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Abstract:

A detailed examination was made of a painting from which small portions of the varnish had been accidentally pulled away from the surface. Beneath a thin coating of readily-soluble varnish, there was found a second coating, insoluble in all of the common solvents, which had separated from the paint in a few places. Xylene was able to penetrate beneath to this insoluble coating and to soften and swell the paint, permitting sheets of the coating to be pulled away with tweezers. Examination of these samples by infrared spectroscopy revealed that it was an epoxy resin. The evidence of this examination suggests that a genuine, but somewhat abraded, 17th century painting had been overpainted in a fuller range of color and chiaroscuro to improve its appearance and that new cracks had been cleverly incised over the original cracks. Finally, the work had been covered with a tough, insoluble epoxy resin, apparently to prevent detection of the readily soluble fresh paint. As a consequence, preliminary tests with solvents and examination by ultraviolet and infrared photography and by x-ray did not immediately arouse suspicion of extensive overpainting. This use of an insoluble epoxy resin and the precision of its identification by infrared spectroscopy is called to the attention of colleagues. Authors' abstract