Abstract: A method and apparatus for detecting patches or areas of relatively high gloss on a moving web, and thereby associated wrinkles or other defects, and signalling the presence thereof comprises an analog and/or digital optical reflectivity sensor for sensing gloss on the surface of the moving web, a web marking device adjacent the edge of the moving web for marking the edge of the web with a dye, and a microcomputer for receiving the output signal from the sensor(s) and for controlling the operation of the marking device. The apparatus may also include a warning device such as a light or horn. The apparatus and method have particular applicability in association with paper web re-reeling equipment.