IR Absorbent and IR Reflective Ink

These are specialized inks that can absorb or reflect infrared light, often used to hide a message, symbol or graphic, such as a bar code, within a document. The desired message is printed with infrared absorbent ink while a black box covering the message is overprinted in infrared reflective ink, effectively hiding the message from visual observation. With the use of an infrared light source and filter, the infrared absorbent ink becomes visible while the infrared reflective ink disappears.