The present invention provides a kit of parts for preparing an alkaline processing liquid for use in preparing a lithographic printing plate according to the silver salt diffusion transfer process, and comprising all necessary active compounds for preparing said alkaline processing liquid, said active compounds being comprised in parts physically separated from each other, at least one of said parts comprising an inorganic alkali in solid form, at least one of said parts comprising an alkanolamine as silver halide solvent and at least one of said other parts comprising a hydrophobizing agent and being substantially free from inorganic and/or organic alkali.