Electrolytic deplating process

Claim 1

A PROCESS FOR REMOVING FROM AN INERT, ELECTRICALLY NONCONDUCTIVE SUBSTRATE FILMS OF METALLIC CHROMIUM AND METALLIC GOLD DEPOSITED THEREON, SAID SUBSTRATE HAVING SAID FILM OF METALLIC CHROMIUM SUPERIMOSED DIRECTLY THEREON AND SAID FILM OF METALLIC GOLD BEING SUPERIMPOSED DIRECTLY ON SAID FILM OF METALLIC CHROMIUM AND AN ELECTRODEPOSITED METALLIC MAGNETIC FILM HAVING A THICKNESS IN THE RANGE 800-1600 A. AND CONSISTING ESSENTIALLY OF NICKEL AND IRON COVERING ONLY A PORTION OF SAID FILM OF METALLIC GOLD, WHICH COMPRISES INTRODUCING SAID SUBSTRATE CONTAINING THE FILMS OF CHROMIUM, GOLD AND NICKEL AND IRON DEPOSITED THEREON INTO AN AQUEOUS ELECTROLYTE AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 15*C. TO ABOUT 60*C. CONSISTING ESSENTIALLY OF AN ALKALINE ACTING ALKALI METAL COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDES, ALKALI METAL CARBONATES AND ALKALI METAL PHOSPHATES IN AN AMOUNT IN THE RANGE 0.2-12%, AND AN ALKALI METAL CYANIDE IN THE RANGE 0.2-12% DISSOLVED THEREIN AND, WHILE EMPLOYING THE THUS-COATED SUBSTRATE AS AN ELECTRODE, PASSING CURRENT THROUGH THE THUS-COATED SUBSTRATE TO EFFECT ANODIC DISSOLUTION OF SAID FILM OF METALLIC GOLD AND METALLIC CHROMIUM FROM THE AREA OF SAID SUBSTRATE NOT COVERED BY SAID METALLIC MAGNETIC FILM OF NICKEL AND IRON, SAID METALLIC MAGNETIC FILM AND THE FILMS OF METALLIC GOLD AND METALLIC CHROMIUM DIRECTLY UNDERLYING SAID METALLIC MAGNETIC FILM REMAINING UNDISSOLVED AND DEPOSITED ON SAID SUBSTRATE, THE THUS-COATED SUBSTRATE BEING INTRODUCED INTO SAID ELECTROLYTE SUCH THAT ANODIC DISSOLUTION OF SAID FILMS OF GOLD AND CHROMIUM IS EFFECTED SUBSTANTIALLY AS SOON AS SAID FILMS OF GOLD AND CHROMIUM COME INTO CONTACT WITH SAID ELECTROLYTE.