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Molly Cule
169274.  Tue Apr 24, 2007 6:02 am Reply with quote

Why do the US post-office use invisible ink?

To help them sort the post more quickly. The US Post Service uses invisible ink to print bar codes on mailed envelopes giving routing information for use by mail handling equipment further down the line before delivery.
s is admittedly wikipedia, Justin knows of 'invisible' purple dots on his letters.

Molly Cule
169275.  Tue Apr 24, 2007 6:02 am Reply with quote

You can buy invisible ink to use in your inkjet printer.

This is used a lot for printing information on business forms for the processor of the forms without cluttering the form itself with visible information.

169290.  Tue Apr 24, 2007 6:48 am Reply with quote

Molly Cule wrote:
You can buy invisible ink to use in your inkjet printer.

What a magnificent fact! It'd be nice to get such a cartridge, and print something invisible in the studio. Perhaps even ... an invisible elephant!

169308.  Tue Apr 24, 2007 7:31 am Reply with quote

Excellent idea.

Bit hard to run a printing test to see if you've run out of ink, though.

169311.  Tue Apr 24, 2007 7:37 am Reply with quote

Well, that's how you’d start, isn't it? Stephen prints something off to test whether there’s enough ink. Looks at piece of paper - nothing on it. “Ah yes, that all appears to be working fine ... ”

169312.  Tue Apr 24, 2007 7:39 am Reply with quote

Great stuff, Molly.

As Mat suggests, only cheaper: we could simply hold up a blank sheet of paper and boldly assert that there is an elephant printed on it.

169321.  Tue Apr 24, 2007 7:51 am Reply with quote

Untruths? Gasp! There might be children watching!

169826.  Thu Apr 26, 2007 6:11 am Reply with quote

A nice corollary to the invisible ink, is that legal documents such as wedding certificates are signed in special thicker ink which is designed to grow darker with age.

The ink contains a cocktail of chemicals that react with the surface of the paper and oxidise, turining to a black that will not fade in sunlight and is resistant to water.

S: Colour, Victoria Finlay

169828.  Thu Apr 26, 2007 6:16 am Reply with quote

Why do all marriages begin with a certain amount of vitriol?

Becasue the above ink is made from normal dyes, tannic acid, gallic acid and iron sulphate - a chemical better known as green vitriol.

s: ibid

169855.  Thu Apr 26, 2007 8:19 am Reply with quote

In rubbish detective films, the conspicuous spy might be seen moving his eyes from left to right. Well it turns out that such eye movement improves your memory.

Horizontal eye movements are thought to cause the two hemispheres of the brain to interact more with one another, and communication between brain hemispheres is important for retrieving certain types of memories.

Christman said he has received many letters from people wondering whether horizontal eye movements could help them in their everyday lives.

“Let’s say you’re leaving a mall after a long day shopping and you realize, ‘Oh God, I can’t remember where I parked my car,’” he said. “Would it help you if you stood there in the parking lot and just wiggled your eyes back and forth for 30 seconds?”

He’s not sure, he said—but it might be worth a shot.


169950.  Thu Apr 26, 2007 12:40 pm Reply with quote

Re: invisible ink.
Lenin used invisible ink (milk) when in prison and when in exile near the Razliv Lake ("Razliv" - ironically - means "spillage" in Russian). When the milk dries, one cannot see what was written, unless it was a very fatty milk! When you hold the piece of paper above a candle, the letters come through (in brownish colour).

180135.  Mon Jun 04, 2007 6:08 am Reply with quote

Prominant mathematician Marius Sophus Lie was arrested in 1870 in Germany in suspicion of carrying coded messages.

Of course the so-called codes were algebraic notes.


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