Patent ID: 7350687

Claim:
A tamper resistant envelope comprising: a first panel with an interior and an exterior side; a second panel attached to the first panel to define an interior portion having opposite side edges, a closed edge portion and an opening portion opposite the closed edge portion to provide access to the interior portion of the tamper resistant envelope; and a flap for sealingly adhering to an exterior surface of the first panel, the flap having an interior and an exterior side and attached to the second panel at an edge of the second panel opposite the closed edge portion, the flap comprising thereon: a first adhesive layer on the interior side of the flap comprising a first remoistenable adhesive deposited on the flap; a solid dye deposited on a portion of the first adhesive layer, wherein the dye is not visible on the exterior side of the flap; and a second adhesive layer comprising a second remoistenable adhesive deposited over the dye to encapsulate the dye, wherein the dye is capable of being released upon contact with steam to provide a visual indication of the dye and an indication of tampering.