A flexible and oblong blade seal for sealing a gap between a door leaf and an adjacent surface includes A) a flexible outer material and B) a section with the sealing function (the sealing section), in which a barrier of a plurality of substantially parallel metal wires and/or narrow metal strips is embedded in the flexible outer material in such a way, that the wires and/or strips are arranged in parallel to the longitudinal direction of the seal. A method for mounting such seals and a method for producing them.