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I, as a hobby, do a fair amount of historical weaponry, particular a focus on firearms. As a result I have a number of black powder rifles and pistols and often times get gunpowder absolutely everywhere. This is normally fine but recently I was traveling international and got pulled aside for a swab check (see Why did airport security swab my hands with wet paper? )
Luckily they didn't detect anything but it makes me wonder, what if they had? What happens if explosive compounds are found and how can I help prevent/minmize any misunderstandings?