My question, Why is it burning so slowly or is his recipe wrong??
I would like to drop a book on that slow burning pile to see if things speed up a bit.
I'm no eggsurt but, he skipped a couple steps. The mix he got should then be combined with a solvent,(IIRC water), then made/cast into a "cake". That thoroughly mixes the ingredients, then the cake is broken up to produce the 5 grades sporting black powder is made in. 4f, 3f, 2f, 1f, and cannon grades.
That's how I understand it anyway, I'm certainly NOT going to try it myself.