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Popular Science: Painting with a surprise

It is good luck when an old and unrestored painting is acquired for pigment analysis, and even more so when there is a surprise in it. A group of chemists and geochemists from Great Britain, Belgium and the Czech Republic, which also included Professor Jan Jehlička from the Institute of Geochemistry, Mineralogy and Mineral Resources, analysed an oil painting from the 18th Century with the aid of Raman spectroscopy. The painting “Bird in Hand” was acquired by the passionate collector George Lester Winward, who thought it to be a work by Thomas Gainsborough, the renowned English painter of the 18th century.

 

The work of art is currently located in the de Brecy Trust collection. Because the painting's palette was still unknown, just like its author, and the work was available for analysis, it is clear that that the inherent curiosity of the scientists would show itself.

Raman spectroscopy is a very suitable tool for pigment studies of art works, because only a minute

The picture that undertook analysis: Bird in hand, photo: Edwards Howell

sample is needed for obtaining satisfying results. It has shown to be very suitable for distinguishing mineral and organic pigments and their binders. But even with the use of various techniques it is only possible to place an art work into a broad time scale because of the common usage of pigments over hundreds of years. The exposure of fakes is only realized through the identification of rogue pigments that didn’t exist at the supposed time of the creation of an art work. Chemical analyses can never fully authenticate an art work, but can expose a fake.

But let us go back to our painting of the boy. The analysis revealed remarkable combinations of pigments as well as an uncommon additive in the white colour – silica river sand and powdered glass – probably serving as a brightener. The most important discovery was the detection of a red pigment which has not yet been described in literature. It was recorded in mineralogical literature from deposits in Argentina, China and Iran in 1970 and first synthesized in 1980. So it is very unlikely that it was used intentionally in the painter’s palette. More likely it appears in nature together with other minerals commonly used for painting, such as hydrocerrusite which is used for the production of lead white. That might be a way to authenticate the author of the art work: to analyse white pigments from paintings that are known to be painted by T. Gainsborough and determine their mineralogical provenance. That could lead to supporting or undermining the assumption concerning the authorship of the painting.

Maybe we will soon learn the continuation to this story…

 

                                                                                                                                                            Radka Zelená

 

Edwards, Howell G. M.; Vandenabeele, Peter; Jehlicka, Jan; et al. (2014). An analytical Raman spectroscopic study of an important english oil painting of the 18th Century.  SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY  Volume: 118   Pages: 598-602.

 

 

 

 

Published: Aug 09, 2015 11:10 AM

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