Sometimes, quirky products get created. Like a spray to see the contents of an envelope without physically damaging it. I can only imagine detectives and those who need to operate below the radar being very excited about this. Now if only one could come up with a letter that is an envelope, that would be more interesting, taking into account the tons of paper wasted, and the sheer number of envelopes we throw away.
It is aptly named X-Ray Envelope Spray, and is rather self-explanatory. It is a bit like spraying an envelope with water, but not getting it wet.
If you are really keen on this kind of PI stuff, you can get a can at $15 USD here.