Abstract: A gum solution is provided which comprises a film-forming hydrophilic polymer or surfactant, and a salt formed by reaction of an acid, selected from phosphoric acid and phosphorous acid, with a di- or tri-alkanolamine. The gum solution is suitable for developing and gumming a lithographic photopolymer printing plate precursor. Also provided is a method for preparing a lithographic printing plate wherein this gum solution is used, and whereby printing plates are obtained which exhibit an improved clean-out performance.