When called to reframe pastels, charcoals and other works of art on paper which were kept under glass, framers often find a mirror image of the work on the inside of the glass, and tend to attribute it to improper framing practices. The author contacted two conservators for their opinion on the subject. Murray Lebwohl, a paper conservator, found off-setting mainly on black and white prints and drawings and thought that the main reason for off-setting is the action of direct sunlight on the artwork. Darker colors retain the heat longer causing some miniscule condensation on the glass. Gustav Berger, conservator of paintings, has seen offsetting occur not only on pastels, watercolors and prints but also on oil paintings on canvas, wooden panels and even copper. While off-setting of pastels is produced by simple static electrical charge, images produced by paint films are of a different nature. He supplied photographs to support his opinion that the pigment binders decay under the influence of light. The chemical reaction of their decay might set up electrostatic charges which precipitate their decay products onto the glass. -- AATA