20 replies to this topic

[BigBang]

Hi guys, i have 2 questions. Ive been happily making flash using KMnO4 for about 25 years now, but finally decided to 'conform' and use KClO4. After months of trying, i finally managed to get hold of some, mixed up a 1gram batch of 7:3 flash, and i barely managed to ignite it! when i did, i just got a bright slow fizz, about the same as one would expect using KNO3. The addition of a small amount of sulphur made it burn slightly faster, but still, it was next to useless as flash. The KClO4 was supplied by the manufacturer with a certificate of analysis, so it is the genuine artical. I noticed it had anti-caking agent (Na2SO3C12H25) 1% added, but i cant imagine that would make any difference. So whats the problem? It definately isnt the Al i am using, as this is extremely reactive when mixed with KMnO4. Can anyone suggest what the problem may be???

Also, i found this demo:

http://www.mitglied....2010/keller.mpg

This is 1gram of 1.5micron flake Al & KClO4 flash. Is this typical of what i should expect? because i find that reaction pretty pathetic, compared to the flash i make using KMnO4. Thanks


Andy

[Richard H]

What aluminium are you using? Shape? Particle size? Coating?

[BigBang]

I have tried various different types, the finest being 3micron atomised, irregular shape particals, coated with 0.5% steric acid. When used with KMnO4 the reaction can only be described as explosive, so it cant be the Al, can it??

[Richard H]

I suspect it is the aluminium. Flash powders are made using flake particles of aluminium down to 5 or so microns in size. These powders burn so quickly that a small pile will often explode with a report unconfined.

I would avoid KMnO4 full stop. Since I have never used this material I cannot comment on it.

[BigBang]

I have tried it with german dark flake Al but got the same results, so its unlikely to be the Al.

Does KClO4 have a shelf life? maybe its gone 'off' is that possible?

[Richard H]

Not heard of anything like that myself. Are you using accurate scales? What particle size is the perc?

[sasman]

From what i have read i have seen no mention the KClO4 Degrades in storage?..If your Perc was supplied with a Certificate of anaylsis(assuming its from a proper company).. Then it must be your Al powder..

Dont forget just because your Al may burn very fast with KMNO4 that doesnt make your Al Dark german?..KMNO4 is a very powerfull + Dodgy Oxidiser...and even crappy Al powder burns very fast with it...But Crappy Al powder dont burn very good with Perc..

Also some where on this forum i posted my experience with a few grams of Flash and belive me its very scary stuff....

Altho you Must Have the Balls of a Bull ..To mess about with KMNO4 Flash...I out grew that stuff 25 years ago!!

[Andrew]

Just out of interest, where did you get hold of your perc??

[BigBang]

Sasman, you have hit the nail on the head! After using KMnO4 as the oxidiser, i was expecting similar results when using perc. BUT perc is nowhere near as strong an oxidiser. The Al i am using, although extremely fine, is not flake, but with the KMnO4 gives absolutely amazing results. I was expecting the same results with the perc. Oh well, you live and learn!

I have just tried the perc again with Ekhart dark Al, and the results were better but still nowhere near as good as with the KMnO4.

As for havin the 'balls of a bull' dont think the wife would agree with that

Seriously though, although the dangers of using KMnO4 are very real, they are exaggerated. As i said in my previous post, i (and several of my pyro friends)have been using it for over 25 years with no problems. Partly due to the fact that perc is so difficult to get hold of.

I actually got my perc from a company in China! Several of us got together and bought in bulk. It wasnt easy, we had to buy it through a friends company. I found it next to impossible to get any here, (unless you dont mind paying through the nose) and it wasnt through lack of trying, i can tell you! i dont think there is a company here i havnt called.


Andy

[Draco_Americanus]

could your perc have too much water in it? I have been told that this stuff is slightly hydroscopic and the supply I have clumps very badly but it does still react well when used with flash and with alumium that I am guessing is 25 micron dark stuff. It does not explode unconfined but it flashed very quickly, has a nice report with a paper tube though.
I got my perc from "kits and plans unlimited" for 9 bucks a pound.

I have not tried the kmno4 for flash yet, I have about 6 pounds of it but since a nasty coffie grinder fire I have not messed with it since and that was 11 years ago(Never trust some one to clean the grinder, do it your self that way only you are to blame for contamination )

[Mumbles]

Even with clumpy KClO4 I've never had it not preform satisfactorily. I have a large amount of clumpy KClO4, and it works just the same as my fine supply(once broken up of course).

I've only tried using KMnO4 a few times in flash powder, and I was never that thrilled with it. Perhaps BigBang had a better ratio than I. Actually, more than likely is that I was using inferior Al at this point in my experimentation. It my experiece the two don't even compare. KClO4 is better hands down. KMnO4 is however a stronger oxidiser and gives up it's oxygen at a lower temperature than KClO4. It is also more unstable than KClO4. These in combonation could lead to a better product. If I'm not mistaken, it also self confines at a lower weight than with KClO4 based flash. This is just testament to it being more unstable.

[Andrew]

permanganate also degrades over time, the right conditions can help prevent it's eventual transision to the nasty black stuff. Another testiment to it instability perhaps!

[al93535]

BigBang: I would say the video you posted is pretty typical. Although I have not seen that many bright sparks from my stuff. My flash always amazes me. Your flash puts that video clip to shame? Damn. Not getting good results can only have three causes: Bad KClO4, bad aluminum, or bad ratio. You know the KClO4 is good, and if you are using german dark you know thats good. It must be ratio's, or a bad scale.

[BigBang]

Andrew, it surprises me that you say that, because ive bought permanganate in quite large amounts in the past, and it can last me for years sometimes, without any degrigation......it must take many years to degrade then. I can remember one large batch i bought, i had for over 4 years without any fall in performance.
I dont disagree with you but i'll look this up and see if i can find out any facts

Regarding the comparison, as far as i am concerned the flash i make does put that video to shame. I use 5micron coated atomised Al powder (not even flake type) with KMnO4, and the report from just 1 gram, as in the video, completely unconfined would make your ears ring at 12feet and thats no exaggeration!! Ive been doing this for many many years now without a single 'incident'


Ive been experimenting with KClO4 for the past few months now, and i am not particularly happy with it. I find i get more misfires due to its higher ignition temperature, and lower report levels for the same weight of powder.

I'll agree that KMnO4 is not suitable for use in commercial fireworks, because of its instability, but for an experienced hobbyist like myself, who mixes in small quantities and uses within a few days, is far superior, IMHO.

[Andrew]

BigBang: I would say the video you posted is pretty typical. Although I have not seen that many bright sparks from my stuff. My flash always amazes me. Your flash puts that video clip to shame? Damn. Not getting good results can only have three causes: Bad KClO4, bad aluminum, or bad ratio. You know the KClO4 is good, and if you are using german dark you know thats good. It must be ratio's, or a bad scale.

Or bad mixing!