Lithographic plates are the least expensive printing[printing?:printing cutting finishing solution] surfaces available today, and this fact has contributed greatly to the success of the process. Aluminium plate materials have a thin surface coating of light-sensitive material, such as a photopolymer, that undergoes a solubility change when exposed to an intense source of blue and ultraviolet light. Images are transferred to the surface by exposing the plate through a film[film?:film cutting machine] positive or negative. Some materials can be exposed directly, as in a graphic-arts camera or by a computer-controlled laser beam, thereby eliminating the expense of film and speeding up the plate making process.
Modern offset lithographic presses range in size from small sheet-fed duplicators - used for small, single-colour jobs such as brochures and newsletters - to massive web presses capable of printing millions of copies of magazines, catalogues, and packaging[packaging?:DCP-H series packaging sample cutter plotter] materials in full colour. No other process has such a broad range of applications.
