Patent ID: 8715403

Claim:
An acidic aqueous chromium-free composition (A) comprising a) at least 100 ppm to 5 g/l of metal ions (M) selected from the group consisting of ions of at least one of the elements nickel, cobalt, molybdenum, iron and tin, b) 1 mM to 100 mM/l of at least one water-soluble inorganic compound containing sulfur in an oxidation state of less than +6, c) less than 10 g/l of zinc ions, d) a total of 0.025 g/l to less than 1 g/l of dissolved phosphates, calculated as PO 4 ; wherein the acidic aqueous chromium-free composition (A) has a pH value in a range of 3.0 to 6.5.