Abstract: An envelope with a pressure sensitive seal containing a hidden printed message which is revealed when the seal has been opened. The unsealed edges of the envelope each have an anchor coating, and the message is formed by voids in the anchor coating on one edge. Cohesive layers adhere to the anchor coatings on both edges, and seal the envelope as desired. The cohesive layers have a stronger affinity for each other than for the anchor coating with the void regions, and so the message is revealed as the cohesive layer separates from the void-containing anchor coating when the sealed envelope is opened.

Abstract: An envelope with a pressure sensitive seal containing a hidden printed message which is revealed when the seal has been opened. The unsealed edges of the envelope each have an anchor coating covered by a cohesive layer. The message is formed by voids in the cohesive layer on one edge. Cohesive layers adhere to the anchor coatings on both edges, and seal the envelope as desired. The cohesive layers have a stronger affinity for each other than for the anchor coating. The message is revealed as the cohesive layer containing voids separates from the anchor coating causing the disruption of the anchor coating, when the sealed envelope is opened.