I was trying to make gunpowder in my classroom to teach about oxidizing agents.
We had tried various combinations a few days ago with little success. Upon further research, I thought that maybe grinding the material would help.
OK,OK, I’m an experienced teacher and should not be playing with such things but you have to have fun too. This did not turn out well.
I asked a student to grind up the ingredients in a mortar. He had not gotten far before a ball of flame erupted from the dish. Luckily noone was hurt but it was a scary situation.
I thought that gunpowder required a source of ignition. Is gunpowder not ground when it is made? Was gunpowder not rammed down the barrels of cannons?
Obviously the ingredients should have been ground separately but videos I have seen show them all being ground together.
All in all, a very memorable and educational day for my students.
Gunpower is fairly granular; you don’t want dust. Grinding it too fine with too much pressure creates heat. Enough, as you found out, to ignite the stuff. While grinding, a light touch is key.
I’ve read that it’s ground and mixed wet, then dried very slowly and very carefully.
And they swabbed out cannons with a wet mop between firings. Partially to clean out fouling as you go, partially to douse any remaining sparks or hotspots so the powder doesn’t ignite ahead of time.
This is a typical Hollywood misconception. With a cannon (or a musket) you just need to push the powder all the way to the back end of the barrel (the breech). You don’t need to pound it down like there’s no tomorrow.
As Q.E.D. said, you don’t want dust. Black powder is rated by the size of the granules, Fg, FFg, FFFg, etc (the more F’s the smaller the granules). The stuff they used in cannons was very coarse. My civil war style musket uses FFg, which is a lot finer than the stuff they used in cannons.
Very tightly packed powder makes more of a flash than a boom. Very loosely packed powder makes a nice boom. Dust makes a big BOOM. Be careful.
FYI - Static electricity will also ignite gunpowder.
Hell, it doesn’t even have to be gunpowder dust!
Very true. Blow a small cloud of flour over a candle some time. Make sure you aren’t too close or you won’t have any eyebrows afterwards.
Heh, many, many years ago my brother was making in science class in high school some fireworks for a school display. They went off in his face, blowing him through a door and sending him to hospital. He wasn’t permanently damaged, but legal stuff ensued (the school settled). Years later, he was still picking bits of glass out of his flesh.
Well, a few years later I was in the class and had the same teacher (a very good one btw). On the first day of class he read my name on the list and asked me if I was related to my brother. When I said yes, he just sunk his head in his hands in dispair - I suspect the incident was very painful to him in many ways, it was lucky he kept his job (he never in fact mentioned the accident to me, and I never asked him about it).
Bottom line is I’d be reluctant, however fun, to have high school kids messing with explosives - simply too easy to have stuff go wrong. My brother was a very careful kid who in fact went on to be a scientist himself.
This reminds of a factoid I learned not to long ago.
I would read that Dumbass XYZ was building a pipe bomb in his basement or whatever with gunpowder. Maybe city hall was in big trouble, maybe he was just a tinkerer, or maybe he had a beaver dam that needed dealing with. In any case, the damn thing would blow up and he would at best be minus a few body parts and at worst be dead.
I always wondered. WTF was he doing to set it off ? Smoking like the Cancer man? Rubbing his sensuous body all over dry sheep first? What pray tell was setting these things off?
Yay pours the stuff in the pipe till full. Yay gets the cap. Yay starts screwing it on. Yays didnt notice the fine powder on the threads. Yays get that a fine a powder burning from friction. Itsa meets the rest of the stuff in the pipe. bada bing bada boom…
If you are trying to teach the kids about oxidizers, why not combine a gram of KClO3 and a gram of sugar on a spot plate and apply a match? Or you could just strike a match.
FWIW,
Rob
Seconded. Without oxidizer, the sugar won’t burn easily (if at all?). With oxidizer, you get a big impressive FOOSH with lots of smoke, but it can easily be contained by a sheet of plexiglass.
