From: kempmp@phoenix.oulu.fi (Petri Pihko)
Newsgroups: rec.pyrotechnics
Subject: Re: Salutes
Date: 11 Apr 92 22:15:44 GMT
Organization: University of Oulu, Finland

mingos@vax.oxford.ac.uk writes:
> In article <1992Apr1.152914.12142@cbnewsk.cb.att.com>, firebird@cbnewsk.cb.att.com (larry rosen) writes:
 > 
>  Mixing metal powders and a chlorate is NOT recommended, unless you want the 
> mixture to go off for little or no reason at any point.

This is a clear overstatement. Although dangerous to mix and use, the Chinese
employ compositions containing fine aluminium, sulfur and potassium chlorate
even today in some firecrackers and salutes. Shimizu also mentions such a 
mix without any warning about unexpectable behaviour. Don't get me wrong -
it _is_ dangerous to use chlorate-based flash powders, and I would always
recommend potassium perchlorate as a substitute for the chlorate, but metal
powders and chlorates _can_ be mixed relatively safely without any danger
of spontaneous ignition (as opposed to accidental ignition).

"To err on the safe side" should not mean "To exaggerate the danger".
Laboratory safety manuals in their search for ultimate safety in labs
quite often group all potentially pyrotechnic reactions (ie, all reactions
involving common oxidisers and flammable substances) into one category:
flammable/explosive, capable of spontaneous ignition. I have NEVER heard of
black powder or modern safety matches igniting spontaneously. 

Why shouldn't we exaggerate to improve safety? The main reason is that
nobody would know where to draw the line. If all safety warnings were just
overstatements, many people would start experimenting on their own to find
out what the truth is. That's exactly what I did at the time I had only a
few lab safety manuals and no pyrotechnic literature to rely on. The manuals
warned that red phosphorus is extremely dangerous when mixed with potassium
chlorate or other oxidisers. Roughly the same was said about sulfur. What
I did know was that sulfur can be safely mixed with  potassium 
nitrate. What I didn't know was that red P and potassium chlorate behaves
really unpredictably - until a friend of mine severely cut his right palm
in an accident. (He had luck; no permanent injury. ;-) )

 - aluminium works well as a waterfall composition (i.e. place in
> tube, and tether the tube horizontally well off the ground.  For a flash/noise 
> composition, use a 66:34or a 70:30 mixture of perchlorate:Aluminium powder 
> (this assumes you've gotvery fine Al powder) These mixtures are not so easy to
> light, and are best primed with a little black powder
>   Although these compositions are safer than the corresponding chlorate mixes, 
> they should still be treated with respect.

Very true. I recommend using a wooden cup for mixing and cotton clothing. 
Fine aluminium is sensitive to static charges. At least do not use plastic.


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       ' *' .* '*    SF-90650 OULU  kempp@           the Game.
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