Created By: TBeholderMay 21, 2012 Last Edited By: morenohijazoDecember 27, 2015
Troped

Invisible Writing

Something is written here, but you won\'t see it if you don\'t know how to reveal it

Name Space:
Main
Page Type:
Trope
DAN 004 wuz ere takin over ur druft


Describe Invisible Writing here.

Something that looks innocuous and featureless actually has some writing on it. You aren't able to see it with the naked eye: you'll need some way to reveal it.

A simple example is writing a messsage with citrus juice. Once it dries, the print becomes invisible. One must warm the paper to reveal the words. Other times, you will need specialized equipment such as a fluoroscope or a chromatic filter to view the writing. In fantasy worlds, magic or Green Rocks are needed to make the writing visible. Possibly, the writing can only be read by a specific person, or at a specific time frame or location. Otherwise, the writing is invisible.

As with any secret message, this is done so the message can't be read by just anyone, and can easily be overlooked during a search.

May lead to Fridge Logic: if one uses an "invisible ink" to write, wouldn't the writer have a hard time writing it? (It may be handwaved by turning the text invisible after it was written, in some way.)

Truth In Television: this was a valid secret communication technique right until the 20th century, when UV lamps (a/k/a "Wood's Light", "black light") rendered it obsolete.

Condensation Clue is a subtrope. See also See The Invisible on ways to make things visible.


Examples:

    open/close all folders 

    Advertising 
  • A few breakfast cereals during The Seventies would print trite messages on the boxes, disguised as random dopplings of color. A piece of tinted cellulose, usually red, was used to screen out the "noise" colors, leaving the remainder to form legible print.

    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.
  • In Naruto, the Uchiha tablet on first glance gives the basic informations regarding secrets of the Uchihas. But use your Mangekyou Sharingan or Rinnegan and you will see even more details regarding the history of the ninja world. Such as the history of Senju and Uchiha war and the origin of the Ten-tails.

    Film 
  • 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. Mr. Acme also 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. Further clues were embedded in the Declaration of Independence, visible only through a pair of glasses with switchable chromatic filters.
  • In Now You See Me, the Horsemen's New Orleans show seems to use some form of Invisible Ink which shows up under a flashlight.
  • Constantine: Angela and her sister Isabela left hidden messages on windows and mirrors when they were kids, visible only when fogged by their breath. Isabela left her sister one last message before she was Driven To Suicide.

