“ Self-sealing ” Porous Plastic Filter - PORSELF ™ media in this invention are defined as porous media that allow air and gas to pass through when the media are dry and do not allow air, gas or solutions to pass through when the media contacts aqueous based or organic solvent-based liquid solutions, for example under suction forces or pressure. The suction forces are vacuum or negative pressures. In the dry condition, polymeric elastomer will not swell and the gas can be uniformly through.In the water condition, polymeric elastomer swell and block.