Tamper-indicating and authenticating label

Abstract

A tamper-indicating and authenticating label which provides a temporary visually perceptible indication that the label is authentic, and provides a permanent indication of tampering with the label. The label comprises a normally opaque microporous film which becomes substantially transparent upon application of a suitable liquid. The label includes tamper-indicating and authenticating indicia which are normally not visually perceptible when the microporous film is opaque, and which become visible when the microporous film is made transparent. The authenticating indicia is made temporarily visible to authenticate the label by applying a volatile liquid to the film to render it transparent, without dissolving the tamper-indicating indicia. Application of solvents in an attempt to defeat the adhesive of the label will cause the tamper-indicating indicia to bleed through to the surface of the label, providing a permanent indication of tampering. Application of high temperature in an attempt to defeat the adhesive of the label will collapse the microvoids of the film, permanently transparentizing the film and causing the tamper-indicating indicia be permanently visible. Application of oil in an attempt to defeat the adhesive of the label will permanently transparentizing the film and cause the tamper-indicating indicia be permanently visible. The microporous film can either be stretchy and permanently deformable, or brittle and easy to tear or break, to provide additional permanent indication of tampering.