Chromium appearance passivate solution and process

An aqueous acidic solution and process for treating metal surfaces, particularly zinc and zinc alloy surfaces, to impart improved corrosion resistance thereto. The solution contains effective amounts of- (A) hydrogen ions to provide a pH of about 1.5 to about 2.2, (B) an oxidizing agent, (C) at least one of iron, cobalt, nickel, molybdenum, manganese, aluminium, lanthanum, lanthanide mixtures or cerium ions or mixtures thereof, or instead of (C) iron and cobalt ions. Other treating solutions also incorporate, (D) chromium ions substantially all of which are in the trivalent state, and iron ions in combination with an additional metal from (C) or cerium ions, or (A), (B), (C) and (D) and (F), a bath soluble and compatible silicate compound or (A), (B), (C), and (D) and (G), a mixture of 1-hydroxyethylidene-1,1 diphosphosphonic acid and citric acid or mixtures of (A), (B), (C) and (D) with two or more of (E), (F) and (G). The treating solution may optionally further contain halide ions and a wetting agent