Abstract: A composition useful for the protection of actinic light-exposed presensitized lithographic printing plates. The composition contains an effective amount of the di-potassium salt of hydroxyethylidene diphosphonic acid dissolved in water. The composition is applied to the surface of the revealed substrate of the plates after they have been developed but before treatment to heat, to prevent surface contamination from the heat treatment.

Abstract: The disclosure concerns an antibuckling apparatus for a lithographic plate or the like which is being cured in a UV post-curing apparatus. A source of UV radiation irradiates one surface of the plate as the plate is moved through a curing chamber along a predetermined path. An upper antibuckling device comprises a first pair of spaced elongated members which extend across the path of the plate and serve as a support for a plurality of upper antibuckling bars disposed between the radiation source and the upper surface of the plate. The antibuckling bars are disposed generally along the path of the plate but obliquely to the direction of the path, whereby the antibuckling bars do not interfere with irradiation of the entire width of the upper surface of the plate. A similar lower antibuckling device may be disposed beneath the plate on the side thereof not being irradiated.

Abstract: An improved lithographic printing plate prepared by exposing a lithographically suitable photosensitive sheet material through a mask or transparency, to radiation, developing the exposed sheet to remove unexposed light sensitive material and post-curing the developed sheet by exposure to high intensity radiation or air-baking at high temperatures.

Abstract: A method for preparing aluminum based lithographic printing plates which comprises treating at least one surface of an aluminum base sheet with lithographically suitable, photosensitive, preferably water-soluble, diazo composition and then applying to said surface a lithographically suitable photopolymerizable composition to yield the desired photosensitive lithographic printing plate of improved characteristics.