| 摘要 |
A method and system sor securing a substrate such as paper and the like against counterfeiting, photocopying, and facsimile transmission and an applicator and paper for use in the method and system and with the applicator. The method and system comprise providing a substrate having a background color on one surface thereof, covering at least one selected area of the surface with one of a colorless color developer and a colorless color former dye, wherein the color developer and color former dye react when mixed to produce a first given color which is different from the background color and applying the other of the colorless color developer and the colorless color former dye to at least a portion of the at least one selected area to change the background color to said first given color. |
