im sure everyone has seen sticks on dynamite in movies and history documentaries. they even used it in myth-busters a few times i think, but how much force would it really take to set it off?
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Nitroglycerin is an oily, colourless liquid, but also a high explosive that is so unstable that the slightest jolt, impact or friction can cause it to spontaneously detonate. Since the molecule contains oxygen, nitrogen and carbon, when it explodes a lot of energy is released as the atoms rearrange to form new molecules with strong, stable bonds, like N2 and CO.
Dynamite is (by design) *way* more stable than nitroglycerin, even though nitroglycerin is the underlying explosive it uses. It’s stable enough to still see some use, although it certainly requires some caution.
Nitroglycerin, on the other hand, is *very very very* unstable stuff. Nitroglycerin can be set off by gently tapping it – in more technical language, it’s a contact explosive. [This video isn’t of nitroglycerin, but it should give you something of an idea of what we’re talking about here.](https://en.wikipedia.org/wiki/File:Detonating_Nitrogen_triiodide.webm) (the explosion in this video is 15 grams of material, roughly a grape-sized chunk). Notice how in the very slo-mo version played late in the video, the explosion has covered a big chunk of the room *before the sound of it can even reach the camera* – in other words, the blast is far faster than the speed of sound.
Dynamite and nitroglycerin are different but related explosives. Nitroglycerin is not hard to set off and things such as dropping it on the floor might be enough. However dynamite is made to be quite stable. It can be dropped into mining shafts and even set on fire without exploding. That makes it quite easy to transport. In order to set off dynamite you need an explosive shockwave already formed. This is accomplished by detonators that is pushed into the end or by bundling several sticks together and detonating one.
Yay, explosives. I love explosives. They are fun. I’ve actually made nitroglycerin. It was a controlled training environment for work, not a backyard experiment. Do not try yourself.
There are a lot of factors that effect explosive sensitivity. Generally, the sensitivities fall into 3 categories: heat, shock, and friction. Nitroglycerin is pretty sensitive to all three. But as stated before, how sensitive is related to several variables. How well it was made is one. Impurities or leftover acid from manufacture can increase the sensitivity greatly. Next is what condition its in due to age/storage. Nitroglycerin is normally a liquid, but it can crystalize over time. These crystals are extremely sensitive to shock and friction. So if you pick up a stick of dynamite that has begun forming crystals, you are gonna have a bad time. Breaking a crystal (shock) or dragging them across each other (friction) will very easily start a detonation.
Fresh, well-made nitro is less sensitive than what I’ve talked about before, but its still very sensitive. You can handle/move it carefully without worrying about it detonating. It does fail the hammer test though. Yes, the hammer test is a real thing. You place a small amount of the explosive being tested on a piece of metal (or a hammer) and tap it with a hammer. A bang means its pretty sensitive. Nitroglycerin goes bang, every time.
In high school I would make Nitro.
We would detonate it by layering water and oil on top if it (in a glass container. Then we would set a sliver of metallic sodium on top.
the sodium would sink in the oil, and meet the water with violent results.
The detonation time could be set by the depth of the oil sitting on top of the water.
We had occasional unwanted detonations from shock. it was always surprising how little of a shock it took to detonate, but then surprising how dropping a container (5 ml) did not cause it to go off. I think this is why it is called “unstable”, you don’t really know what will cause it (minimum force accidental) to detonate.
We also played with [picric Acid](https://en.wikipedia.org/wiki/Picric_acid) which was in a solution or under a liquid. Some times the crystals would grow dangerously large. I’m told that it can detonate under gravity pressure within the crystal structure. We never had any unwanted detonations with this or [ANFO](https://en.wikipedia.org/wiki/Ammonium_Nitrate_Fuel_Oil).
Nitroglycerin is a demon high explosive. Know how unstable it is in old cartoons? The real stuff is **worse**.
In the 19th century it was the only high explosive available. High explosives were extremely useful in mining to shatter rock. Gunpowder is a low explosive. The difference being akin to patting someone on the cheek and a hard slap.
So nitro is so dangerous and killed so many people it gets banned. Dynamite gets invented and it’s a godsend. Nitroglycerin but actually safe to use. Mostly harmless anyway. It does have a tendency to sweat pure nitro…
Thing is… The active ingredient in dynamite is still nitro and nitro is illegal therefore dynamite is illegal…
So in a western story if people are acting weird about dynamite this is why.
Modern day mining uses anfo which is a mixture of ammonium nitrate (fertilizer) and fuel oil (diesel). Its dirt cheap and well behaved.
Dynamite original was saw dust soaked in nitroglycerin and although much more stable than pure NG was still moderately sensitive to shock. Modern dynamite is usually much more stable and can resist alot of shock. I wouldn’t go shooting it or smacking it with a hammer but there’s a pretty good chance you’d still be safe
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