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 hydrophilic layer on the sheet substrate; and a thermally sensitive imaging layer on the hydrophilic layer. The hydrophilic layer contains about 30 weight % of an aluminosilicate or clay, and preferably has an exterior surface which is micro-porous. The imaging layer preferably is micro-porous. The imaging layer is exposed imagewise using infrared laser radiation to produce an imaged layer. The imaged layer is treated with a conditioner liquid to produce a lithographic printing surface. By this method, the printing plate can be digitally imaged by infrared laser radiation so that the exposed areas become ink receptive and the non-exposed areas repel ink after simple treatment with a conditioner such as an aqueous surfactant solution such as a fountain solution containing an amphoteric surfactant.