Abstract: A self-cleaning web-threading apparatus for a web-fed printing press includes guide rails, a web leader, driver and a detergent supply. The guide rails define a web guideway along which a web is to be threaded through a printing press. The web leader travels along the web guideway in sliding engagement with the guide rails for threading the web through the press. The web leader is fabricated at least partially from a detergent-absorbent material for sliding contact with the guide rails. The driver drives the web leader along the web guideway. The detergent supply is disposed in a selected position on the web guideway for supplying a detergent to the web leader traveling along the web guideway to impregnate it with the detergent. The guide rails are cleaned by the detergent-impregnated web leader as it travels in sliding contact therewith.

Abstract: A continuous web of paper to be printed upon is unwound from its roll and, pasted to a pair of web leaders, thereby threaded through the printing press along any of a set of predefined alternative web guideways for each specific printing job. Each web guideway is defined by a pair of guide rails extending on either side of the guideway in parallel spaced relationship to each other. The pair of web leaders travel along the guideway by being slidably engaged one between each pair of guide rails. Since the guide rails are susceptible to dirt accumulation, due mostly to ink mist, the web leaders are each covered with woven fabric or like detergent-absorbent material for sliding contact with the guide rails. One or more detergent supply mechanisms are provided in positions of vantage along the web guideway in order to impregnate, as by roller-coating or spraying, each web leader with a detergent.