A SECURITY MARKING METHOD AND COMPOSITION
A security marking method and composition as shown in Figs. 1-3, wherein a first marking (2) is applied to a surface of a substrate (1) with a mixture of a printing medium and a first composition, wherein the first marking is visible to an unaided human eye and is indistinguishable from a marking applied with the printing medium alone, to an unaided human eye when illuminated by visible light or ultraviolet light (4). A second composition (3) is added either with the mixture or thereafter, wherein the second composition is reactable with the first composition to fluoresce (2a) and wherein the fluorescing is only visible to an unaided human eye when illuminated by ultraviolet light (4).