    Literature 
  • 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 Tolkiens 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. In The Hobbit, Thorin's map to Erebor has such invisible script. 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.
    • Bilbo Baggins's magic ring seemed ordinary enough, with nothing apparent on its inner surface. However, once Gandalf the Grey threw that ring into the hearth fire and later retrieved it, it's fateful inscription appeared: "One Ring to rule them all ..."
  • In Harry Potter And The Chamber Of Secrets, the team initially thinks that Tom Riddle's diary was written with invisible ink, with Hermione trying spells and a magicked eraser called a "revealer" to try and make something visible. Subverted: The diary contains Tom Riddle's memories in a very literal sense, and is capable of responding to written messages.
    • In The Prisoner of Azkaban, Fred and George introduced the Marauder's Map, which doesn't just show the map of whichever building the holder is in, but also shows the footsteps of people. It looks like just an empty sheet of old paper... unless you know the chant for activating it.
  • James Bond in On Her Majestys Secret Service uses his urine ("the oldest [secret ink] in the world") to write down the names of the allergy treatment patients in Piz Gloria, before he tries to make his escape from the place.
  • Briefly appears in one of the Deltora Quest books, Isle of the Dead. Tom the shopkeeper sends Lief, Barda and Jasmine a gift of firebeads and sweets. Since Tom is notorious for his No Hero Discount attitude they are wondering why he did so, when they notice that the wrapping they had left by the fire they just made now has writing on it. The wrapping is a note from Tom advising them on the next stage of their quest... with a postscript asking them, when convenient, to pay for the items he has sent.
  • In In the King's Service, Alyce de Corwyn gets a letter from her late father that appears to have a banal message about a bequest of family jewels, yet he left a second message revealing that Vera Howard is really Alyce's twin sister that only becomes visible when Alyce activates her father's spell by kissing the wax seal.
  • Mortally wounded curator Jacques Sauniere leaves an important clue scrawled on the Louvre's parquet floor, that can only be seen under ultraviolet light, in The Da Vinci Code. "O Draconian Devil / Oh Lame Saint." It was made not to implicate his killer, but rather to indicate his killer's objective.
  • One of the Billy Bunter stories had a main character receive a letter from a missing relative, asking whether he remembered a particular party trick. He doesn't, but the letter is left out in the hot sun for a while, which reveals the real message saying that the relative has been kidnapped.
  • In Aunt Dimity and the Lost Prince, young neighbour Bree Pym shows Lori's young twins how to write invisibly with lemon juice and reveal the messages with the heat of a lightbulb. It's part of her unexpected arsenal of talents for entertaining kids, a bag of tricks that includes juggling, acrobatics, yoga and sleight-of-hand magic.
  • Two Agatha Christie short stories, one featuring Hercule Poirot and one Miss Marple, involve rich eccentrics writing their will in Invisible Ink, and challenging the heirs to find it.
  • The Count Of Monte Cristo: the key to the colossal fortune was found in an old piece of paper used as a bookmark. When Faria tried to use it to light a candle, he noticed words forming on it and quickly extinguished it, but was arrested before he could find it.
  • Discworld:
    • Parodied in the book Witches Abroad. The witches come upon a dwarf mine, identified by invisible runes. Magrat states she can't see them, which Nanny Ogg points out is how you know you got your money's worth with invisible runes.
    • Also, the Unseen University faculty includes the Reader in Invisible Writings.
  • The bracelet given to apprentice white witch Susan, in Alan Garner's fantasy novel The Moon of Gomrath, is apparently of plain silver with nondescript black inlay. But in times of great need, it manifests readable writing, which when spoken by her becomes a spell of great potency and confounds the creations of evil.

    Live Action TV 
  • 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.
  • One of the things Abraham Woodhull does as part of his spy work for George Washington in Turn is transmit messages via invisible ink that requires the application of a coat of "reagent" for the message to be visible.
  • An episode of Hetty Feather has a new Foundling (Eliza) arrive at the hospital and it turns out she stayed with the same foster family as Hetty. Hetty learns from Eliza that her foster brother mentioned the secret squirrel house they used to play at and that her foster brother did not mention Hetty to Eliza at all, leading Hetty to think that he has forgotten about her. When Hetty's friends learn of this, they have Eliza write a letter home, with the line "I hope you are reading this by your lovely warm fire" and on Eliza's letter, they write a message using lemon juice, which won't show up on the paper unless it is held up to a fire, to tell the foster brother what has happened to Hetty.
  • Arrow:
    • One episode has the names of Starling City's most corrupt criminals written in a handbook owned by Oliver's father. He only realized it wasn't blank when he put it near a flame and the names came up. The ink can also be revealed by way of a special pair of glasses.
    • The team finds some notes written the same way in Sara's boot in "The Magician" episode. Nyssa calls it "Ghost Ink" and says it is one of the standard methods that the League of Assassins employ for concealing secrets.
  • In one episode of The Office, Dwight attempts to pass a secret message to the other salespeople by handing them letters with a second message written beneath the main text in invisible ink, hinting to them to expose the letters to heat to make the secret message visible. Of course, none of them bothers to do so. Dwight also cheerfully admits that the "invisible ink" in question is in fact his own urine.
  • In House Of Anubis, Sibuna find an old dictionary but when they open it, nothing is written in it. Later it turns out the text was in invisible ink, and the heat from the flashlight made the words appear.
  • Three Two One Contact's "Bloodhound Gang" has a story called "The Case of the Secret Message" in which they find an old lady's stolen purse and finds that it only has a seemingly blank piece of paper. The Gang suspects invisible ink, but have to go through various methods to find out like heating it to expose lemon juice writing, which doesn't work. Eventually, the way to expose the writing is it to rub pencil graphite on the paper to expose the secret writing that was written in salt water.
  • Elementary: When Sherlock and Joan retrieve the Body Of The Week of the "Art in the Blood" episode for an autopsy, they are more than a little surprised to find that his apparently ordinary arms had been stolen and nothing else. After some investigation they find out that his ex-wife is a tattoo artist and he had her cover his arms with tattoos that only show up under UV light.
  • Blindspot: Jane Doe's body is already covered in tattoos that contain hidden meanings but in the "Bone May Rot" episode, it is discovered that she also has tattoos that are only appear under the exact frequency of UV light that used for decontamination at the CDC.

