I’ve seen this as a plot device in various movies and TV shows, and I know it has a factual basis. Old dynamite, especially if stored in a hot environment, will sweat nitroglycerin, which usually crystallizes on the surface. So will dynamite that has been frozen and subsequently thawed.
To the best of my knowledge, pure nitroglycerin is normally a liquid at room temperature. The fact that it crystallizes suggests that there’s something different about it than normal nitroglycerin – perhaps it’s still mixed with a small amount of clay particulate? But even if it’s pure nitroglycerin, it’s not unreasonable to think that its crystallized form might not have exactly the same properties as its liquid form. But I couldn’t guess whether this would actually have any appreciable affect on its stability.
So just how unstable is a “sweaty” stick of dynamite? I’ve dredged up conflicting opinions about it. Some people seem to think that it’s just as unstable as pure nitroglycerin, and that the slightest disturbance could make the whole thing go boom. Others are bit more, “eh…I wouldn’t hit it with a hammer or shake it like a glo-stick, but it’s not that unstable”.
Many, many years ago when I was in high school, I worked with an old-time dynamiter in a rock quarry, I learned that cases of the sticks had to be turned over periodically, or the nitro would seep out of the sticks and pool on the bottom of the cases. As you know, nitro is vastly more touchy, and the slighest bump might set it off. Of course, back then dynamite used sawdust to soak up the nitro. I think today there is different base, and perhaps that alleviates the problem.
Never heard of it crystallizing, but I would expect that it might be similarly touchy. Nitroglycerin is certainly nothing to fool around with!
As an aside, that old guy was batshit crazy, although very good at what he did. One basic rule was never, ever to keep the detonators anywhere near the dynamite, naturally. This crazy old coot would load a few cases of dynamite in the back of his pickup, then put a box of detonators in the bed too, and drive off over bumpy roads to the quarry. I always elected to walk along and catch up to him later.
OK, that was bad enough, but the detonators had to be crimped to the end of the dynamite stick. There is a perfectly good crimper to do this safely, but that guy would just slip it on the end of the stuck and crimp it down with his teeth. I quickly got an other job, but oddly enough, he was in his 60s and had done that all his life. Go figure.
It’s usually not a good idea to go to the movies for one’s facts, but I’ll just throw out that in the movie Sorceror (a remake of the French film The Wages of Fear) the nitroglycerine is liquid pooled at the bottom of the cases of dynamite (which, it’s been stated, haven’t been turned). It is kept in the case by the glassine wrapping. No crystallization there.
Dynamite, since it requires a detonator for normal use, is considered a secondary explosive*. If I were to rank secondary explosives on a list, I’d put dynamite second on the list of old secondary explosives [del]I’d call Tripler to handle[/del] I wouldn’t handle myself. Old peroxides would be first on the list.
I’ll see if I can dig up some actual numbers for you tomorrow (my books are in my office).
A primary explosive is a detonator (i.e. lead azide, although other azides are available that aren’t as environmentally unfriendly), a secondary is one that requires a detonator(i.e. TNT, PETN), and a tertiary is one that requires a secondary booster to initiate detonation (i.e. ANFO*). In general, tertiary have the most power and brisance per unit weight.
**ANFO can technically be initiated without a booster, but it’s got to be pressed or cast, and isn’t generally considered a reliable means of detonation.
If you want another unstable as shit substance, try nitrogen tri iodide
I think that was the stuff that back in my high school days we made up in lab and loved to use to smear small (reall small) bits of on doorknobs, etc. Much fun ensued.
PS - please don’t ask me to diagram that first sentence.
We learned about old dynamite in class on several occasions (and, in fact are in the division right now that deals with it), and actually, there are established procedures to desensitize the nitroglycerine to the point that it can be relatively safer to handle to your disposal site.
I say safer, since the old stuff is fairly unstable, and there’s never a guarantee you can completely desensitize the nitroglycerine if it’s under wrapped paper. Just gotta be gentle and all . . .
