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KClO3 and sulfur general compatibility

potassium chlorate sulfur stability compatibility

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#1 JTO

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Posted 14 September 2021 - 05:38 AM

It is said that one should never use both in the same composition, but in pyrodata.com there are EIGHT star compositions, ELEVEN burst/report compositions and ELEVEN flash compositions which contain both substances. How is it possible, or is the whole compatibility issue a myth?

 

I recall that match heads contain both substances and I've never heard of a match box spontaneously igniting. Moreover they are often kept in high temperature, for example close to a fireplace, and they do not ignite.

https://pyrodata.com...scription_1=All

 

https://pyrodata.com...scription_1=All

 

https://pyrodata.com...scription_1=All

 



#2 Arw

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Posted 14 September 2021 - 09:11 AM

Risk has different level and You choose that what you give and what you get my friend.


Edited by Arw, 14 September 2021 - 09:11 AM.


#3 mabuse00

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Posted 16 September 2021 - 08:15 AM

There are a lot of antique formulas in such compilations, imho added for the sake of completeness.
In most cases they do not offer any advantage over more modern non-chlorate ones.

You simply do not need them.

In fact, you do not need chlorate at all, apart from a few niche applications.
The only reason to use it is either you happen to have it or you make it yourself.
Especially when you live in a political environment where you cannot get perchlorate.

"Incompatible" can mean several things, from "ignites by itself" (in the past sulphur often contained traces of acid) to "unnecessary sensitive, but usable".

 


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#4 SeaMonkey

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Posted 16 September 2021 - 11:58 PM

Here is an interesting video from about 4 and 1/2 years ago where the Friction Sensitivity of various proportions of Potassium Chlorate and Sulfur were tested.


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#5 Crazy Swede

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Posted 17 September 2021 - 12:52 AM

It is all about pH!

 

If your sulfur is non acidic and your composition has some kind of pH buffer, like MgO, it will be stable for storage. Still very sensitive to friction but it will not spontaneously ignite


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#6 Arthur

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Posted 17 September 2021 - 03:41 AM

The issues are not always the indicated elements, BUT the impurities associated with their various methods of manufacture over the last hundreds of years.

 

In prior centuries sulphur was found and mined naturally but it contained significant traces of acid which was enough to trigger reactions. Modern sulphur comes from oil refining as a by product of making extra low sulphur road, marine and aviation fuels.

 

However, nothing has ever been said to be dangerous without reason, especially in an industry that makes inflammable things. While old formulae had lots of chlorate and sulphur compounds -because they worked- the comps lead to products that didn't store well or could be sensitised by humidity cycles. As a result of some serious spontaneous explosions in England work rounds to avoid chlorate/sulphur comps were developed leading to the development of perchlorates and leading to the pre-washing of sulphur.

 

Nowadays there is very little reason to use chlorates -they increase sensitivity, or chlorate/sulphur  comps -due to their sensitivity. Where there really is a need for chlorates is some sensitive products like old primers and some cool burn comps like smokes. For good reasons professional pyro manufacture minimises the use of chlorates to minimise the risk from chlorate comps and from cross contamination. 



#7 sefrez

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Posted 17 September 2021 - 10:06 PM

I hate chlorates with regards to accepted "incompatibilities", of which I abide to the best of my knowledge in pyrotechnic devices, but I love them because they are easier to make than perchlorates and work better (in my experience.) Decent colors can be achieved without metals and using less chlorine donor. They also ignite easier and don't go out as easily, again in my experience. This goes along with its higher sensitivity compared with the other oxidizers.

 

Though I have done some tests with chlorates to find conditions seeming to be specific for an accident to happen. Although these test suggest to me the sensitivity of chlorates as claimed by the general community are a little exaggerated, I still choose to take those claims seriously because any conclusion I come to on the contrary need stand tall against the vast dealings with chlorates giving them a "bad name."

 

On small scale, I have mixed stoichiometric amounts potassium chlorate and sulfur (according to 2KClO3 + 3S -> 2KCl + 3SO2) and added drops of ~80% sulfuric acid to it. Upon doing so, I observed much heat produced and redox reactions from the gases being released. Sulfur dioxide was definitely present by scent, but I imagine chlorine and chlorine dioxide were also being produced. I thought for sure the mixture would ignite, but it just simmered down and I neutralized the acid to end the test. Its been a while since I did this test and can't remember how much acid I added to the composition, but its possible I added enough that it actually diluted the composition which could of possibly had the effect of preventing the above reaction from ultimately taking place.

 

I added the same acid to a small amount of H3, and that was a very violent reaction. I would have guessed it the other way around. I didn't do a test on a mixture containing all three (oxidizer, sulfur and charcoal.)

 

I did try ~30% HCl on H3 as well. It mostly produced Cl2 and ClO2. Not much heat and no ignition.

 

All that said, I still keep the acids or acid forming compounds far.....far.... away from chemicals ready for pyrotechnic usage. Oh, and ammonia or ammonium compounds.



#8 SeaMonkey

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Posted Yesterday, 12:14 AM

Interesting account of your dripping concentrated Sulfuric Acid onto various Chlorate mixtures.

 

The one mix which will inflame by adding a drop of Sulfuric acid is the Chlorate-Sugar mix.

 

Whether 80% Sulfuric Acid will ignite the mix reliably I cannot say.

 

But the 80% can be concentrated to about 93% quite easily.



#9 Arthur

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Posted Yesterday, 08:25 AM

Remember that chlorate was the essential ingredient for colour comps for years (and some others). It wasn't an option it was essential. However since the advent of perc which is far safer there is little need to use chlorate. While the incompatibilities of chlorate are known and some are more hazardous than others it's always easy to look for a more stable alternative, usually there is one, just occasionally there is no choice.


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