An offset printing defect characterized by the appearance of faint replicas of printed images in undesirable places, produced in one of two ways. Mechanical ghosting is characterized by the appearance of a "phantom" image on the printed side of the sheet; it appears during printing and is easily detectable in the delivery tray. It can be caused by such things as ink starvation, as heavily-inked areas on the plate aren't always adequately reinked by the form roller, or by incorrect-diameter form rollers. Chemical ghosting, also called gloss ghosting or fuming ghosting, is characterized by a "phantom" image on the reverse side of a sheet originating from the sheet below it (not caused by ink setoff), and typically results from an ink reacting with and altering the drying of the ink on the sheet on top of it. (See Mechanical Ghosting and Chemical Ghosting.) Ghosting can also refer to a faint reproduction of an image without actual ink transfer.
Ghosting is also an alternate term for a flexographic printing problem more commonly known as mechanical pinholing. See Mechanical Pinholing.
The term ghosting also describes a defect of screen printing, characterized by a faint reproduction of the printed image beyond the edges of the stencil, caused by an improperly tensioned screen fabric which, following a squeegee stroke, creeps in the direction of the stroke. Ghosting in screen printing also refers to the reproduction of a printed image on the reverse of the substrate lying on top if it, caused by ink setoff.