Apparatus and method for anodizing supports for lithographic printing plate

An apparatus for anodizing one side of a substrate for a lithographic printing plate, said support comprising a web made of aluminum or an alloy thereof, said apparatus comprising:

• a backing roller which guides said web in a state of contacting the backing roller;
• at least one electrode which is arranged along the peripheral surface of the backing roller in a concentric arc acting as a cathode;
• at least two feeding cells, each feeding cell including a pair of feeding electrodes between which said web passes and being filled with feeding electrolyte solution for establishing electrical contact between said web and said feeding electrodes, at least one of said feeding cells provided upstream from the backing roller, at least one of said feeding cells being provided downstream from said backing roller with respect to a direction in which said web travels;
• an electrolyte solution which substantially fills the space between the backing roller and the electrode for establishing electrical contact between said web and said electrode;
• and
• wherein said side of said web to be anodized is a side facing said electrode in a portion of said web disposed in said electrolyte solution.

A method of anodizing one side of a support for a lithographic printing plate, said support comprising a web made of aluminum or an alloy thereof, comprising the steps of:

• guiding said web with said web contacting a backing roller being dipped in an electrolyte solution;
• supplying electric current to at least one electrode which is arranged along the peripheral surface of the backing roller in a concentric arc acting as a cathode;
• and
• supplying electric current to at least two electric suppliers, at least one of said electric suppliers being provided upstream from the backing roller with respect to a direction in which said web travels, at least one of said electric suppliers provided downstream from said backing roller with respect to said direction in which said web travels,
• wherein an electrolyte solution substantially fills the space between the backing roller and the electrode for establishing electrical contact between said web and said electrode, and
• wherein said side of said web to be anodized is a side facing said electrode in a portion of said web disposed in said electrolyte solution.