How to Make Black Powder or Gunpowder
Gunpowder or black powder is a mixture of sulfur, charcoal, and potassium nitrate (saltpeter) that has been used since the 12th century for fireworks and later as a propellent and explosive in weapons. It isn’t particularly efficient or safe for use in weapons, plus it produces a lot of smoke, so black powder has largely been replaced for those purposes by other compositions (e.g., pyrodex, shown in the photo), but black powder still has its place in pyrotechnics and as a propellent for certain firearms. You should know how it is made for historical reasons if nothing else. As with my ammonium sulfide stink bomb, if you decide to try these instructions yourself, use proper safety precautions. Be advised that the main problem with black powder is its tendency to ignite from static electricity. Keep this in mind and only use wooden or clay tools (e.g., wooden salad bowl). Store gunpowder in paper or cloth, never plastic (which may build up static).
Black Powder or Gunpowder Ingredients
The usual mixture consists of 75 parts potassium nitrate, 15 parts charcoal, and 10 parts sulfur.
- 75 g potassium nitrate (KNO3, saltpeter)
- 15 g charcoal (ideally from burning the wood of a willow or linden, but other sources work)
- 10 g sulfur
- distilled water
Making the Black Powder
There are different ways to do this. One is to mix the dry ingredients in a ball mill (like a rock tumbler) with lead balls (not steel! they can spark), run the ball mill about 2 hours, then filter the resulting black powder through a strainer so that the lead balls are retained in the strainer and the black powder is collected onto newspaper or cloth. The black powder is wrapped up and stored in a cool, dry place until use.
Since not everyone has a ball mill, the most common way to make black powder yourself is to do this:
- Grind each ingredient separately until it is a very fine powder. I recommend using a mortar and pestle for this, which you can get at any cooking store. If you are grinding each ingredient using the same bowl, rinse it out when you switch chemicals. (Traditionally you would add a little water or wine to dampen the ingredients and grind them all together at once, but that’s unnecessarily risky, in my opinion.)
- Boil your water.
- Put the potassium nitrate into the bowl. Add just enough boiling water to thoroughly wet it.
- Add the sulfur and charcoal.
- Stir the mixture for several minutes. It should be uniformly black.
- Allow the mixture to air dry. This is usually done outdoors on a warm, sunny day. Some people prefer to spread the mixture out onto newpaper to dry. Others mix in a bit of alcohol to speed the evaporation of the water. You don’t want to over-dry the black powder, since that will lower its effectiveness.
- When your black powder is dry, wrap it in paper or cloth and store it until use. This should be obvious, but don’t store it near heat or flame. If you make multiple batches of black powder, it’s not a great move to store it all packed together.
Black powder is used to produce a loud ‘bang’ in fireworks and as a propellent. Yes, it can explode, but so can a can of cola in your freezer. I’m not saying making it is risk-free or smart, just that black powder is mainly used for entertainment purposes, not destructive purposes. Now that you know how to make black powder, my next post will explain how to make a basic firework using it.