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Author: Subject: Flash Powder
Blaster
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[*] posted on 1-9-2004 at 09:09
Flash Powder


Here's a simple recipe for flash powder I've been using for years. In fact I can attribute my interest in explosives and even chemistry to it because it is so versatile.

By volume: potassium permanganate 2 parts, Aluminium powder (the finest flour-like grade) 1 part, powdered sulphur 0.5 part.

To prepare, grind the KMnO4 to the finest possible powder in a mortar. You know when you've ground it enough when it changes in colour from dark purple to a lighter purple.
Clean the mortar then mix the Al powder and sulphur together.
Finally add the KMnO4 and mix gently, do NOT grind!

This composition will burn much faster and hotter than black powder and is vastly superior for making cannon crackers or any firework requiring an explosive charge. It explodes without fail when confined in any way (if prepared as above).

However this composition has an even better property, namely it can be ignited by adding a drop of glycerine. This reacts with the KMnO4 and gets so hot it ignites the mixture.
The mixture usually takes around 20 seconds to ignite depending on ambient temperature.

This is great for setting off a sequence of explosions without using a flame - simply add a drop of glycerine to each charge.

Alternatively, place the flash powder in a container with a screw-on lid. Add the glycerine and QUICKLY tighten the lid before throwing into water - hey presto an UNDERWATER explosive.

Here's a demo:

Flash powder and eye dropper full of glycerine.



Add a drop of glycerine.



20 seconds later (bit too close to the Porsche for comfort!)

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chemoleo
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[*] posted on 1-9-2004 at 10:11


Nice pictures.
I didn't know of that mixture... but tsts - making perchloric acid esters but yet measuring powders by volume? :P Have you tried to find out whehter parts by volume arrive at stoichiometric quantities?

Anyway, please be reminded that this is a forum that doesn't focus on practical discussion of explosives/pyrotechnics - unless it is in some way unusual (i.e. not the bog-standard AP, or NG, or blackpowder) - as this has been discussed in depth in other forums (and this thread is a borderline case... )
So let's keep this thread to unusual mixes - no discussion of your latest BP /chlorate flash experiments. Let's see where this gets us - it can always be closed later... (unless other mods/admins object anyway :()

[Edited on 1-9-2004 by chemoleo]




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[*] posted on 1-9-2004 at 10:23


I've tested several flash powders and I use only those : (in mass)

3KMnO4 + 2Al + 1S which burns really fast and is really easy to explode (even in a opened cardboard tube !!!) But it is very sensitive...

3Ba(NO3)2 + Al + 0.5S which is more stable compared to the KMnO4 one

I hope this will help you =)

Edit : Funny Thing : when the mixture has burn just add water, smell the H2S it's nice ;)

[Edited on 1-9-2004 by sylla]
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Blaster
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[*] posted on 1-9-2004 at 11:03


Chemoleo - I'm aware of the practical side but thought the glycerine aspect would be of interest and, as you say, not the usual acetone peroxide (yawn) or black powder stuff.

As I'm sure you know, the products of combustion of such mixtures is not an exact science making weights purely theoretical, hence the use of volume.
I actually mixed BaClO4 and BaETSO4 by volume not weight too when making the perchlorate esters (50:50)!

[Edited on 1-9-2004 by Blaster]
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[*] posted on 1-9-2004 at 12:34


Quote:
Originally posted by Blaster
As I'm sure you know, the products of combustion of such mixtures is not an exact science making weights purely theoretical, hence the use of volume.


EH?

Perhaps I am mistaken, but I am labouring under the impression that the study of the combustion products would be an exact science, if it were done using the scientific method (and exact weights and measures).




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MadHatter
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[*] posted on 1-9-2004 at 13:36
Al Powder


Blaster, out of curiosity, what was the mesh and/or micron size of your
Al powder ? I'm curious because I like making my own Al powder for various
flash and rocket mixes.




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Blaster
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[*] posted on 1-9-2004 at 13:37


Not so! Mixtures such as this produce a multitude of products because of the way the powder is mixed. Whole scientific papers have been written on the products of combustion of black powder.

