A method for use in the manufacture of a filtration article includes providing a porous, fluoropolymer membrane, and applying a force to at least a portion of a first side surface of the membrane to modify the first side surface. The applied force may have a non-normal directional component relative to the first side surface. The surface modification may increase the density of the modified surface and/or reduce the porosity of the modified surface. Particle retention capabilities are thereby enhanced across the modified surface while maintaining permeability across the volume of the membrane.