Continuous strip closed-bottom open-mouthed packaging bags are produced by continually making, at spaced intervals in a continuous flattened tubular oriented plastic film supply, a transversely extending heat seal to define a bag bottom, and, adjacent each heat seal, perforating the two plies of the film supply with a blade heated to effect annealing of the edges of the perforations and having a serrated cutting edge with spaced deep recesses to define connecting tabs between perforations.
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