It is physically impossible to ensure, for example, that one molecule of KMnO4 is adjacent to an Al atom or an S2 molecule. No matter how fine it is ground there will always be accumulations of the various components.

Additionally, and as a direct consequence of this, multiple oxidation states of the manganese and sulphur are produced dependant on how and with what they react. This I have observed in a simple way by setting the mixture off on snow - purple unreacted KMnO4 stains the snow, along with green K2MnO4, fully reduced black MnO2 and others. Similarly SO2 is produced and H2S (it can be smelt despite hydrogen not being theoretically in the mixture as mentioned by Sylla). This is not to mention other products such as MnSO4, Al2(SO4)3, Al2S3, O2, Al2O3, K2SO4 etc, etc. Look at the cloud of smoke - a brown mass of who knows what!

Therefore it is impossible to exactly determine the quantities of reactant required. The best that can be done is an approximation.

[Edited on 1-9-2004 by Blaster]
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[*] posted on 1-9-2004 at 13:49


MadHatter - I've just checked my bottle of Al powder (its ancient) and it does not quote the mesh size.
It has the consistency of flour however.

If anyone has a method of preparation of extremely fine powder like this (where individual grains are too small to be seen by eye) I'd be very interested to hear it.
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[*] posted on 2-9-2004 at 01:16


I'll guess I'll leave this one open since it's still on a chemistry tangent.

Although this KMnO4/Al/S flashpowder is nothing new, was my first flashpowder that I made in fact.

Do keep it away from water or oxidizable solvents (including acetone) though! :o

KMnO4 + 50 micron Mg is yet another story...:D




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[*] posted on 2-9-2004 at 10:15


I've tried this flash before it was not so succesful as i didn't grind the ingredients. This method for preparing flash powder remindes me of my method for preparing black powder. You'll find the post in the Detritus section. BTW love the Porsche. Is it your's.......?
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[*] posted on 2-9-2004 at 11:59
Nice Porsche


Love the car.
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[*] posted on 2-9-2004 at 14:08


I would have thought that powdered Mg would make a good flash powder, or component of same. It is more easily ignitable than Al.

John E.
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[*] posted on 2-9-2004 at 14:52


Dodoman - you didn't grind the ingredients?!!! Tut, tut, the number one rule of firework preparation is fine grinding.

Car - thanks but its off topic!

JohnWW - Mg does make a good flash powder its true. However, I have never come across Mg powder that is as fine as the Al powder commercially available (perhaps its too reactive to be stored and sold when extremely fine) and consequently the burn speed cannot match the Al variant.
Ignition is definately not a problem with the Al mixture with a permanganate oxidant! However, if potassium dichromate is used instead, ignition is difficult and that's where Mg comes into its own.

As an aside - try adding lumps of calcium metal to the mixture for red jets.

[Edited on 2-9-2004 by Blaster]
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[*] posted on 3-9-2004 at 05:00
mg powder


If you played with high powered rockets you would have 1000 mesh mg amongst your supplies works great in place of aluminium powder.
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[*] posted on 3-9-2004 at 12:14


Quote:
Originally posted by Blaster
Tut, tut, the number one rule of firework preparation is fine grinding.


[Edited on 2-9-2004 by Blaster]


I know that Blaster. Well anyway i wanted to give it another go so this time i used your method. It burns very slowly in fire and when ignited with glycerine; it first burns after 15 sec with a stedy slow flam. Then suddenly "poof" you get the result in the pic, without the porsche of course.
This is turning into a practical disscution. I'm imagining Vulture saing CLOSED AND MOVED. :P
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[*] posted on 3-9-2004 at 12:39


Quote:

This is turning into a practical disscution. I'm imagining Vulture saing CLOSED AND MOVED.


It is, so don't push your luck. Currently I'm a sleeping dog in the corner, but don't wake me up by straying too much from the dinner table, ok?

On topic:

As KMnO4/Al/S + water is suicide, I used to use acetone to provide more safe and intimate mixing.

Safe I thought...the stuff heats up to about 50C with acetone! I've abandoned this method(DUH!), yet I still am looking for an explanation why this happens.

[Edited on 3-9-2004 by vulture]




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[*] posted on 3-9-2004 at 13:04


So are you saying, a drop of water works just as well as glycerine?
Now shouldn't that be added to the 'Interesting reactions' thread?




