A printing defect characterized by the faint appearance of an undesired image on the reverse side of a printed sheet, originating from the sheet beneath it. Chemical ghosting, though rare, typically occurs with oil-drying inks and are believed to be caused by gaseous emissions of a drying ink reacting with the proper drying of the ink on the adjacent sheet, producing a "phantom" image, often of less gloss than the original image. (Chemical ghosting should not be confused with ink setoff.) (See also Mechanical Ghosting.) Chemical ghosting is also called fuming ghosting and gloss ghosting.