First and foremost: do not do this. Black powder is incredibly dangerous and it is very likely that in the process of attempting to make some, you will:
- Be arrested, charged, and imprisoned
- Be maimed
- Get poisoned
- Burn your house down
If you agree to never attempt to manufacture any, you may read on.
After having found a reliable and inexpensive source of potassium nitrate for making rocket motors, we thought we'd branch out and use the oxidizer for something different: black powder. Black powder is incredibly simple, and can be made with three basic components:
You need a handful of other things to actually manufacture it, but with one exception (alcohol or acetone) it's all equipment.
First, you need to get the three core components listed above. The potassium nitrate can be purchased at many home improvement stores, or online. Try and get a non-pellet form of it, though, the pellets tend to be made with a binding agent that burns horribly. Find a KNO3 source that is already granulated or pulverized in some way. Anything but pellets. We got our sulfur on amazon, and our carbon source was ground up hardwood charcoal. DO NOT use charcoal briquettes. They, too, are made with a binding agent that burns horribly.
Combine the components in a 75:15:10 (KCS) ratio. For example, to get 200g, prepare 150g KNO3, 30g carbon, and 20g sulfur. We found the fastest way to mix them was to dump them into a blender and grind them into a pureé of death.
Once combined, dump the powder into a plastic container of some sort. Pour in a small amount of denatured alcohol so you have a thick msuh. Mix the slurry generously so as to make sure there are no lumps of KNO3 or sulfur. These tend to cause a lot of problems.
Get a very fine mesh strainer, and, using the back of a soup spoon (or similar), mash the gunpowder-mush through the strainer in such a way that the grains fall onto an appropriate drying surface. We used tin foil exclusively. The powder will then take some time to dry, though leaving it in the hot sun on a calm day will cause it to dry fairly quickly. You can also mount a high wattage lamp above it, and while it will dry the powder much faster… it is considerably more dangerous.
When the powder is fully dried (no scent of alcohol should be even slightly detectable) pour it into a safe plastic or glass container.
Impossible? Feh! You heard wrong.
A lot of sites say it's very hard to manufacture black powder that's any good, but we found them to be dead wrong. We manufactured black powder with no issues and experienced very few if any problems with our product. So, if anyone tells you black powder is not worth manufacturing you should probably listen to them and not make any because you're going to end up killing yourself.
Do whatever you want. You may want to get some fuse, though, because lighting it directly is pretty stupid. We suggest keeping a small jar on your shelf with a label that reads “Black Powder” because, lets face it, that's pretty cool.
And if your house is going to burn down, a few hundred grams of black powder in a jar probably isn't going to do that much more damage.