Doesn't appear to defeat security envelopes either, which have been around for quite some time.

-----Original Message----- From: David Honig [mailto:honig@sprynet.com] Sent: Thursday, December 14, 2000 2:06 PM To: R. A. Hettinga; cypherpunks@algebra.com; cryptography@c2.net Subject: Re: Perry's Paint Fable comes to mind...

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FOR ALL TO SEE It's a spray which renders sealed envelopes transparent, making the letters inside as easy to read as postcards. "It leaves an odour for 10 to 15 minutes," says the spray's inventor, but, apart from

At 03:50 AM 12/14/00 -0800, R. A. Hettinga wrote: that, "no

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evidence at all" that it's been used. While the manufacturer describes "See-Through" as a "non-conductive, non-toxic, environmentally safe liquid", human rights activists believe "it's an ethically questionable product" which could tempt security forces to bend laws. http://www.newscientist.com/news/news.jsp?id=ns226930

[Lighter fluid and similar stuff works just fine. That's been known for over a hundred years... --Perry]

Wouldn't this be detectable if you scrawled on the envelope with an ink succeptible to paper chromatography in that solvent?

You can make primitive (before cheap float glass) windows by oiling paper...