Carol Vogel’s fascinating story on the restoration of Jackson Pollock’s One in the New York Times today has this interesting chapter where a combination of archival and scientific work revealed the painting had been slightly doctored after the artist’s death to make it more saleable:

The process began, as most restorations do, with a feather dusting. From there, James Coddington, chief conservator, and Jennifer Hickey, project assistant conservator, began to tackle the decades of grime covering the large painting, which is 9 feet high by 17 ½ feet across. They used sponges, moist erasers and cotton-tipped swabs soaked in water and a gentle, pH-adjusted solution.

Pollock’s drip paintings are complex, highly textured compositions with multiple coats of dripped and poured paint.  […] But when the conservators started to study these layers with X-rays and ultraviolet lights, certain portions of the canvas didn’t resemble Pollock’s style of painting at all. The texture was different, suggesting repetitive brush strokes not seen elsewhere in his work. […]

Museum officials did know that “One” had once belonged to Ben Heller, a dealer and a close friend of Pollock’s. The painting had also been in a traveling exhibition in the early 1960s. When they began researching that show they unearthed crucial evidence: a photograph taken in 1962 by a scholar in Portland, Ore., revealed that the painting had none of the questionable, uncharacteristic areas they had discovered. […]

“We presumed it was to cover up some damage, but we didn’t know how extensive it was,” he said. Studying these areas with an ultraviolet light, the conservator saw small cracks below the surface of the paint. Presumably the later painting was an attempt to cover the cracks, perhaps to make the painting more salable.