Abstract: A method of cleaning metal surfaces comprising spraying a metal surface with an aqueous solution containing(a) at least one soluble salt of a carboxylic acid having 6 to 12 carbon atoms selected from the group consisting of aromatic carboxylic acids, aliphatic carboxylic acids and mixtures thereof,(b) at least one nonionic surface-active compound,(c) at least one quaternary ammonium surface-active compound,where the concentration of the active-substances (a), (b) and (c) in the aqueous solution is from 0.1% to 4% by weight and the weight ratio of (b) to (c) is from 20:1 to 1:1 and the weight ratio of (a) to (b)+(c) is from 20:1 to 1:20, where the pH of the aqueous solution is from 7.5 to 11.