A teacher of mine in high school (no, NOT a science teacher) told us of a compound that one could paint onto the hinges of a locker, which, when dried, became extremely sensitive, such that opening the locker would blow the door off the hinges. I think that might be the same stuff, too.
There’s several ways to do this, and not exactly with just one particular compound. I’m uncomfortable with going into further detail, but I will say that yep, it can theoretically be done.
Tripler
We’re not supposed to say, “I can neither confirm nor deny. . .” anymore.
When I did my initial training, there was an old guy in the class (John). He knew way more than everyone, including the trainers. They would even refer some questions to him. (the law had changed and everyone had to get a new ticket)
So the question about old dynamite came up. And the answer was keep away and call in the experts. And one of the trainers looked at John and said “Which well could be you eh.” John laughed and agreed, and told us about a tunnel that was being reopened after decades of being closed. In the tunnel wall at regular intervals were little niches, just big enough for a guy to stand. Three of these has old explosives stored there, and all were weepy looking.
So John was called in; he decided the risk was too great to move the old explosives, so one by one, small charges were set next to each pile and fired. The first two went with no hitch, just the firing charge went and the old sticks were scattered about (which were collected and removed between shots).
By the third shot, some of the on-lookers and managers were getting a bit difficult about the process. Anyway, John got everyone chased off and fired the shot. And that pile WAS unstable and blew. The pressure wave and noise was overwhelming. The most vocal manager disappeared home without a word.
The trainers then used this as a backstop to our legal power as shotfirers. It doesn’t matter who the person is, they have to obey our directions. And with that power comes the responsibility. The law will pound a shotfirer into mush if things go wrong and someone gets hurt/killed.
Referring to KlondikeGeoff’s old dynamiter. There’s plenty of guys out there who do things the wrong way all their life and have always got away with it. The thing is those bad practices have caused injury or death to at least one person in the past. The reason for current procedures is written in the blood of those who got it wrong just once in the past. When you’re doing it wrong with explosives, you gotta be lucky every time.
And these days, at least around here, dynamite isn’t really used unless it’s particular performance is required. Sticks are gelled ANFO. Very insensitive.
Some material from TM 9-1300-214 - Military Explosives and Propellants and the Marine Corps Field Return Guide.
*Sensitivity as liquid - The Picatinny Arsenal impact test shows
nitroglycerin (NC) is more sensitive than mercury fulminate. *Mercury fulminate was in the first priming caps for black powder then smokeless powder cartridges.
Frozen nitroglycerin is much less sensitive
than liquid and the liquid increases in sensitivity as the
temperature rises. The most sensitive form, however, is
when crystals are in contact with the liquid. Many
accidents have occurred when frozen dynamite was
jarred while being thawed. You can find many sources that will say the opposite but reading closely (fine print as it were) it’s the thawing area that’s particularly hazardous. Nitroglycerin freezes at 13.2C, practically a balmy day :).
The crystals breakdown causing hot spots that lead to initiation and detonation. Two processes are:
Hot spots can be caused by the inter-crystalline
friction of the energetic material. Jarring or shock when the crystal structure is reverting to liquid at the thaw point of 13.5C.
Particles which are spalled off crystallite by an
incoming shock wave can form hot spots by impact on
the opposite wall of a void. Again, shock or impacts to the crystalline structure.
The military uses nitroglycerin mainly as an principle ingredient in double base propellants where it’s combined with nitrocellulose and triple base propellants where nitroguandine is also added. This effectively desensitizes the NC. It’s also added as a minor ingredient (sprayed or vapored on like cereal vitamins) in small arms ball propellant.
Commercial dynamite is used in Explosive Scent Kits for training sniffer dogs.
Some of the warnings: WARNING
Dynamite exuding Clear or Brownish liquid droplets are very sensitive to shock and therefore dangerous to transport, they should also be protected from high temperatures and severe drops and jolts. Avoid crushing, dropping, or rough handling.
WARNING
Notify OIC/NCOIC immediately if the dynamite shows signs of exudation or crystallization.
