Brings together, for the first time, Lucian Freud's oil on copper paintings, including his lost portrait of Francis Bacon and two works that have never been reproduced before In the early 1950s, Lucian Freud produced several works in oil paint on copper, a technique favored by 17th-century artists such as Rembrandt and Frans Hals, but unusual for a 20th-century painter. Originally thought to be only a handful, Freud in fact painted...