Patent ID: 8419923

Claim:
A method for making a lithographic printing plate support comprising the steps of: (i) providing an aluminum support; (ii) treating said support in an aqueous solution; and (iii) graining said treated support in an electrolyte solution by applying an alternating voltage to said support thereby inducing a local current density (J) at the surface of said support, wherein said local current density J at time (t) fulfills the following equation: J ( t )≦ a+bQ ( t ) for t=0 to t=tf and wherein in the equation Q(t) is the integrated value of the absolute value of the local current density J(t) at time t: Q ⁡ ( t ) = ∫ 0 t ⁢  J ⁡ ( τ )  ⁢ ⅆ τ a is 5, 3.5 or 2.9, b is 10, 9.0 or 8.6, and tf is the time necessary to obtain a value of Q(t) equal to 80, 50 or 10 C/dm 2 , wherein the unit of J(t) is A/dm 2 .