Abstract: To prevent unauthorized duplication of important security documents, an improvement in security or protected documents is disclosed. The security document includes a substrate having top and bottom surfaces where at least one of the surfaces is adapted to carry printed copy thereon. A colored background is printed on at least a portion of one of the surfaces, such as the surface which is adapted to carry printed copy, using a temperature sensitive ink. The security document also includes copy printed on at least a portion of the one of the surfaces adapted to carry printed copy thereon. With these features of construction, the security or protected document contemplates the copy being printed by utilizing a temperature insensitive ink.