Disclosed herein is a pickling method for pickling metallic substrates making use of a phosphonate-free, aqueous pickling composition, a coating method for coating metallic substrates including the pickling method, and a method of using the compositions for pickling metallic substrates. The phosphonate-free, aqueous pickling composition has a pH value at 55° C. in the range from 5 to 9, and contains at least one copolymer, which is water-soluble or water-dispersible and selected from the group consisting of polyvinylpyrrolidones; the content of water is in the range from 95.0 wt.-% to 99.9 wt.-% based on the total weight of the composition.