[yarddog]

I know black powder is an explosive but did not know it was what was in the pressure cooker bomb.

There are a whole lot of much more powerful explosives and that one seemed to be just that.

[familyop]

The cheapest kind of black powder was used in the Marathon bombing—pyrotechnic powder from fireworks. The NRA posted an article about it soon after the bombing.

[OneWingedShark]

I know black powder is an explosive but did not know it was what was in the pressure cooker bomb.
There are a whole lot of much more powerful explosives and that one seemed to be just that.

The black-powder claims one reason I think it could very-well have been a false-flag (or "government sponsored/instigated") incident.
The timing and rush to blame gunpowder was just too quick, taken along with the weirdness on the official-level regarding what they knew and what they did... it's just too weird.

[PapaBear3625]

I know black powder is an explosive but did not know it was what was in the pressure cooker bomb. There are a whole lot of much more powerful explosives and that one seemed to be just that.

If you watch the videos that show the bomb going off, there's a lot of white smoke. That's characteristic of black powder.

I doubt the usefulness of this. If I was a Muslim cabbie driving somebody to the airport, I would sprinkle a bit of black powder on my fingers just before helping passengers get luggage out of the trunk. Just for giggles.

Create enough false positives and they'll toss the equipment.