I've been lurking here for most of this year, but haven't had anything to really add to the discussion.. I'm new at the game, but flying regularly, so I've been learning a lot in anticipation of being among the elite, like the rest of y'all.

However, I have seen something that I'm really curious about, and was curious if more enlightened minds had an idea.

Recently, while waiting in SFO for a United flight, I was chatting with an elderly gentleman, who mentioned a strange device at the security checkpoint. Basically, he said that they ran a white cloth pad across the handles and zippers of his carry-on, and put it into a machine. He said that the security people told him that "Each person has individually different sweat, and we're checking to make sure no one else has been handling your baggage, for security reasons." [now, I'm pretty sure that the technology exists, but I'm also pretty sure that doing this analysis takes a wee bit longer than the time you can afford to spend in the Security checkpoint]

A few weeks later, I was going through the security checkpoint, and my carry-on bag was taken from the x-ray machine rollers, and I was told that they were doing spot checks for security. The security lady ran what looked like one of those round cloth face cleanser pads across the handle and zipper of my carry-on, and fed it into a machine. I asked, and was told that it was an explosives detector. [Now, if I were lunatic enough, and I'm not, to put explosives in my carry-on, would I really rub them across the handles and zipper of my carry-on? I suspect not, but that's a side issue]

Now. Does anyone know what those things actually are, and what they're really checking? It doesn't really matter, but I'm curious as all get-out, and I don't ususally have time when I get to the airport to wander around, looking for supervisors to get an answer..

--Vird
(Almost up to 25k miles on United in the past two months!)