Sciencemadness Discussion Board

Booster charge case

Ral123 - 25-6-2013 at 19:53

I've had a little dispute about what should be the case of a booster charge. In my opinion thin and hard metal, thin glass, thin, brittle plastic. Also I've mixed energetic material with styrofoam and acetone. When it dried it became very nice caseless booster, not at very high density, it also could be repeatedly dropped from 1m.
Other people have no problem lifting up anfo with thick PVC or cartboard with some medium R.E. materials. In commercial devices the boosters are very often caseless and in contact with the secondary. For example are with pressed explosive, surrounded by cast of the same explosive.
What do you think is the answer?

Bot0nist - 26-6-2013 at 04:53

Reactivity between energetics could pose an issue in some instances, without a case. I also think having good contact and using a casing material that wont "ballon" out and make a bit of distance from the main charge is less of an issue with a medium to large booster, than it is with a caps casing. Placment in the charge surely matters though. A film canister of dense TNP seems to do the trick every time...

Ral123 - 26-6-2013 at 05:22

Thank you for your opinion. Now I had in mind for example-main charge is 40g cast picric acid shaped charge with thick walled case and open top. Now I have the feeling that if I put 7g Tetryl on top with bottom of thin layer of duct tape and heavy walls of that booster, it will perform more reliably then let's say, medicine bottle with thick plastic.
But I agree, if it would be a large anfo charge with good confinement, film cans, medicine bottles, syringes will work. However if I have to use the cheapest way, it would be 50g EGDN based jelly and a cap No8.

Simbani - 26-6-2013 at 06:30

IMHO glass vials offer the most advantages for the home-experimenter, they are:
-unreactive towards every known energetic
-good conductors of heat, so it´s easy to cast stuff in there
-available for virtually everyone
-thin walled and they yield no far-reaching fragmentation- 15m away there is no danger of flying fragments
-they come in various sizes with a lid :D

golfpro - 26-6-2013 at 12:36

When you cap a booster charge, you do so right before you are going to detonate it, so if you cast etn or TNP, you would want to make a mold using the case of the blasting cap so there is a slot for the cap when it hardens right? Is this the same using pressed ETN? I don't think anyone wants to walk around with a capped booster of 30g. Also, does etn need a case of any sturdiness? I used to think that in order for a blasting cap to work, there has to be a firm case surrounding the main explosive so that the shockwave from the cap can compress it. Or is a blasting cap alone enough to detonate whatever it is (ETN) regardless of the container, say a siran sandwich bag.

Ral123 - 26-6-2013 at 13:24

But but... every cast explosive requires a booster...
Glass is excellent, but it leaves the delicate energetic exposed to nasty UV from the sun. It can also brake. For me it's the booster of choice so far, but I plan to try those copper pipe fittings. I guess they can be stuffed with TNP. I may try to detonate one metal cased booster, warped with iron wire to see the fragmentation, but I guess nobody will tolerate such test.

golfpro - 26-6-2013 at 14:20

Not really, 13g cast etn video, I doubt any booster there.

Bot0nist - 26-6-2013 at 17:49

13g of cast ETN is a booster...
And no, a charge doesnt always have to have confinment for compression. A sack of AN/PS/AL will kick off. The material can not move away from the caps exsplosion fast enough, there for it still compresses.Confinment does matter though.
The casing of the cap matters too. You want something hard and brittle, so that the force is applied to the surrounding charge. A softer metel will kind of "balloon" out and make a small seperation between the cap's casing and the charge right at the moment of initiation. This weakens the caps ability to reliably initiate.

Fantasma4500 - 27-6-2013 at 14:37

Quote: Originally posted by golfpro  
I used to think that in order for a blasting cap to work, there has to be a firm case surrounding the main explosive so that the shockwave from the cap can compress it. Or is a blasting cap alone enough to detonate whatever it is (ETN) regardless of the container, say a siran sandwich bag.


not really, in commercial blasting caps theres used 10:90 lead styphnate:PETN and im pretty well sure that theyre in full contact, both packed in the same aluminium tube

also.. if the reactivity of the TNP wouldnt make a problem ive seen a youtuber (vvideodemolitions??) anyways the guy that has farm and has done tests on all possible exotics, hes on SM aswell, he used a balloon and stuffed the secondary in, pressed it in through a funnel, you could insert a initiator in that, otherwise a simple plastic bag could be used to seperature it
(dont know if you would like to hear more detail on how that is done..? :D)