A lithographic printing surface is prepared using a thermal lithographic printing plate which requires no chemical development to remove areas of the imaged plate. The processless thermal lithographic printing plate has a sheet substrate; a porous, aluminosilicate hydrophilic layer on the sheet substrate; and a porous, thermally reactive imaging layer on the hydrophilic layer. The imaging layer is imaged using infrared laser radiation to produce an imaged layer. The imaged layer is treated with a conditioner liquid to produce a porous, planar, lithographic printing surface. By this method, the printing plate can be digitally imaged by infrared laser so that the imaged areas become ink receptive and the non-image area repel ink after simple treatment with a conditioner such as an aqueous surfactant solution such as a fountain solution containing an amphoteric surfactant.