    Tabletop Game 

    Video Games 
  • In the Assassins Creed series, many instances exist of characters using Eagle Vision in order to see hidden messages.
  • In Dark Fall The Journal, the picture of a pigeon can be heated over the gas stove upstairs, causing the names of four Lyrics to appear.
  • In the video game The Riddle Of The Sphinx, holding a sheet of paper over the candle in the tent lets you see a secret message in it.
  • In the Nancy Drew game The Haunted Carousal; she helps out the bookkeeper with some puzzles that would reconnect her childhood (long story). One puzzle involved a piece of lemon scented paper that showed a message when ironed.
  • Alone In The Dark 3: At one point, while exploring the town hall, you find an apparently blank book. Another tips you of its true nature and what to do with it: reading in while standing near a light candle will reveal it's actually a book written by Pregtz, the Big Bad from the first game.

    Western Animation 
  • 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.
  • In the second season of Gravity Falls, Dipper discovers that the Journals have additional writing in invisible ink made visible through a black light.
  • In an early episode of Rocky And Bullwinkle Natasha reveals a message that was in invisible ink by holding the paper in front of a candle: "Keel Moose." Boris drops a safe to land on Bullwinkle's head. After the Commercial Break Cliffhanger Natasha says that two more words have appeared: "Do Not." Boris races the safe to save Bullwinkle.
  • This was also used in the Garfield And Friends episode "The Legend Of Long Jon". Garfield and Odie were reading from the journal of Jon's pirate ancestor Long Jon Arbuckle, when Odie started drooling on an apparently blank page, which causes writing to appear on the page. It turned out that Long Jon Arbuckle had written on the blank pages in invisible ink, telling about how he was able arrest some bandits that were carrying phony documents.
  • Cale Tucker, The Hero of Don Bluth's Titan AE, receives a ring from Captain Korso. The ring has been coded to Cale's genetics so that it reveals a star map on Cale's hand. As a further safeguard, the map's pointer shifts direction while Cale is standing on a platform on Sessarim.

    Real Life 
  • One poor unfortunate decided to rob a bank and his "disguise" was lemon juice on his face, thinking that per its use as invisible ink it would keep the security cameras from recording him. He was wrong.
  • The idea of using citrus oils as in National Treasure was a common means of sending covert messages through the end of the Cold War. While an oven was required to reveal the message in National Treasure, an ordinary incandescent light bulb is usually enough to reveal such messages.
  • A really Squicky example: fresh male sperm may be used as an invisible ink much as lemon juice may be applied. apparently all men can access a stock even if in a place where no lemons are available.

Community Feedback Replies: 108
  • May 21, 2012
    Koveras
    • 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.
  • May 21, 2012
    randomsurfer
    • 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.
    • I'm pretty sure there was an Encyclopedia Brown story which used lemon juice as the ink of choice, but I don't recall now which one.
  • May 21, 2012
    WackyMeetsPractical
    • 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.
    • 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.
    • National Treasure: A secret message was written on the Declaration of Independence with invisible ink that was revealed with heat.
  • May 21, 2012
    Antigone3
    In 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.
  • May 21, 2012
    reub2000
  • May 21, 2012
    animeg3282
    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.
  • May 21, 2012
    Dacilriel
    In Avatar The Last Airbender Zuko received a note with a secret message written in invisible ink which was revealed with heat.
  • May 23, 2012
    aurora369
    In JRR Tolkien's verse, 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.
  • May 29, 2012
    TBeholder
    ^ Tolkien's version was thrown in Dungeons And Dragons - AD&D2 sourcebook Tome of Magic introduced "Moon Runes" spell, displaying letters when the triggering condition is met, including moonlight in the proper phase or presence of creatures (set by species).
  • May 29, 2012
    HumanaUox
    The end of that Roger Rabbit example should be a spoiler.
  • July 17, 2012
    MiinU