Perhaps you should ask Tripler to visit and give a proper demonstration?
Hoo-boy…that takes me back. During what we now know of as my tween years, I dabbled in the forbidden science of basement bombmaking. My ‘sensuous body’ was feeling invincible and managed to survive these horrifying anecdotes.
When smashing found .22 rounds between rocks for the powder (not gp, I know), I (predictably) set one off. Both ends shot off harmlessly somewhere but it was terrifying and I still remember the shock of the suprise and the loud noise and apparent brush with death.
I made a small pipe bomb out of recovered powder and a 3 inch length of copper tube. To seal the ends? Hammered shut, o’ course.
Finally, the epic battle of burning homemade ‘napalm’ (styrofoam and gasoline) vs idiot friend’s shoe: We spent an afternoon melting these large sheets of foam insulation into a mayo jar of gas and took it in back to the alley and lit it. It burned like crazy and there was a lot of black smoke so we began to panic. My friend, the older, smarter one, runs to the upright jar and kicks it over. The jellied gas slowly melts out where it burns more fiercely than ever. Genius dutifully steps on the burning goo and quickly realizes the reason such a substance may be weaponized. It doesn’t go out. He’s doing the horizontal circle run in the alley, trying to untie his buring shoe. He does manage to get it off but not before both the shoe and his pants are ruined. We run away before being spotted.
We did that too!! Pretty awesome especially when the KClO3 is melted. I was smart enough to use a fume hood.
Then we watched NOVA’s Kaboom which I had seen several times. This time I thought I would make a small batch as a test. The first tests were outside and the gunpowder was placed in a paper towel which was lit. Very disappointing. Barely a fizzle. A Youtube video showed the gunpowder being ground into a powder. The rest is high school history.
BTW it was a 10 gram sample.
But then – correct me if I’m wrong – after the powder is in, you do have to pretty firmly shove down the shot (and wad), right?
Just yesterday afternoon there was an explosion in the Lab at the Hill City MN high school. 2 students and a teacher were transported to a local hospital.
This is a small rural town and we may never hear details about this unless we know family of some involved. Then we may hear story’s wilder than the media:eek:
How do I know you ask? I am an EMT and we monitor everything in our County;)
When something like that happens and we don’t know details, speculation surfaces. I would never have though GP but after reading this thread, at 1st thinking “WOW I have to read this, how did the details make it to TSDMB” already, It “Could” be GP:eek:
Oh BTW
two other things to never do. Seriously.
Take an estes rocket engine. Put it in a vise. Hammer a nail down the exhaust nozzle. It doesnt matter how gentle you are either. They do much more than ignite (which would be scary and dangerous enough). Trust me on this one.
Sparklers. Why light one at a time when you can light the whole bundle at once and then pass em out to the kiddies? BADDDD idea. Almost as bad as the one above.
If it has not already been made adequately clear to you, you should not mess about with pyrotechnics and explosives without the requisite training, experience, and equipment. Even the professionals using standard procedures sometimes experience accidents, and doing what you describe above, in clear ignorance of proper handling and the basic physics and chemistry of pyrotechnic substances is a recipe for disaster.
Um, yeah. Unfortunately, the trial-and-error method of learning when it comes to explosives and pyrotechnic tends to come with a very steep corrective penalty for getting things wrong. If you’re going to mess about with explosives you first need to read Cooper’s Introduction to the Technology of Explosives, which is the standard reference text on explosives handling and safety.
Stranger
Boy Scout leaders are fond of this property of flour. Ghost stories around a campfire can be puncuated by tossing flour into the air over a fire. The fireball is impressive.:eek:
My eighth-grade science teacher told a story I have no cite for. He said a woman on the fourth floor of an apartment building found weevils in her flour bin. She walked down the hall and dumped it in the incinerator chute. She got a few steps back down the hall before the explosion took the end wall off the building.
Thanks. I won’t do it again. Promise.