'Spy Spray' Reveals Secrets of Mail
by Keith Perry
The Guardian, 2000-12-14, page 13

The secrets contained in our private mail may not be secret much longer, thanks to an invention by a team of American scientists.

Researchers have developed a spray that makes envelopes transparent and the letters inside as easy to read as postcards.  The spray leaves no trace that the correspondence has been tampered with, apart from a slight odour lasting 15 minutes.

Called See-Through, the spray is intended for use by police forces investigating suspect packages, according to a report in New Scientist magazine.

But private detectives or snoopers keen to pry on their neighbours' private correspondence are likely to be disappointed: the company which developed the environmentally safe spray, Mistral Security, based in Maryland, has said it will only sell to law enforcement agencies.

A spokesman, Bob Schlagel, said: "With a business card in a brown envelope you can read the card, the email address, the telephone number, everything.  It leaves an odour for about 15 minutes but apart from that there is no smudging of ink on the envelope or letter, no watermark, or any evidence at all."

John Wadham, director of Liberty, the human rights organization, said police would need a warrant to use such a spray to examine letters.

But Simon Davies, director of Privacy International, a London-based human rights group focusing on surveillance issues, said the spray could tempt security forces to bend laws.  "It's an opportunity for governments to sidestep legislation."


Enclosing a letter within a couple of layers of newsprint should make it
rather more difficult to read using the See-Through spray.

And before long perhaps we may have a spray ("See-See-Through"?)
to enable us to detect whether See-Through has been used on our letters.
(A hint for entrepreneurs looking for a need to fill.)


See also Endangered Spaces: Privacy, Law And The Home, which "brings together all the elements of the law relating a person's right to enjoy privacy in their home — from trespass to wiretapping, defending property against burglars to dealing with bailiffs."


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