From: pjo@conan.cs.hut.fi (Pasi 'PJo' Jokela)
Newsgroups: rec.pyrotechnics
Subject: Re: flash recipes (& experiences & ANFO stuff)
Date: 7 Jan 93 00:00:02 GMT
Distribution: inet
Organization: Helsinki University of Technology, CS lab
NNTP-Posting-Host: conan.cs.hut.fi

In <1993Jan6.140846.22085@bernina.ethz.ch> brech@vision.ethz.ch (Christian Brechbuehler) writes:
>According to Shimizu, you get the loudest noise from a composition of
>64% KClO4, 23% Al, 13% S (by mass).  Note that a mixture containing
>sulfur is considerably more sensitive to friction, heat and probably
>to shock.  Therefore it is more dangerous.

>I've set off both mixtures (a) with a match, (b) by hitting them with
>a hammer, and (c) by friction between porcelain (china) surfaces.

 I've used KMnO4:Al:S (20:7:4).  It works OK.  Adding sulphur makes it
more sensitive, but I've placed a lighted match on top of a pile of
flash and it didn't go off.  Also lighting the paper under the flash
pile doesn't always set it off.

 Flash seems to be more difficult to set off that a black powder but
it is also more potent stuff.  I like it because it is very easy to
make.

>Conclusions:
>Flash is dangerous.  Use only minute amounts!

 The first time I used it was in a modified fire cracker.  I put ~10
grams of flash in it.  I didn't expect such an "improvement" from the
unmodified version and stood about 5 feet away from the cracker when
it went off (protected from the possible shrapnels though).  I just
heard the initial BOOM but none of the echoes, since my ears were
already ringing.  Fortunately the ringing only lasted for 30 seconds
or so.  Needless to say, I've treated flash powder with more respect
after this incident. :)  Putting 10g of flash in a plastic pipe (melted
shut from the ends) gives a real loud bang (and a shower of shrapnels!)
I've also tried it in a metal pipe, but even though the bang is much
louder it is also much more dangerous to manufacture and detonate.
With two steel pipe flash bombs (~15g) I polymorphed a paint can into
a sheet of metal with scary looking holes in it.  Having one of those
things go off in a hand would probably mean death or at least very serious
injury.  Just remember, if you're stupid enough to try it (I am!), at least
be smart enough to be verrrrrrry careful (I was!).

 Btw, we detonated ~5kg of ANFO in a iron sewer pipe (10cm/4" diameter)
awhile back.  This happened in a remote sand pit.  We were about 30 meters
(100 feet) away from the bomb (it was in a steep hill facing away from us)
and the boom was REALLY loud!  I had placed a car tire on top of the bomb
and afterwards I found pieces of it at least 50m away.  The pipe itself
must have broken apart into hundreds or thousands of small shrapnels
judging from the two pieces we found and the damage caused to the nearby
coppice forest.  Thoughts of what this kind of device would cause in
a crowded mall or a subway station belong to alt.tasteless. :)  I think
our next "project" is to detonate similar amount under water.  Someone
with experience could give hints.  We want to get nice pillar of water. :)
The event would take place in a smallish (~50ft diameter) pond.  I don't
know how deep it is yet.

 Also, I'm looking for a way to cause as loud sound as possible with
smallest possible risk to living creatures around the detonation site.
Motto: the bigger the boom, the better I like it. :)

 Finally, I have a question to my countrymen (Finns).  Rest of you can
skip this section.  (It is in Finnish..;)

 Haluaisin tietoa Oulun salpietarin k{yt|st{ ANFOssa!  Erityisesti
kokemusper{inen tieto olisi arvokasta.  Jos on jotain muita vaihto-
ehtoja, haluaisin kuulla niist{kin (tied{n jo, ett{ kylm{pusseista
saa ammoniumnitraattia, mutta se tapa tulee aika kalliiksi).  Joo,
ja jollakulla on ylim{{r{isi{ (s{hk|/tulilanka)nalleja, niin voisin
olla kiinnostunut.  (Hyss...:)

 Okay, that's it.  Mail/follow-up/comment/flame(dangerous!!;)/whatever..

	    PJo

--
Pasi 'PJo' Jokela - Pasi.Jokela@hut.fi - pjo@vipunen.hut.fi - PJo on IRC
              This is the essence, the death of your soul.
             Elevate your mind, let your body take control.
V'z ebg-13 ivehf. V znxr crbcyr ebg. Pbcl zr gb lbhe .fvt gb vasrpg vg!!
Newsgroups: rec.pyrotechnics