On Sat, 17 Nov 2001, David Honig wrote:
At 10:57 AM 11/17/01 -0800, Sandy Sandfort wrote:
Airport chemical "sniffers" apparently look for the signature of nitrogen compounds, not "explosives," per se. I've often wondered how many weekend
Unless they look for nitrogen in bulk of the specimen (PGNAA), a very expensive/low-processivity technique unsuitable for mass luggage screening they're limited to stuff stuck to surfaces (lasers, swabbing/ion motility spectrometer) and volatile sniffers (chemical sensors, canines). Many classes of explosives contain no nitrogen, many of those which contain nitrogen and are free of volatile tracers don't emit much volatiles, if properly packaged even very volatile explosives (say, methyl or ethylnitrate) can be sealed (glass bottles). Generally, the maker and the packager, unless they work very cleanly/are suited should not be the courier, nor the outer containers be present in the contaminated area. In short, detection probability is only high for sloppy/dumb people.
gardeners have gotten hassled and delayed because of trace amounts of ammonia-based fertilizers on their person and effects. If you plan to fly,
Salts are different from traces of uncombusted nitrocellulose deposited on any surface of a nearby gun being fired.
be sure to wash your hands thoroughly before heading out for the airport if you have been shoot, gardening or house cleaning.
I've wondered about that too; airport sniffers must have encountered Miracle Gro and angina nitro during the early days, measuring
Nitroglycerin is not volatile, is present in large dilution (~0.1%) in small quanitities (pharma bottle). Ditto nitrate salts in a water solution.
a false alarm rate. Shooting is scary; you could contaminate your car driving back from the range, then contaminate your travel gear.
I think you should be able to get a good positive if you'd fire several rounds of vanilla smokeless with baggage surface being near the muzzle of the gun. Try it sometime, if you're unafraid of winding up in a database. I've found that transporting computer parts (motherboard) in hand luggage can suffice to trigger swabbing (if you're really bored you can discuss detection of Semtex traces with airport security).
The explosives expert in one of the older terror trial docs on cryptome says things suggesting that a few washes will remove traces. (And contaminate clothes washed with them.)
Just use an overall when you're at the range, and wash it separate.
I once checked out the screen on a sniffer, and they list "nitrates" as a category. I suppose having PETN (another category) detected on your laptop would be harder to explain :-)
If you want to fool the security, you should become familiar with the type of detectors used on your luggage. Of course, best solution is using human factors to not have your stuff being screened at all. -- Eugen* Leitl <a href="http://www.lrz.de/~ui22204/">leitl</a> ______________________________________________________________ ICBMTO: N48 04'14.8'' E11 36'41.2'' http://www.lrz.de/~ui22204 57F9CFD3: ED90 0433 EB74 E4A9 537F CFF5 86E7 629B 57F9 CFD3