How to make it: first you'll need a good scale, accurate to at least .1 grams, then, weigh out the three materials you need like the chart below, the parts are my weight which is why a scale is important to good black powder.
Potassium nitrate: 75
Charcoal is important, if it's not high quality your powder wont be as fast but will still be serviceable, the best wood seems to be willow, some people have said alder works good too, I personally have had good luck with pine. Once you have a high quality charcoal and you've mixed up all the ingredients, you need to put it in a ball mill to grind it up.
Ball Mill: This is necessary for black powder, you can but small ones for $50, however these are very bad and don't tend to run at the requierd speed and will break at some point, the best thing to do in invest in a good mill from the beginning, this will save you money in the long run, or you can try and save money by making your own ball mill, as many people have done – Normally, it ends up not saving you much money if you don't have all the stuff on hand. The larger the diameter of your drum the faster you can make high quality powder, as far as speed goes, for a smaller barrel of about 3-4" in diameter 90-105 rpm works effetely, a larger drum like 5-6" will do well at 70-85 rpm.
You can also mill each item separately and then screen all the stuff together about three times. if you just choose to mill everything together, you should add 5% dextirn in the last half hour of milling.
It should be a very fine powder, much finer than powdered sugar, now the next step depends on what you want to use it for, for lifting shells, general use, star guns, and mini shell breaks, you want to granulate it, granulating is basically turning it into very small chunks, I know this seems pointless because you just spent 6 hours waiting to get it in to this nice powder, but what granulating it does is when its packed together it leaves little gaps in between each little "granule" which lets the flame pass though lighting all the powder at once, if it's not granulated and packed together the flame can't get through and only burns form one end to the other, and makes it slower.
Granulating: get your very fine black powder ready in a bowl, then mix together 25% isopropyl alcohol and 75% water and add it to a spary bottle, spray your black powder with your water/alcohol mix until it will clump together, if it clayish than its too wet, it shouldn't look shiny, if it is, it's also too wet. For the last step in granulating your black powder you'll need a screen or a tea strainer, have a few pieces of newspaper below your tea strainer and push your black powder ball though the strainer/screen, it should drop out on the wax paper about the size of table salt, then just wait 14-28 hours (depending on your granulating size) for it to dry and your done.
If you plan on using your black powder to break shells larger 3" and up, you need to make black powder coated rice hulls; basically, you wet your black powder with the same mix you use for granulating it but add more, so your black powder forms a slurry and wash you rice hulls in this slurry and leave in the sun to dry. You can use dried crumbled corn cob, puffed rice, and many cereals in place of rice hulls.
Tips and tricks
The longer you mill, the faster your powder, up to about 8 hours, then, it really dosnt make a diffrence.
the better your charcoal the faster your BP.
Granulate with dextrin.
Make sure your scale is accurate to at least .1 grams
If your charcoal is not easy to crush, it's not done.
When milling fill your jar with about 50% media, and then about 25% black powder
If you have more tips that you use, please comment, I'd love to add them to the post
And I'll try and get pictures coming soon.
Thanks to Dagabu for helping correct some of my mistakes, and more corrections are helpful and accepted.
Edited by Updup, 15 October 2009 - 06:35 PM.