Abstract: The invention provides a process for etching a metal surface by applying, to the metal surface, a solution of ferric chloride at an effective concentration, which solution also contains phosphoric acid. The etching is done in an etching tank and the effective concentration of ferric ions is maintained by diffusing an oxidizing agent which is chlorine gas or a compound which forms HOCl in solution through the tank. A number of other steps which may vary according to the type and grade of metal surface which is to be etched are also performed in terms of the process of the invention, both before and after the application of the etching solution to the metal surface. Metal surfaces etched according to the invention have a coating, for example polytetrafluoroethylene, subsequently applied thereto.