Close Examination: Fakes, mistakes and discoveries at the National Gallery, review

Scientific evidence can be invaluable but it has to be used with caution and always in tandem with historical research. For example, Corot’s ravishing plein-air sketch The Roman Campagna, with the Claudian Aqueduct has always been dated to about 1826, soon after the artist’s arrival in Rome. However, the green pigment called viridian that Corot used throughout the picture only became available to artists in the 1830s. The landscape wasn’t a fake and for stylistic reasons couldn’t have been painted later than the mid-1820s. All became clear when art historians did further research and discovered that the firm that sold artists’ supplies to Corot in Paris started making the newly developed colour available to selected customers in the 1820s, long before it came into widespread use.