Secret Ink

Secret Ink

 

a chemical compound in the form of a colorless or faintly colored liquid used to write secret messages. The juices of certain plants are sometimes used as secret inks. A text written with secret ink is invisible under normal conditions. In order to make the text visible, the document must be heated, exposed to ultraviolet radiation, or treated with chemical reagents.

References in periodicals archive ?
It produced 857 litres of secret ink added to the coloured material to seal meat at all the butchers in the country.
While Al Qaeda mainly hid in the shadows of the Internet using it as a modern drop box or secret ink, Militants noisily using it to advertise itself, radicalise new recruits and intimidate with grotesque videos of beheadings, he said.
London, July 13 (ANI): A series of declassified documents that show how the French cracked Germany's secret ink formulas dating back to World War One has been put on display in Washington D.
Postal Service Inspectors how to detect letters written in invisible, or secret ink.
Another memorandum dated June 14, 1918 - written in French - reveals the formula used for German secret ink, it added.
He couldn't build a radio mix secret ink or recruit a network.
Elsewhere, the DD collection includes jig saw puzzles, board games, spacemen sets and even a painting by numbers set and another favourite comprising a tie clip, a tin of tooth powder, another containing secret ink and a pair of field glasses, all licensed by Eagle Comics and all dating from the 19650s and 60s.
There's a colourful array of Dan memorabilia in the Christie's sale, including stencil sets, jigsaw puzzles, ray guns, walkie-talkies, pocket-watches, games, a radio station, lead figures, and even secret ink and toothpowder.
Police have been marking bottles of booze with secret ink in an effort to catch out under-age boozers.
Agents were armed with suitcase bombs, explosive clogs, secret ink and even incendiary cigarettes which created "a hot flame for five seconds" when lit.
He couldn't build a radio, mix secret ink, or recruit a network.