Method of treating iron or mild steel to promote the adherence of porcelain enamel, and stock so produced

Claim 1

A PROCESS OF INCREASING THE ADHERENCE CHARACTERISTICS OF AN IRON OR MILD STEEL STOCK OR ARTICLE INTENDED FOR COATING WITH PORCELAIN ENAMEL, WHICH PROCESS COMPRISES IN THE ORDER NAMED THE STEPS OF DEPOSITING UPON THE SURFACE OF THE STOCK OR ARTICLE A MATERIAL CHOSEN FROM A CLASS CONSISTING OF NICKEL, COBALT, MIXTURES OF THE TWO, AND ALLOYS RICH IN NICKEL, COBALT, OR BOTH, SUBJECTING THE STOCK OR ARTICLE TO A SCALE ANNEAL COMPRISING SUBJECTING THE STOCK OR ARTICLE TO HEAT IN AN ATMOSPHERE NO LESS OXIDIZING THAN AN ATMOSPHERE OF BURNED NATURAL GAS CONTAINING 11% COMBUSTIBLES BASED ON DRY GAS ANALYSIS AND HAVING A DEW POINT OF 150* F., IN A FURNACE AT TEMPERATURES OF SUBSTANTIALLY 1400* TO 2000* F. FOR A TIME OF SUBSTANTIALLY 2 TO 5 MINUTES, WHEREBY TO PRODUCE A DISTINCT SCALE, AND THEN ACID PICKLING THE ARTICLE AT LEAST TO THE EXTENT OF REMOVING THE SCALE FROM THE SURFACES THEREOF.