This product is used to reload pistol (magnum) and shotgun shells. Smokeless powder contains nitrocellulose or nitroglycerine or both and is exactly the type of explosive that Sniffex is advertised to detect in small quantity.
I weighed out three one ounce portions with a postal scale and placed them into small plastic bags which in turn, I placed into bubblewrap-padded opaque manila envelopes.
I then did the same for 18 envelopes which contained plain table salt. To avoid contamination, an all fresh setup and disposable plastic spoon were used to make the salt samples. I made two sets containing 9 salt envelopes and 1 gun powder envelope each. All envelopes were labelled only with a letter or number and sealed. After I was finished I did not recall which envelope held the gunpowder. For the experiments, I placed the envelopes where requested by the testers. I handled and placed them upside down so that nobody, including me, could see the labels.
I made two additional "known" samples -- one salt and one gunpowder, each of which was clearly labelled with the contents (below is the gun powder sample). These were used to show that the Sniffex devices were working in their customary manner so that nobody could later claim they were defective.