Laser Imaging

A method for forming an image on a substrate, which comprises applying onto the substrate an ink formulation comprising a marking component and a metal salt that absorbs laser irradiation at 700-2000 nm and thereby causes the marking component to change colour, wherein said method further comprises irradiatingthe formulation with a laser.

An ink formulation comprising a marking component and a metal salt, wherein the marking component in the absence of the metal salt undergoes a colour change in response to laser irradiation at a wavelength above 2000 nm but not between 700-2000 nm, and the metal salt absorbs laser radiation at 700-2000 nm thereby causing the marking component to change colour.

A method for forming an image on a substrate, which comprises applying onto the substrate an ink formulation comprising a marking component and a metal salt, wherein the marking component in the absence of the metal salt undergoes a colour change in response to laser irradiation at a wavelength above 2000 nm but not between 700-2000 nm, and the metal salt absorbs laser radiation at 700-2000 nm thereby causing the marking component to change colour wherein said method further comprises irradiating the formulation with a laser.