A method for increasing the corrosion resistance of a data/information storage and retrieval medium comprises sequential steps of: (a) providing a thin film data/information storage retrieval medium comprising, in overlying sequence: (i) a non-magnetic substrate; (ii) a layer stack including at least one magnetic layer; and (iii) a protective overcoat layer comprising a plurality of pores and/or channels extending therethrough; (b) maintaining the medium at an elevated temperature in a reduced pressure environment for an interval sufficient to remove moisture contained in the pores and/or channels of the protective overcoat layer; and (c) filling the pores and/or channels of said protective overcoat layer with a hydrophobic material.