Protection of metals from corrosion

Claim 1

THE PROCESS OF TREATING BASE METAL ARTICLES OF THE GROUP CONSISTING OF FERROUS METALS, COPPER, ZINC, AND THEIR ALLOYS, FOR IMPROVING THEIR RESISTANCE TO ATMOSPHERIC CORROSION, PREPARATORY TO APPLYING A NONFERROUS FINISH WHICH COMPRISES TREATING THE ARTICLES TO RENDER SUBSTANTIALLY GREASEFREE AN EXTERIOR SURFACE TO BE PROTECTED, APPLYING TO THE GREASE-FREE SURFACE AN AQUEOUS SOLUTION CONTAINING AT LEAST ONE HUNDRED PARTS PER MILLION BY WEIGHT OF AT LEAST ONE COATING METAL SELECTED FROM THR GROUP CONSISTING OF CALCIUM, STRONTIUM, BARIUM, ZINC, CADMIUM, NICKEL, COBALT, AND MANGANESE, THE METAL BEING PRESENT IN THE FORM OF A WATER-SOLUBLE SALT, AND AT LEAST ONE MOLEUCULARLY DEHYDRATED PHOSPHATE, THE WEIGHT RATIO OF THE P2O5 CONTENT OF THE MOLECULARLY DEHYDRATED PHOSPHATE TO THE COATING METAL BEING BETWEEN 0.03:1 AND 7:1, THE PH VALUE OF THE SOLUTION BEING BETWEEN 3 AND 9 AND SUCH THAT AN AMORPHOUS COATING METAL PHOSPHATE FILM IS DEPOSITED ON THE BASE METAL WITHOUT VISIBLE ATTACK ON THE BASE METAL SURFACE, AND THEREAFTER DRYING THE ARTICLES SO AS TO PROVIDE A DRY FINISH-RECEPTIVE EXTERIOR SURFACE HAVING A SUBSTANTIALLY AMORPHOUS FILM THEREOVER, THE FILM BEING CHARACTERIZED BY A GOOD QUALITY OF BONDABILITY WITH NONFERROUS FINISHES.