nitro benzene sulfonic acid m nitrobenzene sulfonic acid 2 chloro 5 nitrobenzene sulfonic acid 2 4 dinitrobenzene sulfonic acid p nitrotoluene sulfonic acid 3 5 dinitro p toluene sulfonic acid and the like the concentration of the nitrosulfonic acid may range from 2 to 10 percent by weight but is preferably from 3 to 8 percent by weight the adhesion promoting composition may also contain surfactants or water soluble polymers the inventors have found that the addition of non ionic surfactants and water soluble polymers are advantageous to the performance of the adhesion promoting composition in particular homopolymers or copolymers of ethylene oxide and or propylene oxide have been found to be useful in addition non ionic surfactants have also proven to be useful the concentration of surfactant and water soluble polymers in the adhesion promoting composition may range from 0 5 to 3 percent by weight but is preferably from 1 to 2 percent by weight finally it may be advantageous to incorporate thickeners into the formulation if the adhesion promoting composition is to be applied to vertical surfaces the chromating composition to be used in the process can be any composition capable of effectively creating a chromate conversion coating on the surface of the metal being treated in this regard the teachings of u s pat no 2 796 370 are herein incorporated by reference in their entirety the inventors have found iridite 14 2 a chromating solution available from macdermid incorporated of 245 freight street waterbury conn to be particularly useful in this regard the adhesion promoting composition and the chromating composition may be applied to the metal surface by either immersion spray or equivalent method the compositions should preferably remain in contact with the metal surface for a minimum of several minutes.