ABOUT POTASSIUM NITRATE
By weight makes up 75% of the black powder you are making. I’m using tree stump remover. There are other sources, but I’m not up to digging in bat caves, chicken coops or out houses. Many instructions tell of pulverizing Potassium nitrate in a ball mill, but it devolves in water. What ever pot you use put the PoNi alone in the pot with enough water to cover it. Bring it all to a boil stir until the PoNi dissolves. You may need some more water.
I use an old aluminum nonstick frypan stir with a wooden spoon.