Abstract: A sealing method is provided for preventing leakage of toner from the initial fill or refill of a toner cartridge, in particular an IBM 4019/4029 cartridge used for a laser printer. The sealing method includes a tape, partially coated with adhesive, which extends substantially along the entire length of a slot formed by a pair of flexible guide members at the bottom of the toner hopper. Preferably, the tape has adhesive edge portions which attach to the guide members and a non-adhesive central portion which extends over the length of the slot. At least one end, and preferably both ends, of the tape extend from the ends of the slot and attach adhesively to one or more arms of a stirring member which is rotatably mounted in the hopper. Pairs of transverse slits which extend through the adhesive portion of the tape at a location between the ends of the slot and the ends of the tape enable the non-adhesive central portion of the tape to peel away from the adhesive portions upon rotation of the stirrer.