Electrochemical roughening of aluminum for printing plates in nitric acid and complex fluorine compound

Abstract From the Canadian patent

The invention relates to a process for the electrochemical roughening of a plate of aluminum or alloy thereof which is useful for a printing plate support comprising the steps, of (A) immersing the plate in an aqueous mixed electrolyte solution containing (i) from about 0.3 to 4% by weight of HNO3 and (ii) at least one further inorganic electrolyte comprising an inorganic fluorine compound which is present in the form of an acid or an alkali metal salt and which contains an anion comprised of fluorine and at least one further element such that said mixed, electrolyte solution contains from about 0.05 to 5% by weight of said fluorine compound; and (B) applying an alternating current to the …