properties thus in the preferred sealing layer blend the proportion is 85 lldpe and 15 ionomer for adequate sealing with lowest ionomer concentration to improve sealing if needed a blend of 80 20 of ionomer lldpe could be used to perforate the lay flat tubing both cold and hot needles were first tried needles which would penetrate both layers produced film which produced an unacceptably high number of split bags when the bags were heat shrunk around a product increasing the gauge or thickness alleviated the problem somewhat but to make a material thicker than necessary is an uneconomical consumption of relatively expensive thermoplastic materials in the prior art perforated films have been made in single layer form with hot needles cold needles and by the application of flame afterwards the single layer is formed into a tube or bag a typical bag of the single layer film that is sealed in panels is shown in u s pat no 4 503 561 which issued on mar 5 1985 to edward c bruno the bag disclosed in the aforementioned patent has at least two distinct panels of film and the panels have slits in them to provide a ventilated bag in order to use an economically thin tube material and to perforate the tubing in one operation so that a seamless tube can be used to produce a bag with a minimum number of sealing operations it has been surprisingly discovered that slits may be cut into the tubing to produce the required perforations the perforations may be put in by hand with a v.