Transperancy Spray?

Karsten M. Self kmself at ix.netcom.com
Tue Oct 30 14:40:09 PST 2001


on Tue, Oct 30, 2001 at 10:25:54AM -0800, mmotyka at lsil.com (mmotyka at lsil.com)
wrote:
> >> Well, I was watching CNN and it looks like the Postal workers now are
> >> armed with a new weapon.. Against terror of course.  THe whole cant read
> >> someone elses mail thing is out the window it looks like, they can spray
> >> this go on the letter and read through the envelope..  It seems
> >> implausable but its CNN, they dont lie right? well ANYWAYS, I now have a
> >> nice stash of black construction paper...

> Yes, that would work nicely as the outside sheet.

Or "security" envelopes, possibly.

> >    "You spray it on and it temporarily makes the envelope clear," said
> >    Robert Schlegel, vice-president of the makers, Mistral Security, of
> >    Maryland. "It leaves an odor for 10 to 15 minutes, but there is no
> >    smudging of ink, no stain, no evidence at all. The envelope is
> >    transparent for a few minutes and you can respray it hundreds of
> >    times without leaving any stain."

> I would bet that there is SOMETHING that is dissolved by liquid freon.
> Just mark your letters with the stuff and look for the integrity of the
> mark at the other end.

First, is that what this spray is?  Any information on the chemical
composition?

Freon's pretty chemically inert.  That's among its advantages, though
it's a liability in the upper atmosphere.  Other options might be some
indicator that notes a rapid change in temperature (evaporating
refrigerant does a nice job of lowering temperature quickly), or
presence of a fluid.  Even a nonreactive chemical could float something
loosely applied to a letter.

Peace.

--
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