Inland Steel Company

Lenin F Martinez

Brian A Sok

Albert Ray Mullins

Griff W Froman

A process of making a one-side-only coated endless metal sheet in which a sheet initially having a protective metal coating, such as zinc, on both lateral surfaces thereof is subjected to an electrolytic treatment which removes the protective metal coating from only one side of the metal sheet by continuously passing the metal sheet through an electrolytic treating chamber containing as an electrolyte bath a strongly acidic aqueous solution, such as sulfuric acid, having a pH from about pH 0.1 to 2.0, and preferably about pH 1.0, or a strongly alkaline aqueous solution, such as sodium hydroxide, having a pH of at least about pH 11 and preferably above pH 11, with said metal sheet being guided between spaced anodic and cathodic electrodes immersed in said electrolyte bath so as to establish a cathodic current between said anodic electrode and the adjacent surface of said metal sheet which is made cathodic and establishing an anodic current from a second rectifier between said cathodic electrode and the adjacent surface of said metal sheet which is made anodic, and maintaining the anodic current at a current density level so as to maintain the surface of said metal sheet which is to remain coated completely cathodic and effects complete removal of said protective metal coating from the anodic surface during the period said sheet remains in said electrolytic treating chamber, and with the cathodic current maintained at a current density level below said anodic current density level but sufficiently high to neutralize the E.M.F. generated when the said protective metal coating is immersed in said electrolyte bath.

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Hammond, IN, United States of America

Lenin F Martinez