Abstract: A method for forming a breathable film material. A film which is a blend of a thermoplastic polymer and an inorganic filler is fed between a first roll and a second roll. The first roll has a plurality of toothed regions spaced apart by a plurality of grooved regions. The toothed regions include a plurality of teeth. The second roll has a plurality of teeth which mesh with the teeth on the first roll. As the film is fed between the first roll and the second roll the portion of the film passing between the grooved regions on the first roll and the teeth on the second roll remains substantially planar forming first regions in the film while the portion of the film passing between the teeth on the first roll and the teeth on the second roll are formed into second regions having raised rib-like elements.