I can't find zero-rust prep step, which is supposed to adjust the ph on metal parts for best paint adhesion. I have used vinegar to wipe down galvanized duct before painting with good luck. Would this be okay if I follow up with a damp clean wipe down? I have a lot of engine parts and suspension stuff cleaned up after hot tanking them, but am concerned about possible caustic influence on the ph of the metal. Help! :confused: