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The History of Invisible Ink
As a kid I had a minor obsession with invisible ink after learning about it in a science club. An impressive stack of vinegar and lemon scented papers filled my desk, but the history of invisible ink is much more interesting than a summer enrichment program. Starting with the Roman general Pliny the Elder using milk from the thithymallus plant, to modern inks which are only visible under UV light, the science of invisible ink has grown quite complex. Some of the oldest CIA documents contain recipes for special inks, and MI6 and their very own "adult" mixture during WW1.
That's really his name?
Couldn't have asked for a better name...
... was "making enquiries for invisible inks at the London University".
From the last link:
Mansfield Cumming,
In October he noted that he "heard from C that the best invisible ink is semen", which did not react to the main methods of detection. Furthermore it had the advantage of being readily available
Dried semen shows under two well known "development" methods, both heat and UV. Better to use "ink" that only show under uncommon reagent, but that user would be reasonably expected to possess for another use.
An old Roman version of invisible ink can be made in your own home. You need to collect your urine for several days and keep it uncovered in the sun so that it becomes more concentrated. keep it inside, like on your kitchen counter so it doesn't become contaminated with windblow stuff. after several days, it will become a dark amber color... this is what you want... for each gallon of urine, add two teaspoons of vinegar, one teaspoon of green food coloring (we're using a oxidized copper ion here), and finally, a half-cup of corn starch... mix it all together with your hands and dip a straw into it and suck it up into the straw....then start writing with it.
when it dries you won't be able to see it.
my subsequent post will tell you how to "develop" it so your friends CAN see it.
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"Lost time is not found again."
Did every MI6 agent get a stack of porn to use when writing hidden messages?
The Tao of math: The numbers you can count are not the real numbers.
Sorry, you're eight years too late:
http://99-bottles-of-beer.net/language-whitespace-154.html
Doubly invisible if you keep it in a dirty magazine. That is, it would be, if the pages wouldn't keep getting stuck together.
Or would that just make it triply invisible.
See: http://en.wikipedia.org/wiki/Whitespace_(programming_language)
- David A. Wheeler (see my Secure Programming HOWTO)
Bet you cant
read that!
Noodlers Blue Ghost is a really sweet ink to use for just that. Very invisible and very UV. Gewgle it.
Then theres a fountain pen ink called Noodlers Blue Ghost, which is very invisible, and highly flourescent under UV light. Awesome stuff I have a 3oz bottle. Of course this is eel based, I'm sure. Gewgle it eh?