Coated aluminum lithoplate and method

Claim 1

AN ALUMINUM LITHOPLATE WITH A LIGHT-SENSITIVE DIAZO RESIN COATING COMPRISING AN ALUMINUM SHEET, A SURFACE OF SAID SHEET BEING PROVIDED WITH AN ADSORBENT ALPHA-ALUMINA MONOHYDRATE CONVERSION COATING, ALKALI METAL DICHROMATE ADSORBED BY SAID CONVERSION COATING SoID ADSORBED DICHRONATE BEING OBTAINED BY TREATING SAID CONVERSION COATING WITH A SOLUTION CONSISTING ESSENTIALLY OF AT LEAST ABOUT 1 GRAM PER LITER OF ALKALI METAL DICHROMATE AND WATER MAINTAINED AT A PH BETWEEN ABOUT 3 AND 7, AT A SOLUTION TEMPERATURE BETWEEN ROOM TEMPERATURE AND THE BOILING POINT, AND A LIGHT-SENSITIVE DIAZO RESIN COATING ADHERING TO SAID CONVERSION COATING, SAID LITHOPLATE BEING CHARACTERIZED BY WATER-WETTABILITY OF NON-IMAGE AREAS OF SAID CONVERSION COATING FOLLOWING EXPOSURE AND DEVELOPMENT, AND BY ADHESION BETWEEN SAID DIAZO RESIN COATING AND SAID CONVERSION COATING WITHOUT EXHIBITING DELETERIOUS REACTION BETWEEN SUCH RESIN COATING AND EITHER THE CONVERSION COATING OR THE UNDERLYING ALUMINUM.