Decades ago, the work had been slathered with a layer of acrylic resin varnish ... As with any good Impressionist, Monet was creating less a finished painting than an impression of one.

The Warhol painting, titled “Colored Campbell’s Soup Can (Emerald Green), 1965” is acrylic, spray paint, and silk-screen ink on linen, according to court filings. The Monet is an oil-on ...