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[*] posted on 3-9-2004 at 14:07


Quote:

It burns very slowly in fire and when ignited with glycerine; it first burns after 15 sec with a stedy slow flam


I cannot agree with this - the instant it is ignited it burns with such ferocity it blows whatever I ignite it with out - even my brazing torch!
With glycerine there is a "fizzing" at first but no flame until the flash.

I just added a drop of water to the mixture this minute - absolutely nothing. I then added more and ended up with a puddle of purple water!

Ok, I appreciate this thread is on a knife edge so to move it away can anyone suggest the oxidation pathway of the glycerine?

[Edited on 3-9-2004 by Blaster]
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[*] posted on 4-9-2004 at 05:02


I've now tried several ignition substances for this flash powder.

Ethanol and propan-2-ol do not cause ignition. There is evidence of a reaction but it doesn't get hot enough to ignite.

Ethylene glycol does ignite the mixture but unlike glycerine there is no "fizzing", just a flash after around 10 seconds.

Conc H2SO4 causes instant flash presumably due to the formation of the very unstable permanganic anhydride.

My guess with glycerine is that full oxidation to:
occurs.
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[*] posted on 4-9-2004 at 05:47


It burns as i said before. I don't have a digital cam or a scaner so you'll have to take my word for it. Maybe i screwed it up again :(. It burns very slowly with a flame i suspect the mixture to contain too much KMnO4. Though i did use the volume method you mentioned.
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[*] posted on 4-9-2004 at 06:36


Quote:
Originally posted by Blaster

Conc H2SO4 causes instant flash presumably due to the formation of the very unstable permanganic anhydride.


Hmmm, wouldn't it be a stupid idea to use Sulfur with KMnO4 ? On contact with moisture it could form a small amount of H2SO4, just like that its a very bad idee to add sulfur to a chlorate because ClO2 is formed witch can self ignite at high concentration.




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[*] posted on 4-9-2004 at 09:13
Holy CRAP!!!


I just made a little over a gram of conventional flash powder and ignited about .3 of a gram of it unenclosed. It sounded like a rifle shot!!! It scared the living shit out of me and my mother luckily she is understanding and none of the neighbors called the police. This is the end of the line for energetic materials for me. If this is an LE I can't imagine what an HE is like. O well I guess I have 2 pounds of 3 micron Al that is destined for use in thermites.

(I am sorry if this is off topic but I thought it would be a good warning as to how loud this stuff really is!)
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[*] posted on 4-9-2004 at 10:13


Quote
-------------------------------------------------------------------------------------------------------
Therefore it is impossible to exactly determine the quantities of reactant required. The best that can be done is an approximation.
-------------------------------------------------------------------------------------------------------

IMHO it's more correct to say, "it is impossible to determine the products of combustion" then the reactants required.
I make theatrical pyrotechnics for a living, and I can assure you one thing I make sure of is the exact quantities and quality of my reactants!

Quote
-------------------------------------------------------------------------------------------------------
Mg does make a good flash powder its true. However, I have never come across Mg powder that is as fine as the Al powder commercially available (perhaps its too reactive to be stored and sold when extremely fine) and consequently the burn speed cannot match the Al variant.
-------------------------------------------------------------------------------------------------------

1-11 micron spheriodal magnesium is used quite regularly in pyrotechnics. I get it directly from the manufacturer but I think Skylighter and Firefox sell it. It is amazingly powerful in combination with strontium, barium or sodium nitrate. Mixtures of sodium nitrate and 1-11 mag in quantities of more than about 5 grams will progress to near detonation velocities if ignited unconfined.
I wouldn't even think about combining it with more powerful oxidizers such as perchlorates or chlorates.
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[*] posted on 4-9-2004 at 17:44


I dont think it would be wise to mix nitrates with Mg. Unless you coat the Mg in linseed oil. The nitrates and Mg react and may cause ignition.

Sorry if this is too far from the table vulture, I dont like to wake dogs:)




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[*] posted on 5-9-2004 at 08:08
Flash


Rift valley, by conventional, do you mean 3 micron Al with KClO4 ?



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