> Even more absorption can be had if you use pyramidal foam

Hell, it would also make the pat-down a lot more interesting!

Thanks for the detailed answer.

Of course my original question was somewhat facetious, but I do think it's farcical that, nine years after 9/11, in order to fly within the "land of the free and home of the brave" one has to be subjected to these humiliating so-called security measures. Military-industrial complex indeed! It would be interesting to trace the political donations given by the companies that make these machines...