In the examination of the Allen Memorial Art Museum's recently acquired Domenichino <i>Landscape with Flight into Egypt, certain observations about the use of copper as a painting support were made. The plate appears to have been rolled with a primitive rolling mill. The front surface of the plate was prepared by scratching the copper, then coating the entire surface with an alloy of tin and lead, lead being the dominant component. There is no other preparation for the paint except possibly a clear film of oil which seems to lie between the paint and the lead-tin preparation. The use of copper to support small paintings gained some popularity in the Lowlands, Germany, and Italy in the first half of the 17th century. The examiners found the use of the lead-tin preparation unique among paintings on copper previously brought to the Laboratory. Palomino and Pernety, 18th century writers, both prescribe a gesso type ground on copper. There is some evidence that Domenichino used the metal preparation on his other paintings on copper. It would be interesting to know whether this is an idiosyncrasy of Domenichino's or of a region such as Bologna or Italy.