Dynamite exudes (brownish liquid droplets that crystallizes) Critical
Dynamite exudes a clear/brownish liquid that may crystallize or a residue that appears to be a white powder or a dust Critical
I’ve had to destroy the dynamite from two scent kits in my career due to exudation (liquid coming through the wrapper and crystallization in the end folds of the wrapper. There are a dozen 1/2 lb sticks in each kit. Two types: 40% NC and a non-explosive binder like a cellulose material. There is some oil added to this mixture for friction reduction. The other type mixes NC with ammonium nitrate. We couldn’t transport at this point - forbidden in the rule books. A back loader came out from the main base to the ammunition storage area; dug a hole ~6 ft deep midway between the explosive storage magazines. I hand carried the dynamite from the bunker and placed in the hole (arranged a circle of sandbags before bringing it out). Placed a block of C-4 wrapped with detonating cord next to the dynamite. Put a piece of plywood on the sandbags above the shot then 4 more thicknesses of sandbags. Ran the detonating cord out - attached a blasting cap/time fuse/igniter assembly - pulled the ring and walked away. Very effective. First time I was soaked from sweat - I’d done demolition before but NC with crystals was a different story. Second time I was more prepared and we used fewer sandbags. Some from the first detonation never disintegrated and were launched whole over the fence line.
What is called Military Dynamite is not related to commercial dynamite - it’s just TNT in wrapper / stick form; no NC.
years ago, I owned an ancient ranch in the middle of nowhere, 200 acres with 7 cabins loaded with antiques . 8 mile dirt driveway with 6 gates to get in, impassable in winter. There were boxes of dynamite, much of it between 50-95 years old. the original owners used it to blast giant boulders that rolled into the driveway periodically. When I sold it, I had to get rid of it. An old guy who did grading all over the mountain had handled dynamite for decades. He told me it was all myth, being unstable. It takes a major blast to activate it, bare minimum good blasting caps. I didn’t believe him but had hundreds of sticks to dispose of. most was covered in sweat, some stuck together, very scary to me.He came out and to prove his point, grabbed the sweatiest sticks, tore then from the bundle as I ran for a boulder to hide behind. He took two stick and snapped them in half. he said black powder is dangerous, real dynamite has to be blasted to explode. He set several up and shot them with his rifle, and his pistol. nothing happened. He started a fire and threw them in it, they just burned hotter and different color. He threw the sticks at boulders, saying the old westerns were all fake, you can only explode dynamite by shooting it if you hit a blasting cap next to the dynamite, and you don’t have to worry about shaking it or it being sensitive, as he threw it around and ripped it up.
So we had some fun. There were many blasting caps. We hooked 3 sticks up to a wire and used his jeep battery to explode them. It was insanely loud. Even though we were in the middle of the wilderness, someone would hear it somewhere. We took 4 sticks and threw them in the pond and used the blasting caps. Unbelievable explosion, made a geyser, but the sound was muffled. We kept adding more, until our grand finale, with 40 sticks taped together and 3 blasting caps. We touched the leads to the battery…the ground literally shook, knocked us both off our feet, two windows shattered in the closest cabin, and the entire pond recede like slow motion, then erupted 40’ into the air, raining the whole pond for thousands of yards. An old tree on the hillside fell. It was incredible. the ultimate playing with firecrackers. I went on this thread to see if the info had changed in this many years, when we did it I had no google, juts old books. Apparently the info is still misleading . He told me that was no accident, the authorities want you to report all dynamite found in old mines and sheds so they can account for it, not because it is imminently dangerous. Unless you somehow blow it up, it is pretty harmless. Thats just reality. The rest is myth. I was there, I saw it and eventually did it myself, got very comfortable with it. But I didn’t leave any , as the land was being transferred into national forest, and I sure didn’t want to bring any with me. But it was a helluva day.
My grandmother’s father used to dig wells and graves, and used dynamite when he hit rock. My grandmother once casually mentioned that he had buried a jar full of dynamite is a certain spot in the yard. If her memories were right, there is a jar of 60 or so year old dynamite still there (in a spot I walk by, possibly even over, pretty much every day.)
