I carry a powder on every flight in my carry on. I have never anywhere had a question. I have worried about it, but never a question. Kindles, smartphones, electric toothbrushes all have had queries; powders never, ever.

The only time there was an exception was at LIS when looking through my bag because of my Kindle the agent asked if my powder worked well, because it was labeled in Portuguese and she could understand what it was for. I responded in the affirmative and she said she'd go looking for it in Lisbon. That's it.