    Film

  • July 19, 2012
    MiinU
    bump.
  • July 19, 2012
    randomsurfer
    In an episode (the first??) of Speed Racer Pops has put the blueprints to the Mach 5 in invisible ink on the windshield of the car.
  • July 20, 2012
    triassicranger
    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.
  • July 20, 2012
    DaibhidC
  • September 11, 2012
    TBeholder
  • September 11, 2012
    captainsandwich
    Dungeons And Dragons book Dungeonscape has an item that is functionally invisible ink (although it can be seen with a very high DC spot/search check (don't remember which). Then again, you can see some invisible ink if you look closely (good vision may be required), or at least a side effect of the ink, like an imprint on the paper or something.
  • September 11, 2012
    captainsandwich
    the spell Dungeons And Dragons spell Arcane Mark can functionally be an invisible ink. The campaign setting Eberron notices this, and uses it on documents to increase the difficulty of forging.
  • September 14, 2012
    LadyJuse
    In the Nancy Drew game The Haunted Carousal; she helps out the bookkeeper with some puzzles that would reconnect her childhood (long story). One puzzle involved a piece of lemon scented paper that showed a message when ironed.
  • December 18, 2012
    Azaram
    The D&D example is older than you think. Moon runes were in the original first edition Player's Handbook.
  • May 10, 2013
    AFP
    Another film example:

    • Constantine: Angela and her sister Isabela left hidden messages on windows and mirrors when they were kids, visible only when fogged by their breath. Isabela left her sister one last message before she was Driven To Suicide.
  • July 9, 2013
    69BookWorM69
    New Literature example:
    • In Aunt Dimity and the Lost Prince, young neighbour Bree Pym shows Lori's young twins how to write invisibly with lemon juice and reveal the messages with the heat of a lightbulb. It's part of her unexpected arsenal of talents for entertaining kids, a bag of tricks that includes juggling, acrobatics, yoga and sleight-of-hand magic.
  • July 10, 2013
    Melkior
    Literature:

    • One of the Billy Bunter stories had a main character receive a letter from a missing relative, asking whether he remembered a particular party trick. He doesn't, but the letter is left out in the hot sun for a while, which reveals the real message saying that the relative has been kidnapped.
  • July 10, 2013
    Melkior
    It may help to mention that lemon juice works as a real life invisible ink, with heat revealing the message by cooking the juice which turns it brown.
  • July 10, 2013
    Arivne
    Namespaced and italicized work titles, sorted examples by media type.
  • July 10, 2013
    SharleeD
    • In Dark Fall The Journal, the picture of a pigeon can be heated over the gas stove upstairs, causing the names of four Lyrics to appear.
    • In the video game The Riddle Of The Sphinx, holding a sheet of paper over the candle in the tent lets you see a secret message in it.
  • July 15, 2013
    69BookWorM69
    I think the description needs a bit of help, maybe a sentence or two.
  • July 15, 2013
    Paradisesnake
    Did some formatting.
  • July 15, 2013
    oneuglybunny
    Literature
    • Mortally wounded curator Jacques Sauniere leaves an important clue scrawled on the Louvre's parquet floor, that can only be seen under ultraviolet light, in The Da Vinci Code. "O Draconian Devil / Oh Lame Saint." It was made not to implicate his killer, but rather to indicate his killer's objective.
  • July 16, 2013
    CaveCat
    • This was also used in the Garfield And Friends episode "The Legend Of Long Jon". Garfield and Odie were reading from the journal of Jon's pirate ancestor Long Jon Arbuckle, when Odie started drooling on an apparently blank page, which causes writing to appear on the page. It turned out that Long Jon Arbuckle had written on the blank pages in invisible ink, telling about how he was able arrest some bandits that were carrying phony documents.
  • July 16, 2013
    oneuglybunny
    Add one more to the JRR Tolkien entry:

    Literature
    • Bilbo Baggins's magic ring seemed ordinary enough, with nothing apparent on its inner surface. However, once Gandalf the Grey threw that ring into the hearth fire and later retrieved it, it's fateful inscription appeared: "One Ring to rule them all ..."
  • July 16, 2013
    69BookWorM69
    This trope is Exactly What It Says On The Tin.

