^
Starting from urine or bird guana, pretty hard (and stinky), what with the boiling-down and crystallization process to purify the nitrates ("niter"). Starting from store-boughten saltpeter (potassium or sodium nitrate, potassium preferred), sulphur and charcoal, not too bad.
But remember that the old powder mills were built with very stout framing, with the siding and roofing just tacked on so when something went flooie, they could clear out the bodies, tack the roofing and walls back on and get going again. So be careful! (They used bronze and brass tools around the mills to prevent sparks.)
Here's a great book on it... very detailed:
Hatcher's Notebook (which is now on-line somewhere) has some starting information on it so you can get to know what it's about in a rudimentary way on page 300 and following.)
Other sources for details abound:
http://www.dogpile.com/info.dogpl.t...topnav&fpid=27&q=how+to+make+black+powder&ql=
Do not confuse Black Powder with Flash Powder.
The other kids and I in our neighborhood in the late forties and fifties were "into" it and we almost had formal contests as to who could make the best stuff, but this was before any of us knew about the incorporation process (grinding the ingredients with a small amount of water), so ours just sort of went fzz! real fast, but not with the fwump! of commercial black powder. We still made our cannons go bang, however.
We got our saltpeter from the local butcher shop... no legal problems whatsoever back then. Sulphur was from "Flowers of Sulphur" from the drugstore, and charcoal was obtained from cooking charcoal or Requa's charcoal tablets for flatulence. (Do not use charcoal briquets, which had not even been invented back then, and are impregnated with oils for lighting and as a binder.)
In about the '60s I learned about the incorporation process and made small amounts of it just to try it out. This stuff made the fwump! with a satisfying mushroom cloud, but it was nowhere as good as commercial powder, so I was satisfied with the process, had "proved up" on the idea, and abandoned making any more.
I lived in the city in an apartment at that time, and the great gouts of smoke generated by these experimental batches which I tested indoors were getting a little <ahem> obvious, even though I was only setting off half a teaspoon or so at a time.
Terry, 230RN