The voter marks the location using a specially provided decoder pen, which activates the invisible ink causing it to darken, revealing a confirmation code.
The fifty euro note contains several complex security features such as watermarks, invisible ink, holograms and microprinting that document its authenticity.
The euro notes contain many complex security features such as watermarks, invisible ink, holograms and microprinting that document their authenticity.
The injury was followed by damage to the right eye as a result of using invisible ink.
Very rarely, invisible ink has been used in art.
Invisible ink is one form of steganography, and it has been used in espionage.
She was interested in musical codes and invisible ink.
Were they in invisible ink?