    Question; Would this count? In In the King's Service, Alyce de Corwyn gets a letter from her late father that appears to have a banal message about a bequest of family jewels, yet he left a second message revealing that Vera Howard is really Alyce's twin sister that only becomes visible when Alyce activates her father's spell by kissing the wax seal.
  • July 20, 2013
    randomsurfer
    There should be a Self Demonstrating Article version which is entirely spoilered out.
  • July 20, 2013
    Sibuna
    • In House Of Anubis, Sibuna find an old dictionary but when they open it, nothing is written in it. Later it turns out the text was in invisible ink, and the heat from the flashlight made the words appear.
  • July 20, 2013
    DAN004
    ^^ Do want.
  • July 20, 2013
    69BookWorM69
    ^^ Seconded! That would be good.
  • July 20, 2013
    Sibuna
    ^^^ Agreed
  • July 21, 2013
    Arivne
    Would this include:

    • Disappearing Ink: When it's first written it can be read, but disappears a short time later?
      • Example: Animated film Gay Purree. Meowrice writes a check to Madame Henretta Reubens-Chatte but the ink on the check disappears later.
    • Disappearing-Reappearing Ink as in the Who Framed Roger Rabbit example?

    If they are part of the trope, the description should be changed to allow them.
  • July 21, 2013
    MattStriker
    • In Now You See Me, the Horsemen's New Orleans show seems to use some form of Invisible Ink which shows up under a flashlight.
  • July 21, 2013
    69BookWorM69
    Just watched the first season of Miss Fisher's Mysteries (based on the books about 1920s detective Phryne Fisher, and one of the episodes (apparently based on the book Raisins and Almonds) had invisible ink used to conceal a chemical formula for artificial rubber. Has anybody read the book to know if the same thing happened in it?
  • November 12, 2013
    sandangel
    [[Series/Arrow]]: While on the island, Oliver's father's list is revealed when he holds it near a fire.
  • November 12, 2013
    Bibliophile
    Briefly appears in one of the Deltora Quest books, Isle of the Dead. Tom the shopkeeper sends Lief, Barda and Jasmine a gift of firebeads and sweets. Since Tom is notorious for his No Hero Discount attitude they are wondering why he did so, when they notice that the wrapping they had left by the fire they just made now has writing on it. The wrapping is a note from Tom advising them on the next stage of their quest... with a postscript asking them, when convenient, to pay for the items he has sent.
  • May 13, 2014
    erforce
    Literature
    • James Bond in On Her Majestys Secret Service uses his urine ("the oldest [secret ink] in the world") to write down the names of the allergy treatment patients in Piz Gloria, before he tries to make his escape from the place.
  • May 14, 2014
    Folamh3
    • In one episode of The Office, Dwight attempts to pass a secret message to the other salespeople by handing them letters with a second message written beneath the main text in invisible ink, hinting to them to expose the letters to heat to make the secret message visible. Of course, none of them bothers to do so. Dwight also cheerfully admits that the "invisible ink" in question is in fact his own urine.
  • May 14, 2014
    Arivne
    Blue Linked Examples media section titles(s).
  • May 15, 2014
    Synchronicity
    • Arrow has the names of Starling City's most corrupt criminals written in a handbook owned by Oliver's father. He only realized it wasn't blank when he put it near a flame and the names came up. The ink can also be revealed by way of a special pair of glasses.
  • May 15, 2014
    Notthegrouch
    Does Harry Potters Marauders map count?
  • May 20, 2014
    randomsurfer
    In an early episode of Rocky And Bullwinkle Natasha reveals a message that was in invisible ink by holding the paper in front of a candle: "Keel Moose." Boris drops a safe to land on Bullwinkle's head. After the Commercial Break Cliffhanger Natasha says that two more words have appeared: "Do Not." Boris races the safe to save Bullwinkle.
  • May 21, 2014
    DAN004
    ^^ Kinda not sure.
  • May 21, 2014
    acrobox
    Naruto: In the Naka Shrine there's a stone monument which contains the Uchiha clan's secrets. The catch is it can only be read with the Uchiha's special eye techniques. The Rinnegan is able to completely decipher the contents of the monument, while the Sharingan and Mangekyo Sharingan are only able to partially decipher it. It's otherwise unknowable to outsiders and Uchiha's who haven't unlocked their eye's potential.
  • March 21, 2015
    DAN004
    Bump?
  • June 23, 2015
    eroock
    Bump
  • June 25, 2015
    triassicranger
    I don't know if the original book did this.

