Method of coating metal and articles produced thereby

Claim 1

IN A PROCESS FOR COATING METAL THE STEPS OF DEPOSITING ON CLEAN METAL SURFACE A LAYER OF COATING COMPOSITION COMPRISING A DISPERSION OF ZINC DUST HAVING AN AVERAGE PARTICLE SIZE OF ABOUT 3 MICRONS, AT LEAST 90% OF WHICH IS CAPABLE OF PASSING THROUGH A 400 MESH TYLER JSIEVE IN AN AQUEOUS SOLUTION OF AN ALKALI METAL SILICATE CONTAINING ALKALI METAL CHROMATE, THE RATIO OF ALKALI METAL OXIDE TO SILICA DEFINED IN MOLES BEING 1:2.3 TO 1:3.0, SETTING THE ZINC DUST-SILICATE LAYER BY HEATING, TREATING THE SET SILICATE LAYER WITH A DILUTE AQUEOUS SOLUTION OF PHOSPHORIC ACID OF A CONCENTRATION LESS THAN 2% WHICH REACTS WITH THE SURFACE OF THE ALKALI SILICATE LAYER AND WITH THE ZINC THEREIN TO FORM A SALT LAYER AT LEAST A PORTION OF WHICH IS INSOLUBLE ZINC PHOSPHATE, DRYING THE SALT LAYER, AND THEREAFTER APPLYING AN OIL BASE DECORATIVE COATING TO THE DRY SALT LAYER.