from the holes 26 28 serves to pre soften only those portions of the male profile section 18 and female profile section 20 adjacent thereto those portions ultimately being the locations of side seal areas separating individual bags or packages further the hot air is directed at the actual engaging surfaces of the profiles rather than at the rear of the profiles as would be the case if air were directed from without rather than from within the package this permits the profiles to be softened to facilitate their being fused together in a tight seal in the actual manufacture of plastic bags or packages using the apparatus shown in the figure the plastic sheet material 10 is moved incrementally in amounts equal in length to the width of the bags or packages being manufactured each time the plastic sheet material 10 is at rest several actions take place simultaneously firstly blasts of hot air issue from holes 26 in guides 22 to pre soften adjacent areas of the male profile section 18 and female profile section 20 secondly vertical seal bars 30 compress the two lateral edges 16 of the plastic sheet material 10 together and seal them to the male and female profile sections and if desired each other outboard of the profile sections that is if desired the vertical seal bars 30 in addition to fusing the zipper to the plastic material may be used to form a seal outboard of the zipper by fusing the edges 16 to each other which must first be cut or otherwise ruptured by the consumer to provide access to the zipper for opening the final bag alternatively a separate.