    Live Action Television
    • An episode of Hetty Feather has a new Foundling (Eliza) arrive at the hospital and it turns out she stayed with the same foster family as Hetty. Hetty learns from Eliza that her foster brother mentioned the secret squirrel house they used to play at and that her foster brother did not mention Hetty to Eliza at all, leading Hetty to think that he has forgotten about her. When Hetty's friends learn of this, they have Eliza write a letter home, with the line "I hope you are reading this by your lovely warm fire" and on Eliza's letter, they write a message using lemon juice, which won't show up on the paper unless it is held up to a fire, to tell the foster brother what has happened to Hetty.
  • June 25, 2015
    gallium
    Live-Action TV

    • One of the things Abraham Woodhull does as part of his spy work for George Washington in Turn is transmit messages via invisible ink that requires the application of a coat of "reagent" for the message to be visible.
  • June 25, 2015
    StarSword
    Literature:
    • In Harry Potter And The Chamber Of Secrets, the team initially thinks that Tom Riddle's diary was written with invisible ink, with Hermione trying spells and a magicked eraser called a "revealer" to try and make something visible. Subverted: The diary contains Tom Riddle's memories in a very literal sense, and is capable of responding to written messages.
  • June 25, 2015
    gallium
    "right until early XX century"—this in the intro should read "right until the early 20th century"
  • June 25, 2015
    SolipSchism
    Just dropping in to point out that oneuglybunny added another, more well-known, example from LOTR (the inscription on the Ring that is only revealed by fire). Looks like it's been overlooked.
  • August 30, 2015
    pvsage
    Real Life:
    • The idea of using citrus oils as in National Treasure was a common means of sending covert messages through the end of the Cold War. While an oven was required to reveal the message in National Treasure, an ordinary incandescent light bulb is usually enough to reveal such messages.
  • August 30, 2015
    gallium
    Add all the examples and I'll add the fifth hat.
  • August 30, 2015
    shimaspawn
    ^ You're free to add them yourself.
  • August 30, 2015
    oneuglybunny
    Oh, let me add to the National Treasure example that further clues were embedded in the Declaration of Independence, visible only through a pair of glasses with switchable chromatic filters.
  • August 31, 2015
    randomsurfer
    Real Life: One poor unfortunate decided to rob a bank and his "disguise" was lemon juice on his face, thinking that per its use as invisible ink it would keep the security cameras from recording him. He was wrong.
  • October 23, 2015
    eroock
  • October 31, 2015
    rmctagg09
    • In the Assassins Creed series, many instances exist of characters using Eagle Vision in order to see hidden messages.
  • October 31, 2015
    Loekman3
    • In Naruto, the Uchiha tablet on first glance gives the basic informations regarding secrets of the Uchihas. But use your Mangekyou or Rinnegan and you will see even more details regarding the history of the ninja world. Such as the history of Senju and Uchiha war and the origin of the Ten-tails.
  • October 31, 2015
    DAN004
    If nobody ever updates this, I'll grab it.
  • November 1, 2015
    TonyG
    In the second season of Gravity Falls, Dipper discovers that the Journals have additional writing in invisible ink made visible through a black light.
  • November 1, 2015
    DAN004
    EDIT: NVM
  • November 7, 2015
    kchishol
    Three Two One Contact's "Bloodhound Gang" has a story called "The Case of the Secret Message" in which they find an old lady's stolen purse and finds that it only has a seemingly blank piece of paper. The Gang suspects invisible ink, but have to go through various methods to find out like heating it to expose lemon juice writing, which doesn't work. Eventually, the way to expose the writing is it to rub pencil graphite on the paper to expose the secret writing that was written in salt water.
  • November 7, 2015
    NateTheGreat
    Don't forget that in National Treasure if you covered the entire back with lemon juice and then "triggered" the invisible ink reaction with heat, all you'd get is a smear of brown. Lemon juice doesn't reveal invisible ink, it is invisible ink.
  • November 8, 2015
    DAN004
    Yo, what else does this need?
  • December 7, 2015
    eroock
    Hats!
  • December 7, 2015
    DAN004
    Keep 'em coming, people.
  • December 7, 2015
    Chabal2
    The Count Of Monte Cristo: the key to the colossal fortune was found in an old piece of paper used as a bookmark. When Faria tried to use it to light a candle, he noticed words forming on it and quickly extinguished it, but was arrested before he could find it.
  • December 10, 2015
    morenohijazo
    • Alone In The Dark 3: At one point, while exploring the town hall, you find an apparently blank book. Another tips you of its true nature and what to do with it: reading in while standing near a light candle will reveal it's actually a book written by Pregtz, the Big Bad from the first game.
  • December 11, 2015
    NoirGrimoir
    • In both the book and film version of The Hobbit, Thorin's map, which holds the secret to sneaking into the Lonely Mountain, contains "Moon Runes" which can only be seen under the light of the same moon under which they were written and are otherwise invisible.
  • December 11, 2015
    ZuTheSkunk
    What about invisible ink that can literally turn anyone invisible? I remember a Tom & Jerry episode that was centered around it.
  • December 11, 2015
    DAN004
    ^^ The moon runes thing is already there in Tolkien's Legendarium. I still added the Hobbit part though.

