Originally Posted by
fireworksboy
I say this having worked in the business for the last 12 years doing everything from setting off huge display shows to backyard fireworks to working in our retail stores. My current job is to open new retail stores and I travel every week. Being in and out of our warehouses and in contact with our product on a daily basis, I've had my share of swabs and trips thru the puffer machine and I can tell you that I have never set off either - which is scary in its own right.
As was said by Spiff above, ETD and ETP look for high explosives not low explosives (gunpowder, flash powder, etc.). The reason low explosives are ignored in explosive trace testing is because they require a substantial, high-strength casing (e.g., 3/8 steel pipe, etc.) in order to be explosive (i.e., there's 0% chance they're getting through x-ray or WTMD), and any device using them will be haphazard at best.