65 replies to this topic

[cunning_plan]

a profesionals guide to pyrotechnics. john donner.

had it kying round so thought id have a look.

To which book do you refer?

[Richard H]

Not the most reputable of works!

[alany]

The problem with chlorate and sulfur is a fundamental chemical incompatibility, sulfur oxides/sulfuric acid have a catalytic effect on chlorate decomposition, releasing chlorine dioxide and oxygen which react with sulfur and produce more sulfur oxides, heat, etc. Chlorine dioxide is a powerful and unstable oxidising agent, it decomposes explosively with little provication making it even easier for a unstoppable chain reaction occuring.

It is rather like a rock on a cliff edge, it doesn't take much energy to start a run-away reaction. However there are a few ways to make the edge of the cliff a litte harder to get over. The buffering in the cap compositions you've read about soaks up the sulfur oxides/acid as it forms. It isn't 100% effective of course, it can be locally overcome when the composition is struck/scratched/heated, it is just effective in keeping the natural oxidisation of the sulfur at bay for many years.

A single crystal of Potassium Chlorate can detonate, in the true sense of the word. Potassium Chlorate decomposition isn't very exothermic, so the reaction is very hard to initiate and difficult to self sustain, crushed powder is not really dense enough to propagate the shock front, however if even small amounts of a fuel are added the released oxygen burns it and can overcome the losses and sustain a detonating front through a pellet of composition. Sulfur just makes a wonderful fuel for this process (Phosphorus is even better), which you should find pretty scary, bulk chlorate with relatively low contamination can explode with appreciable violence. Torpedeo cane compositions use this principle and no buffering in the world will help.

[cunning_plan]

alany- cheers that realy helps a lot. I did not buy the book as i could think of many better ones, it was in my school libary! so i thought may aswel have a look. I take it this means its wrong. luky i had this thread before the book! cheers all

[Old1953]

According to this page:

http://www.geocities...ate/safety.html

The instability is largely due to temp changes and polythionic acid. They ran tests.

And a drop hammer test is pretty much a standard for sensitivity to impact. How else would you determine impact sensitivity?

So, a question, do you think this thermalite fuse formula is safe or not, given the metal component?

http://www.wecreate4...thermalite.html

Edited by Old1953, 01 March 2005 - 02:50 AM.

[karlfoxman]

hey guys,

i have had some potassium chlorate around for a while and am trying to think of a good use for it. i want to break some shells harder and H3 burst is my option. i dont like flash/whistle and cant get potassium perchlorate. is this a wise choice? (i know the sulpur/chlorate DEATHWISH) how do i mix it with the charcoal?

regards

karl

[alany]

Pre-mill the potassium chlorate and the charcoal seperately then screen them together gently. Roll onto hulls in much the same way as you would BP or KP, but it is a good idea to have a dedicated roller bucket for H3 - probably paranoid if you wash a smooth bowl roller carefully but it can't hurt especially if you roller has corners that can hold stuff. It can be granulated pulverone style for salutes and small shells.

H3 is not all that sensitive alone (Shimizu calls it "quite unexpectedly insensitive"), some argue than KP is more sensitive to friction and Shimizu has done a range of tests that suggest this might be correct. However if it gets contaminated - well all bets are off. Real H3 is specific to Hemp charcoal, which is fairly high in ash but extremely reactive, you might need to tune the charcoal content slightly with commercial airfloat or some other charcoal if you want the best performance, but H3 is pretty damn fast no matter how poorly you make it.

The real issue is if you have the lab space and tools to dedicate to chlorate use for best safety. At the very least you should dedicate a meda set and jar to milling chlorates and a 40 mesh *stainless steel* sieve and camel hair brush (if you use one) with a non-metal ferrule, non-steel at least, preferbably not brass either. Storage is an issue too.

(edit)

Old1953: Thermalite is well known for igniting while being cut and burning up the whole roll before you can drop it, especially the fast stuff. Its an accident waiting to happen IMO, especially for cross-matchting and crossettes. If I used it I'd cut it outside with a good foot off the roll to the cutting point so I had a chance to drop it before I got cooked. You have to wonder if sulfur contaminated shears are the cause for some of the accidents though.

You can probably strike thermalite on a match box? Never tried through. Dan's version (from Firefox FX) looks relatively tame, the plastised binder probably makes it somewhat safer. Still, I can't see any reason to use such sensitive and chemically incompatible fuse, I prefer blackmatch and appropriate priming where required.

I feel a little uneasy when I cut through my zinc match, even blackmatch at times. No matter what kind of match it is I always cut it away from a device and the bundle of match I took it from. I guess I am paranoid, but I can't imagine what a few hundred feet of match inside a postal tube would go up like, and I have no desire to find out first hand.

