In article , Dan
wrote:

An unexpectedly fast burning fuse can toast one's fingers while
testing. If you want to see a test of relative burn rates between
smokeless and black powders burn a spoonful of each. Use a blowtorch to
ignite the black powder. It will burn fast enough to extinguish the torch.

And the amount of black powder that you light up can affect what it does.

A bigger pile can blow up in your face instead of just a little puff.