Apparatus for visually indicating elapsed time by a color change

摘要

Apparatus for visually indicating elapsed time by a color change is disclosed comprising a first and second chromophoric compound that are combined with one another through a matrix which controls the rate of combination of the compounds so that a color body is produced by the reaction of the compounds over a period of time that may be adjustable from anywhere from about one to about thirty days. The device comprises a transparent container having a rupturable capsule therein in which the first composition is contained. A transparent matrix surrounding the second composition is also in the container. The device may be secured to a surface by means of a mechanical fastener or an adhesive layer.