Seen It a Million Times
. Also, Truth in Television
: it was a valid secret communication technique right until early XX century, when UV lamps (aka "Wood's Light", "black light") killed it.
Usually done with heat-sensitive inks once used in Real Life
, though occasionally Utility Magic
reproduces the effect.
Anime and Manga
- In Speed Racer Pops has put the blueprints to the Mach 5 in invisible ink on the windshield of the car.
- Keroro Gunsou has a chapter where he receives a message from his superiors that had to be revealed by rubbing an eraser on it. In the anime, the message also gets partially revealed due to entry through the atmosphere.
- In Ouran High School Host Club Tamaki's father sends him messages in invisible ink (made with lemon juice). The club believes that the messages come from the person sending them threatening letters and hilarity ensues.
- Gone In Sixty Seconds. Memphis (Nicolas Cage) and his crew use this to hide a list of target cars, from Detective Castlebeck. The writing is only visible under "black light".
- Who Framed Roger Rabbit. Mr. Acme was the inventor of the 'disappearing-reappearing ink' , which would become invisible almost immediately, but become visible again through time, and wrote his will with it, leading it to be believed lost.
- National Treasure: A secret message was written on the Declaration of Independence with invisible ink that was revealed with heat.
- Two short stories by Agatha Christie (one featuring Hercule Poirot and one Miss Marple), involve rich eccentrics writing their will in Invisible Ink, and challenging the heirs to find it.
- Encyclopedia Brown had a story which used lemon juice as the ink of choice.
- In Edgar Allan Poe's "The Gold Bug", the whole plot is triggered by a piece of parchment being accidentally held near a fire long enough to bring out a message in invisible ink.
- In Tolkien's Legendarium, there are several kinds of magical invisible writing. First is called "moon letters" and is written with silver pens and unknown ink that is only visible in moonlight. Second (not quite an ink but similar) is ithildin, a metal alloy that only reflects starlight and moonlight when certain magical spells are recited, and is normally transparent, used to decorate the Gates of Moria which blend seamlessly with rock. Revealing ithildin is the only way to see these gates.
- In Raumschiff GameStar, the employee contract clause that forces all crew members (except The Captain and the medical officer) to wear bright orange overalls is printed in ink that is only visible if you hold the paper against the light of a full moon on a certain date and day of the week.
- In the Bones Season 7 finale a man in a mental institution leaves a secret message written on the walls in his own saliva. It works like invisible ink; it only shows up under special light.
- On the Back Door Pilot for The Finder on Bones, the treasure map has writing that can only be revealed with blood.
- Dungeons & Dragons
- The Book of Marvelous Magic has Inkwell of Concealment, which is an Everfull Inkwell, but after a hour everything written with its ink vanishes and can be read only via effects allowing to see invisible objects.
- Tolkien's version above was thrown in when sourcebook Player's Options: Spells & Magic introduced 'Moon Rune' spell that displays letters when its triggering condition is met, including moonlight in the proper phase or presence of creatures (set by species).
- My Little Pony: Friendship Is Magic: As a practical joke, Pinkie Pie and Rainbow Dash replaces Twilight Sparkle's ink with invisible ink. Twilight eventually did the same thing to Princess Celestia.
- In Avatar: The Last Airbender Zuko received a note with a secret message written in invisible ink which was revealed with heat.