Edited by alany, 03 March 2005 - 04:21 AM.

[karlfoxman]

thanks for the super info alany,

i already have seperate milling media for chlorate, i am so careful when it comes to using the stuff, i will be making my shells using clorate for the stars and the burst. i found a good zinc/chlorate star mixture, pale green. i will mix up the h3 burst this afternoon. will make some pulverone vs fast willow bp small shells and shoot them tonight if i can get it to dry quickly

thanks again alany

karl

[chrissw]

Ok first off im new on the formums so hi all.

i am quite(6 months) new to pyro but can already see many angry faces to this question...
is potassium chlorate that bad to use as a replacment to potassium nitrate in bp? it seems to work fine for me and is much easyer, it is also a lot cheaper only issues is everywhere seems to say not to use it especialy not with sulphur. ive so far had no problems, it is only sensitive if i hit a pile of it with a hammer and i havent been storing it. as there seems to be loads of conflicting info on this everywhere i decided somone here would most likely no if it is safe to use? i would by perc but i can only find it realy expensive so...also which is a better for use as oxidiser in propellants nitrate or chlorate.
sorry to bring this issue up again i just wanted a realy clear answer.

You can try belting it with a hammer if you insist, however, let me know where and when you intent starting the experiment, so I can be somewhere else when it finishes you!!!!!!!

[Old1953]

I feel a little uneasy when I cut through my zinc match, even blackmatch at times.  No matter what kind of match it is I always cut it away from a device and the bundle of match I took it from.  I guess I am paranoid, but I can't imagine what a few hundred feet of match inside a postal tube would go up like, and I have no desire to find out first hand.

Probably like a very active fountain, and I'd expect a lot of still burning junk to fly out the end of the tube. A fuse mine perhaps?

I wonder just what incompatabilities are lurking in the visco fuse. I've never seen any statement of just what they put in those for oxidizer or fuel, but it isn't simple, at least not in the colored fuses.

[Phoenix]

I believe I have read that some visco fuse contains a perchlorate mixture that is compatable with chlorates. When using commercial fireworks, you will notice that some visco fuses burn much more fiercely than others. I suspect that the more energetic ones contain the perchlorate mix, whereas the gentler burning ones contain (sulphurless?) black powder.

[alany]

Yeah I've heard that too, but the only visco I've ever seen is chinese stuff. It smells strongly of sulfur, don't need to even bother testing for it. A quick qualitative test for perchlorate would tell you for sure, Methylene blue would do the trick, but you'd have to do the test carefully in case it has mixed nitrate/perchlorate oxidiser.

Crystal growth patterns on a glass slide will tell you pretty quickly too.

[cunning_plan]

a few queries. firstly is visco compatible with chlorates? it sounds a stupid question i know but your all mentioning it having sulpher in it so...

also if i remember correctly i got a warn level and blazed by quite a few people for saying i hit some chlorate bp with a hammer to test if it was as shock sensitive as i thought.

earlier post

i was going to try some basic chlorate stars. anyone fancie suggesting what to try first?

[Old1953]

a few queries. firstly is visco compatible with chlorates? it sounds a stupid question i know but your all mentioning it having sulpher in it so...

also if i remember correctly i got a warn level and blazed by quite a few people for saying i hit some chlorate bp with a hammer to test if it was as shock sensitive as i thought.

earlier post

i was going to try some basic chlorate stars. anyone fancie suggesting what to try first?

A drop hammer test is a bit more than just whanging at a pile of comp with a hammer. I suppose there is an ASTM for explosive mixtures sensitivity testing, but I don't have it.

Now the ASTM dealing with coal, coke and gas, that I had memorized at one time of my life.

A full set of old ASTM manuals would be worth its weight in gold to many of us, because the tests are often reproductions of industrial processes on a very small scale.

This pdf has some info on standard drop hammer testing.

http://www.kuhner.co...NT/b033_023.pdf

Edited by Old1953, 14 March 2005 - 08:38 PM.

[Phoenix]

i was going to try some basic chlorate stars. anyone fancie suggesting what to try first?

I'd suggest that you try something other than chlorate stars to start with. Stick to to nitrate based stars for the time being. Charcoal streamers are good, and reasonably safe. Want something else? You can make good white stars from the same ingredients, in different proportions. The formula on Paul's site works very well.

Before you start using chlorates, I would strongly advise you to read T.I.F. 10 by Bill Ofca, available at http://www.skylighte.../mall/books.asp - It's about 3/4 of the way down. This book contains several well tested formulas, and will not cost you very much. The total is about ?20.00 at the time of writing, although I admit that it's less than Skylighter's minimum order, so you'd have to get something else too. I'd consider that a good thing