A security marking method and composition

摘要

A security marking method comprises marking a portion of the substrate by applying a first marking fluid which is invisible to a unaided eye when illuminated by both visible light and ultraviolet light and activating the marked portion by applying a second marking fluid thereon. The second marking fluid is reactable with the first marking fluid to be invisible to an unaided human eye when illuminated by visible light and fluorescent when illuminated by ultraviolet light. The invention also includes the composition comprising the first and second marking fluids.