a method and apparatus for forming film capable of being converted into bags in an form , fill and seal machine or for providing bags attached to each other in end - to - end relationship including relatively advancing a continuous sheet of thin plastic film along a path having a fastener station therealong , moving first and second thermoplastic flexible fastener members laterally from opposite sides of the sheet to extend transversely substantially to the center thereof and attaching said fastener members to the surface of the sheet whereby the sheet can thereafter be formed into bags in an form , fill and seal machine or folded longitudinally to join the fastener members and to form a side seal to form a completed series of bags by cross - seaming the material at predetermined spaced intervals .