a composite web comprised of free standing plies is prepared with precisely even linear amounts of each ply , based on the principle of using a carrier ply of preferably heavy gauge plastic film . the carrier ply under controlled tension , is trained about the surface of revolution of a supply roll of a reinforcing scrim material . as the carrier ply is advanced , an exactly matched linear amount of scrim is deposited on one surface of the carrier ply , irrespective of the mismatched elongation properties of the scrim and carrier plies , respectively , and with minimal or no neck - down of the scrim . a liner ply of plastic film can be applied to the opposite side of the scrim using the same principles . the resulting web is ideally suited to be converted into filled , scrim reinforced , plastic bag structures .