    ^ I think it's a different trope... (In fact we may have that one already, although I forgot the name)

    Just realized that the focus is more on the invisible words rather than the ink, cuz Tolkien's Legendarium has non-ink examples.
  • December 11, 2015
    NoirGrimoir
    I think ink that turns someone invisible (assuming that it's primarily used for writing) or say ink that is just plain invisible in the jar are versions of Playing With the trope.
  • December 16, 2015
    Arivne
    ^^^ ^^ ^

    The substance that turns people invisible when you pour/rub it on them was proposed on YKTTW as Vanishing Cream.
  • December 16, 2015
    DAN004
    Great, now I'm rewriting this trope.
  • December 17, 2015
    gallium
    ^Why? Launch.
  • December 17, 2015
    DAN004
    Gotta wait for a few more examples...
  • December 17, 2015
    eroock
    Condensation Clue is a subtrope.
  • December 17, 2015
    AgProv
    Literature
    • The bracelet given to apprentice white witch Susan, in Alan Garner's fantasy novel The Moon of Gomrath, is apparently of plain silver with nondescript black inlay. But in times of great need, it manifests readable writing, which when spoken by her becomes a spell of great potency and confounds the creations of evil.
  • December 18, 2015
    oneuglybunny
    Western Animation
    • Cale Tucker, The Hero of Don Bluth's Titan AE, receives a ring from Captain Korso. The ring has been coded to Cale's genetics so that it reveals a star map on Cale's hand. As a further safeguard, the map's pointer shifts direction while Cale is standing on a platform on Sessarim.

    And pardon me, Dan004, but the current description is a clunky read. Might I suggest this rewrite?

    Something that looks innocuous and featureless actually has some writing on it. You aren't able to see it with the naked eye: you'll need some way to reveal it.

    A simple example is writing a messsage with citrus juice. Once it dries, the print becomes invisible. One must warm the paper to reveal the words. Other times, you will need specialized equipment such as a fluoroscope or a chromatic filter to view the writing. In fantasy worlds, magic or Green Rocks are needed to make the writing visible. Possibly, the writing can only be read by a specific person, or at a specific time frame or location. Otherwise, the writing is invisible.

    As with any secret message, this is done so the message can't be read by just anyone, and can easily be overlooked during a search.

    May lead to Fridge Logic: if one uses an "invisible ink" to write, wouldn't the writer have a hard time writing it? (It may be handwaved by turning the text invisible after it was written, in some way.)

