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Comment by Vladimof | Hacker News Reader

> (obviously they aren't going to give us step by step instructions).

nitrocellulose is very simple to make and detonate... and is also very stable.... I don't see why we need secrets... I played with that stuff when I was a teenager

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When I was in college in Toronto in 1961 there was a surplus store. All manner of WW2 radios etc. I looked at one pile and it was about 15 rolls of primacord. This was a long 5/16 hollow tube of vinyl filled with pure TNT. It resembled rope = rope pile/ $3/roll of 100 feet. 2/$5. I knew what it was, so bought it all. it being worth $25-30/roll/ I was an Engineering stoont and Russia had just set of their Czar bomba. We engineers had a group called the BFC(Brute Force Committee), so we had to have a bomb for Skule Nite. In the quad we set off about a quarter pound of this prima cord with a lighted fuse detonator. We paced off a 100 meter circle for crowd control and Mr Riggs set it off. Prima cord has a hugely fast rate of propagation of the detonation wave, so we heard an intense CRACK, not a boom with a few tens of milliseconds, but a true faster than sound detonation wave. No harm was done as had just set of the Skule cannon which alerted people to cover their ears. I explored these rolls with playing with the Monroe effect, A nice shapely rabbit hole. https://en.wikipedia.org/wiki/Shaped_charge

I stamped initials in steel beams etc. Hardest thing was getting detonators = well controlled. Never tried to make a tank buster.

Active surplus?

Hercules Sales = sold Surplus on Yonge at Wellesley. The strip around there had Electro Sonic, Radio Trade Supply, Paramount Equipment and 2-3 small surplus and parts sellers. When transistor came along, radios never broke, TV's never broke and the parts and surplus ecosystem went away. Efrem Kohn came from Israel in the mid 60's and his Uncle Frank and Peter Eben who owned Active Machinery gave Efrem(Freddie) one of their store fronts = Active Surplus. He carried on until Queen W got gentrified and electronics from Taiwan and later China totally swamped Canadian electronics = all died off = no more surplus. The surface mount assembly also made parts salvage by hobbyists a waste for most people. Now there are only Creatron and one other place on College. I had 7 stores in 1985, closed the last in 2002. I was Parts Galore, a few remember me at trade shows, but I went into mining in 1995 and sold my company in 2018 and retired.

Super interesting, thank you for the backstory. I lived in Toronto from 1998 to 2003 and spent quite a bit time roaming around the dustier parts of AS.

Fond memories!

Yes, thanks. The Toronto surplus area was minuscule compared to Canal STreet in New York city in the 50's and low 60's. You might find some rabbit holes on google of the old days?.

Rabbit holes for NY and Radio Row

https://gothamist.com/arts-entertainment/the-history-of-radi...

https://www.nytimes.com/1987/10/29/garden/shopping-canal-st-...

nitrocellulose isn't necessarily very stable. If it's an amateur making gun cotton there's always the risk that they won't properly wash out the acid and if there's enough left, when left to dry the evaporation of the water can concentrate the remaining acid enough to cause spontaneous combustion. Other than that it's pretty stable but worth pointing out that film used to use nitrocellulose as the base material and there's tons of movie theatres that burned down in those days and even just vaults storing the film under ambient conditions. As the nitrocellulose decays, it can release nitric acid, thus accelerating the decay and potentially starting a fire.

If properly prepared and used and stored responsibly then gun cotton can be safe, even when used for teenage antics. Lighting off a piece while resting it on an open palm of course being one classic trick with nitrocellulose. I'd say storage and transportation of low and high explosives are some of the riskiest aspects because there's so many insidious ways for it to go wrong that you wouldn't learn about until you need to take your shoes off to count past 7. It doesn't help that nowadays it's so trivial to find out how to synthesize acetone peroxide and storing it long term is always going to be fraught with peril. Especially when someone without any semblance of proper containers stores it sealed up in a plastic bottle with a screw on cap. Just one drop or one crumb of primary explosive on the screw threads and maybe you get it sealed up, but when it dries out in the threads there's a good chance it goes off in your closed up hand when you try to open it and add in all the friction rubbing between the threads.

I assume it helps to narrow down the list of suspects if/when the (guarded/secret) knowledge is used for nefarious purposes.

Nitrocellulose is not a high-order explosive and used nowhere in this experiment. Deflagration != detonation.

Is that what they are using for the acceleration charge (not the main charge!)?

It is not. Nitroglycerin doesn't have the capacity to detonate (necessary for triggering the main charge). Detonators (the acceleration charge you mention) are usually an explosive train starting with a sensitive primary like lead azide moving up to a secondary or pseudosecondary output charge like PETN.

Oh man lol. Nitroglycerin most certainly has the power to initiate even a insensitive explosive like RDX, PETN, etc. It's detonation velocity is ~ 7700m/s. It's just very unstable which is why it isn't used raw. A jostle or turning the stopper on the bottle it's in can set it off. The less pure it is, the more dangerous it is. It's detonation velocity is twice as high as lead azide for instance.

Nitrocellulose can also be detonated with a properly brisant primary charge, which nitroglycerin is quite capable of being.

Typically Nitrocellulose (aka gun cotton, and the primary ingredient in most smokeless powders) won't detonate on it's own, but it's a very different beast from nitroglycerin.

[https://en.wikipedia.org/wiki/Table_of_explosive_detonation_...]

GP's comment was referencing nitrocellulose, which is what I was attempting to address but fatfingered to 'nitroglycerin'. Forgive the typo.

The diagram shows a detonator and an acceleration charge. That's why I was wondering what the acceleration charge was.

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