Composition and process for treating metals

An aqueous liquid composition for treating metal surfaces, optionally after dilution with water, said composition comprising water and:

• (A) at least about 0.010 M/kg of a component of fluorometallate anions, each of said anions comprising (i) at least four fluorine atoms, and (ii) at least one atom of an element selected from the group consisting of titanium, zirconium, hafnium, silicon, aluminum, and boron;
• (B) a component of divalent or tetravalent cations of elements selected from the group consisting of cobalt, magnesium, manganese, zinc, nickel, tin, copper, zirconium, iron, and strontium in such an amount that the ratio of the total number of cations of this component to the number of anions in component (A) is at least about 1:5 but not greater than about 3:1;
• (C.1) at least about 0.015 M/kg of phosphorus atoms in a component selected from the group consisting of pentavalent phosphorus-containing inorganic oxyanions;
• (C.2) at least about 0.001 M/kg of phosphorus atoms bonded directly to carbon in phosphonate anions, the ratio of the concentration of moles of phosphorus atoms directly bound to carbon atoms in the organic phosphonates to the number of moles of phosphorus atoms in the inorganic phosphates in the same composition being within a range from about 0.05:1.0 to about 5:1.0;
• (D) at least about 0.10% of non-volatile contents of a component selected from the group consisting of water-soluble and water-dispersible organic polymers and polymer-forming resins, the amount of component (D) also being such that the ratio of the solids content of the organic polymers and polymer-forming resins in the composition to the solids content of component (A) is within the range from about 1:2 to 3:1;
• and
• (E) acidity.