34 phosphoric acid or one of the anions derived from such acid 34 includes metaphosphoric acid metaphosphate ion pyrophosphoric acid pyrophosphate ion dihydrogen orthophosphate ion hydrogen orthophosphate ion and or orthophosphate ion and is preferably orthophosphoric acid or its derived anions because of the improved results obtained the hydrophilic metal cation of this invention is a cation which when added to the conversion wash improves the hydrophilicity of the background of the printing plate it is theorized that this cation is adsorbed to the reaction product of the zinc cation from the photoconductive zinc oxide copy medium the organic amine compound and the phosphoric acid or one of the anions derived from such acid the metal cation preferably is aluminum cation however other cations such as those of titanium zirconium or tin can be used the organic amine compound of this invention is an organic amine capable of forming an insoluble salt with zinc ion in combination with the hydrophilic metal cation and phosphoric acid to thereby increase the hydrophilicity of the background areas of the electrophotographic zinc oxide copy medium processed the preferred amine is an alkylene amine such as diethylene triamine and more preferably a primary alkylene diamine such as ethylene diamine ethylene diamine is preferred because of the exceptionally good quality prints obtained with this amine compound the preferred alkylene diamine is one having from 2 6 carbon atoms between the amine groups the.