Geek Trivia

The Security Feature Wherein “VOID” Appears On Photocopied Documents Is Called A?

Refractory
Copyblock
Pantograph
Photobar
Which Of These Products Did Microsoft Design But Then Deny, Claiming It Was A Hoax?

Answer: Pantograph

Many documents contain a hidden message that only appears when photocopied. This message, found on checks, birth certificates, prescription slips, and other documents prone to fraudulent reproduction is known in the printing industry as a “void pantograph”. It is named such as the most commonly used word is “VOID” and the term pantograph is a Greek term that means copy writing.

While the methods by which void pantographs are created vary, some printers use off-set patterns of tiny perpendicular lines while others use tiny dots; the mechanism of action relies on the limitations of the photocopying process. While photocopiers do a pretty great job of making copies of simple text and even photographs, they function as a type of low-pass filter for certain patterns. When you make a copy of the security-marked document, the invisible-to-the-human-eye words appear clearly in the copy.