The invention relates to aqueous compositions containing one or more components selected from each of the groups comprising corrosion inhibitors, carboxylic acids, glycerol and derivatives, alcohols and polyethylene glycols, respectively, and tensides, which aqueous compositions are characterized in that they contain alkanolamines as the organic corrosion inhibitors, cinnamic acid and/or linear or branched aliphatic carboxylic acids or aromatic carboxylic acids as the carboxylic acids, glycerol and/or derivatives, dihydric alcohols and/or polyethylene glycols as the alcohols, cationic and/or nonionic tensides as the tensides and, optionally, UV-active ingredients, nonferrous metal inhibitors and/or light metal inhibitors and/or solubilizing agents. The compositions are used for preparing solutions suitable for the visual inspection and cleaning of surfaces of metallic structural members using the highlighting procedure or the flux procedure.