The author introduces the study of the condition of art, and how paintings in particular change in appearance over time. He explains some basic technical concepts and the technologies used to study art works, then discusses art that has been destroyed, cracks and flaking, impermanent pigments, darkening, and cleaning. Most of the paintings discussed are from London collections, particularly the National Gallery. Distributed in the US by Casemate. Annotation ©2016 Ringgold, Inc., Portland, OR (protoview.com)