I stripped down some horns from my Packard. They are steel and either cast (potmetal) or aluminum. Anyway, after using the afterblast, and wiping off, after drying overnight, I am getting a white crust forming. Even after re-washing with a mild detergent and drying, it is still appearing. Any thoughts on what it might be? I’m thinking its a salt leaching from the metal. Would vinegar be the thing to neutralize it?