Bell’s 1880 discovery that showed solids could emit sounds when exposed to sunlight, infrared radiation, or ultraviolet radiation.

“The chemical composition of pigments is important to know, because it enables museums and restorers to know how the paints will react to sunlight and temperature changes,” explains Ian Butler, lead researcher and chemistry professor at McGill University.

Advances in mathematics and computers have enabled chemists to apply the phenomenon to various materials, but Butler’s team is the first to use it to analyze typical inorganic pigments that most artists use.

The researchers have classified 12 historically prominent pigments by the infrared spectra they exhibit—in other words, the range of noises those pigments produce. They hope the technique will be used to establish a pigment database.

“Once such a database has been established, the technique may become routine in the arsenal of art forensic laboratories,” Butler says.

The next steps will be to identify partners interested in developing standard practices that would enable this technique to be used with artwork.

The research was supported by the National Science and Engineering Research Council of Canada.

More news from McGill: www.mcgill.ca/newsroom/

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