    Truth in Television: this was a valid secret communication technique right until the 20th century, when UV lamps (a/k/a "Wood's Light", "black light") rendered it obsolete.
  • December 18, 2015
    zarpaulus
    ^ UV ink and lemon juice are completely different things.

    UV lights used to be uncommon, but now they're so popular that they're used in kid's toys.
  • December 18, 2015
    AgProv
    {{AC:Real Life]]
    • A really Squicky example: fresh male sperm may be used as an invisible ink much as lemon juice may be applied. apparently all men can access a stock even if in a place where no lemons are available.
  • December 18, 2015
    DAN004
    ^ Perhaps I'd like to see a case where that is really used.
  • December 18, 2015
    sgamer82
    • Parodied in the Discworld book Witches Abroad. The witches come upon a dwarf mine, identified by invisible runes. Magrat states she can't see them, which Nanny Ogg points out is how you know you got your money's worth with invisible runes.
  • December 19, 2015
    oneuglybunny
    Advertising
    • A few breakfast cereals during The Seventies would print trite messages on the boxes, disguised as random dopplings of color. A piece of tinted cellulose, usually red, was used to screen out the "noise" colors, leaving the remainder to form legible print.
  • December 19, 2015
    KZN02
    See also See The Invisible on ways to make things visible.
  • December 21, 2015
    gallium
    launch launch launch
  • December 21, 2015
    DAN004
    ^ Maybe later at night, too busy for now.
  • December 25, 2015
    DAN004
    Mr. morenohijazo, can you explain what you have edited?
  • December 25, 2015
    morenohijazo
    I just added some examples that were missing, such as that one from Witches Abroad. I think it fits.
  • December 25, 2015
    eroock
    One could search the main page for "invisible ink" to find more examples.
  • December 25, 2015
    Dalillama
    Also in Discworld
    • The Unseen University faculty includes the Reader in Invisible Writings.
  • December 25, 2015
    jormis29
    • Elementary: When Sherlock and Joan retrieve the Body Of The Week of the "Art in the Blood" episode for an autopsy, they are more than a little surprised to find that his apparently ordinary arms had been stolen and nothing else. After some investigation they find out that his ex-wife is a tattoo artist and he had her cover his arms with tattoos that only show up under UV light.
    • Blindspot: Jane Doe's body is already covered in tattoos that contain hidden meanings but in the "Bone May Rot" episode, it is discovered that she also has tattoos that are only appear under the exact frequency of UV light that used for decontamination at the CDC.

  • December 26, 2015
    morenohijazo
    ^^^ There's no main page for invisible ink. Am I missing something?
  • December 26, 2015
    Folamh3
    May I suggest folderizing this trope before launch?
  • December 26, 2015
    DAN004
    ^ Well, done.

    And well, I can say... Final bump.

    I might launch this tomorrow, or maybe someone else will? :D
  • December 26, 2015
    randomsurfer
    ^^^I believe the suggestion is to do a site search for "invisible ink" (including the quotes) in order to find any & all examples already on the wiki.
  • December 26, 2015
    eroock
    ^ Correct. Main site search as opposed to YKTTW search.
  • December 26, 2015
    jormis29
    Something to add to the Arrow example:

    The team finds some notes written the same way in Sara's boot in "The Magician" episode. Nyssa calls it "Ghost Ink" and says it is one of the standard methods that the League of Assassins employ for concealing secrets.

  • December 26, 2015
    oneuglybunny
    Film
    • One Charlie Chan mystery Charlie Chan in Shanghai has some writing on a piece of linen. The glyphs appear to be Chinese, but Chan declares them as gibberish. He then points out that, despite plenty of writing paper available, the marks were made on cloth. Chan rinses the linen in a bowl of water, which washes away some of the ink, but leaves the true message in broken Roman letters intact.
  • December 27, 2015
    eroock
    ^ Google says this happened in Charlie Chan in Shanghai (1935).
  • December 27, 2015
    oneuglybunny
    ^ Thank you so much, eroock, that's the one. :) Amending that example forthwith.

Three days must pass before this YKTTW is Launchworthy or Discardable