February 18, 2008
Making gunpowder

A few months ago, I made corned beef from scratch. Part of that process involved me using saltpeter (potassium nitrate) to preserve the beef. Of course, I knew that saltpeter is a key ingredient in gunpowder. As I learned from the Gorn episode of Star Trek, all you need to do is mix, carbon, sulfur, and saltpeter, and you have gunpowder.

I had some time this weekend, so it was time to make gunpowder.

Obviously, making gunpowder is inherently dangerous, so I was carefully in my preparation and protection.

Carbon is readily available as charcoal. Sulfur is easily found at the gardening store. Saltpeter is a little tougher to find. I'm not saying it's hard, but it's not something you can find at any local store. I had mine leftover from making corned beef.

The sulfur came as small pellets, meant for spreading in your garden.

After about 5 minutes of grinding, the sulfur was as powdery as I was going to get it by hand.

The charcoal briquettes were a bit tougher to crush. I had to apply some real force to get these into grinding size. This made a bit of a mess.

But in the end, I had the charcoal ground into a powder as well.

The saltpeter was already ground fine for food usage. The exact recipe for gunpowder varies from purpose to purpose. My recipe was:

  • 1 part carbon
  • 1 part sulfur
  • 4 parts saltpeter

As I researched this, it was interesting to learn that saltpeter is the oxidizer for the reaction, meaning that gunpowder does not need air to burn. That means you can fire a gun in outer space! The molecules of saltpeter contain plenty of their own oxygen atoms.

To grind the components together, I wore gloves, long sleeve shirt, face and eye protection. I sure many people have been hurt making gunpowder. I can't imagine what it took to make it hundreds of years ago.

After grinding for a bit, the gunpowder took on it's characteristic grey appearance. Things were looking good so far.

For the initial test, I built a small test pan out of aluminum foil. I had also picked up green fuse to give me plenty of time to get to a safe distance.

Here is a video that shows what happened with my various tests.

Sure enough, my gunpowder worked.

In the Mini Rocket test, I used an old mini rocket that normally used an insertable motor. I filled it with gunpowder and attached a fuse. As you saw, it went nowhere, but did burn nicely.

I really wanted the gunpowder to work as a propellant, so I made rocket out of a old prescription (Rx) bottle. I placed that on the launcher and again, it went nowhere. You can hear the satisfying whoosh of the exhaust, but it just went nowhere.

The flames burned out the bottom of the bottle.

For the last attempt, I put all the remaining gunpowder into a second Rx Rocket and hoped for the best. As you saw, it made a satisfying whoosh and lots of smoke, but went nowhere. The lauching pad was completely destroyed.

I really need a nozzle to focus the exhaust. ;)

In one aspect, the experiment was a success. I did make gunpowder from scratch. This was not hard, but it would be hard to make it in large quantities. However, my attempts to use the gunpowder to launch a rocket, as is often seen in fireworks, was a failure. The combination of lacking a proper rocket body and a proper nozzle to direct the exhaust proved to be a serious flaw. I could simply get a bunch of model rocketry gear, but what's the fun in that? It's much more fun to try to launch plastic prescription bottles.

The biggest mistake I made ws using my wife's mortar and pestle to make gunpowder. She was upset and now refuses to allow the mortar and pestle back into the kitchen. They are now sitting on my workbench in the garage. I have to buy a new mortar and pestle. In the future, I must avoid angering the wife.

Warning: I won't tell you not to try this at home. If you are not an adult, do NOT even think about trying this. If you do duplicate this, please be careful. Gunpowder is dangerous stuff and you need to be very careful to avoid getting hurt. Wear protective clothing and eyewear at all times. And don't use your wife's kitchen gear in your experiment.

Posted by michael at February 18, 2008 04:52 PM