“Heat Sensitive Camouflaged Message”
U.S. Patent 5,873,604 – 6,396,927 – 5,636,874, 5,695,220
G.B. Patent 2,276,588 B
Brisk and rapid rubbing of the indicia areas reveals a hidden valid alert message and verifies authenticity. Additionally, the heat from a color copier will normally activate the hidden alert message causing the accepting party to read the warning message. The activated message reverts back to its camouflaged effect upon cooling.
Normal Room Temperature 74°
Fully Activated at 100°