Lithographic plates

Claim 1

THE PROCESS OF MAKING A LITHOGRAPHIC PLATE WHICH COMPRISES THE STEPS OF CLEANING A STEEL PLATE CAPABLE OF BEING MADE OLEOPHILIC, APPLYING A THIN COATING OF CHROMIUM TO SAID PLATE IN A CHROME PLATING BATH MAINTAINED AT A HIGH CURRENT DENSITY, THEN COATING A CHROMED SIDE OF SAID PLATE WITH A LIGHT SENSITIVE AND LIGHT HARDENABLE RESIST MATERIAL, FORMING ON SAID PLATE AN IMAGE COMPRISING AREAS TO BE INK-PRINTED AND AREAS NOT TO BE INK PRINTED BY PASSING LIGHT THROUGH A FILM BEARING SAID IMAGE WHILE SAID FILM IS POSITIONED ADJACENT TO SAID LITHOGRAPHIC PLATE, REMOVING UNHARDENED RESIST MATERIAL FROM THE PLATE, CHROME ETCHING SAID PALTE WITH A STANDARE ACIDIC ETCHING MATERIAL TO THEREBY REMOVE EXPOSED CHAROMIUM, WHEREBY AREAS TO BE INK-PRINTING ARE PRODUCED IN THE STEEL PLATE CORRESPONDING WITH THOSE AREAS OF TEH IMAGE OT BE INKPRINTED, NEXT CLEANING THE INK-PRINTING AREAS BY RUBBING ON THE PLATE A CLEAINING MATERIAL COMPRISING AN AQUEOUS SOLUTION OF ABOUT TWO PARTS BY WEIGHT EACH OF FERRIC CHLORIDE AND AMMONIUM CHLORIDE IN ABOUT THREE PARTS BY WEIGHT OF WATER, MIXED WITH A SOLUTION OF ABOUT 1 1/2 PARTS BY WEIGHT OF BISMUTH CHLORIDE, AND PUMICE POWDER, IN ABOUT TEN PARTS BY WEIGHT OF AN ALCOHOL, WHICH LEAVES THE INK-PRINTING AREAS OF THE PLATE BRIGHT AND SILVERY IN APPEARANCE, THEREAFTER REMOVNG RESIDUAL CLEANING MATERIAL WITH AN ORGANIC SOLVENT COMPRISNG ETHYL ALCOHOL, APPLYING A THIN COATING OF LITHOGRAPHIC VARNISH TO THE PLATE TO PROTECT THE INK-PRINTING AREAS THEREOF, NEXT WASHING FROM THE PLATE LIGHT HARDENED RESIST MATERIAL, THEN DRYING SAID PLATE AND REMOVING THE VARNISH LAYER, APPLYING A RUB-UP INK WHICH PREFERENTIALLY ADHERES TO THE INK-PRINTING AREAS AFTER A PASSIVATING AGENT FOR THE CHROME AREAS OF THE PLATE, AND FINALLY APPLLYING A PROTECTIVE GUM COATING TO THE PLATE.