Abstract: A method and compositions for authenticating a document or article comprises applying a mixture of a carrier, a leuco dye and an activator to a surface of a document or article, wherein the leuco dye and activator react in response to a rubbing force applied to the surface to change color and wherein the activator is at least one selected from the group consisting of amidophenol, anilides with hydroxyl groups and benzoamides with hydroxyl groups and authenticating the document or article by applying a rubbing force to the surface to effect a color change.

Abstract: A security marking method and composition wherein a first marking is applied to a surface of a substrate 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. A second composition is added either with the mixture or thereafter, wherein the second composition is reactable with the first composition to fluoresce and wherein the fluorescing is only visible to an unaided human eye when illuminated by ultraviolet light.

Abstract: A latent image printing method and apparatus uses a substrate with one main surface having a covering comprising only one of a first pair of a color developer and color former dye in at least one selected latent imaging area defining a background color in conjunction with the one main surface, wherein the color developer and the color former dye react when mixed to produce a first spectral response which is visible relative to the background color and a continuous coating over the covering which is non-porous with respect to the other of the pair and solvent-resistant to the other of the pair. The coating above selected portions of the covering corresponding to a desired latent image is removed.

Abstract: 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.

Abstract: A method for protecting against duplication of a document with a color copier comprises providing a background color on a document having an average reflectance value and printing on the background with a contrast color having a spectral characteristic which modulates the average reflectance value by no more than 5% and has an average value equal to the average reflectance value. The contrast color is printed with a printing medium that allows activation by a rub and reveal action or by application of intense light.