Abstract: Composition, which comprises a latent activator and a colour former, a process for the preparation of these compositions, substrates coated with these compositions and a process for their preparation, a process for preparing marked substrates using these compositions and marked substrates obtainable by the latter process.

Abstract: A colorless or transparent composition comprises a charge-delocalization compound and a photoacid, wherein the photoacid generates an acid on irradiation or heating, thereby forming a colored change-transfer complex with said compound.

Abstract: An ink formulation comprises a marking component, e.g. ammonium octamolybdate, and a metal salt that absorbs laser irradiation at 780-2500 nm, e.g. reduced indium tin oxide, and thereby causes the marking component to change colour.

Abstract: The present application relates to a hand held device (1) for emitting a laser beam (8), the device comprising a laser source (2) having a power rating of at least 10 mW, an internal power supply (3) adapted to supply power to the laser source, and at least one optical element (7) for manipulating, in use, a beam (3) produced by the laser source.

Abstract: A laser-markable composition comprises a binder and an oxyanion of a multivalent metal.

Abstract: A method of ink-less printing comprises the steps of: providing a source (1) for emitting an energy beam,—providing an array of programmable shutters (3), each adapted for selectively blocking or allowing passage of at least some of an energy beam therethrough; providing a substrate (4) including an additive susceptible to changing colour when energized by the energy beam emitted by the source; selectively allowing passage of at least some of the energy beam emitted by the source through the array of shutters; and, positioning the substrate in the path of the energy beam that has passed through the array of shutters such that at least one desired point on the substrate is energized by said beam thus causing the additive to change colour at said point.

Abstract: A process for forming an image on a substrate, which comprises coating the substrate with an amine of molybdenum, tungsten or vanadium that changes colour on heating or irradiation as an aqueous dispersion or suspension or as a solution in an organic solvent. Also described is a coated substrate, wherein the coating is a substantially visible light-transparent layer comprising an amine compound of molybdenum, tungsten or vanadium, and a solution of said amine compound and a thermoplastic polymer or a photo-polymerisable monomer.