18 replies to this topic

[wjames]

Hi folks, few questions here.

I don't make flash powder very often, so when i do, i normally steer towards a relitivly safe option - 50/50 Pot. Nitrate/Magnesium..... normal mesh sizes are 200 for the Pot. nitrate, and 250ish for the Mg Powder. So not really that fine. Now, i'd normally mix it using the diaper method, at arms length, with proper PPE.

Not the most powerfull flash i'm sure you'll agree, but its perfect for what i use it for, and i don't tend to use anything to complicted...i'm a rocket+smoke kinda bloke....though i love nothing more than an earth shattering crack now and again !

Anyhow, i can't get 250 mesh Mg anymore, but CAN get 600mesh atomised Mg Powder - but i have a few questions i'd like to ask the powers that be.


1 - 600 mesh Mg - will that be "airfloat" ??
2 - how much more "reactive" will it be - in terms of being mixed with Kno3....does having finer Mg increase the chances of any accidental ignition ??
3 - should the ratio be changed, or should i aim for equal mesh sizes. ??
4 - Will it become LESS reactive, QUICKER.....by that i mean will it oxide quicker in air than Mg of a larger particle size ??

[fruitfulsteve]

I'm not sure that using MG with any nitrate is a good idea, or i think it is supposed to be coated before hand at least. I will check and get back to you.
my 600mesh MG is definitely airfloat and more reactive both to oxidation and power/sensitivity.
I use german dark AL 33% and kclo4 67% which seems to work ok.

[MDH]

There is a good chance your magnesium will corrode very fast rendering your composition useless, as well as be somewhat nonreactive. Back when I was interested in the challenge of producing a coloured flash, I successfully made several bright red reports out of strontium carbonate, magnesium and polyvinyl chloride - Recently (four years later) I dug up several of these devices to discover the flash now did little more than smoke with a slightly red flame on the ground.

I would advise you to wait until you have a proper aluminum fuel because of the ease of use and shelf life as well. Someone on this forum may be willing to supply you with it.

[pyrotechnist]

I saw somewhere a vid of very fine magnesium powder burning much like flash though a bit slower I am sure it would perform well if confined and this is without an oxidizer.

[CCH Concepts]

There is a good chance your magnesium will corrode very fast rendering your composition useless, as well as be somewhat nonreactive. Back when I was interested in the challenge of producing a coloured flash, I successfully made several bright red reports out of strontium carbonate, magnesium and polyvinyl chloride - Recently (four years later) I dug up several of these devices to discover the flash now did little more than smoke with a slightly red flame on the ground.

I would advise you to wait until you have a proper aluminum fuel because of the ease of use and shelf life as well. Someone on this forum may be willing to supply you with it.

could parlon or pvc be used instead of polyvinyl chloride. im very interested in coloured flash to make for more interesting salutes.

[cooperman435]

PolyV inyl Chloride

[wjames]

Back to my topic.

"600" mesh atomized Mg came today. WOW, is this stuff fine !!!

Anyway, after a few tests on .5g batches of JUST Mg...I.e water, sparks, heat....all looks good.

I then proceeded to obtain some fairly fine Pot. Nitrate - by means of coffee blender, 10g for 2 mins - becomes airfloat.

50/50 mix - 1g total - mixed breifly using diaper method. open tested - VERY fast burning, somewhere between a crack and a pop.....much faster than the old 200 mesh stuff i was using....


I'll report back on my first 5g salute.

And possibly testing of 50/50 flash for impact, heat, moisture, sparks, and shock.

[BigG]

I'll put it this way.

1) You need to coat your magnesium. Might have worked fine for you, but store uncoated magnesium mixed with nitrate for any duration of time and it will be useless.

2) a blender to make nitrate air float? you sure we are talking air float here?

3) I can't see this performing as well as perchlorate based flash - but I guess that will be hard to measure.

[wjames]

I'll put it this way.

1) You need to coat your magnesium. Might have worked fine for you, but store uncoated magnesium mixed with nitrate for any duration of time and it will be useless.

2) a blender to make nitrate air float? you sure we are talking air float here?

3) I can't see this performing as well as perchlorate based flash - but I guess that will be hard to measure.

I only ever make my comps the day they are to be used, so i don't see coating my Mg to be all that important.

Should have written coffee GRINDER.....its got a tiny blade, and does a darn fine job of grinding Pot. Nitrate - it looks and behaves just like icing sugar when its done.

And i don't claim it will perform anywhere near as well as a perchlorate based comp.....BUT, i'd say its less sensitive, and although i may need to use more, it's easier to make, and fairly forgiving !

[Potassium chlorate]

I'm not sure that using MG with any nitrate is a good idea, or i think it is supposed to be coated before hand at least. I will check and get back to you.
my 600mesh MG is definitely airfloat and more reactive both to oxidation and power/sensitivity.
I use german dark AL 33% and kclo4 67% which seems to work ok.

Magnesium and nitrates isn't a problem, except ammonium nitrate, which you are very unlikely to use in flash anyway. It's aluminium and nitrates that might be dangerous. Barium nitrate is the safest (and most powerful, I think) nitrate for flash.

In that case a 65:35 ratio should be used.

[seymour]

I was pretty sure that nitrates and magnesium exhibited a similar reaction to nitrate/Al with Magnesium, but more severely.

[digger]

I was pretty sure that nitrates and magnesium exhibited a similar reaction to nitrate/Al with Magnesium, but more severely.

That is my understanding also.

Edited by digger, 24 October 2009 - 08:48 AM.

[wjames]

That is my umderstanding also.

i must say, ive never seen ANY adverse reaction between the 2, prior to ignition. as ive previously stated, i've tested it at decent lengths.

my findings are, however, somewhat strange.

I used a double walled card tube, double capped....very strong. 5g of 50:50 Pot.Nitrate/600mesh Mg. 5 inch fuse.
The result.....a very quiet"poof" and a big ball of smoke.

Now, normally, i would be using fairly large sized Mg Flake for this.......5g in the same tube was very loud, a sharp "crack" as opposed to a bang.



I wonder why this is. i can only presume the surface area of the Mg is too high, and as such 50% kn03 is to little ???? i would add that 5g of the finer flash powder is approx half the volume of the flash made with mg flake.


any thoughts. i'll try upping the ratio of nitrate, perhaps to 70/30.

[digger]

Ok then here is the list of action of oxidisers on magnesium, these tests are done in the damp state.

Water attacked slightly
Ammonium Perchlorate attacked violently
Potassium Chlorate attacked actively
Potassium Perchlorate attacked violently
Barium Nitrate attacked actively
Strontium Nitrate attacked actively
Potassium Nitrate attacked actively
Sodium Nitrate attacked actively

So if your powders are very dry it will slow the reaction considerably, however if you have a damp nitrate this could lead to a runaway reaction. Also this indicates that the powder will have poor long term storage potential as corrosion will occur, all it will take is a few ppm of moisture to kick the reactions off albeit slowly.

If your new mix seems to be far less powerful the odds are it is down to oxidation of the magnesium either before or after mixing. try mixing some up and leaving it a week or two in a safe place to see if the performance is degraded further.

[wjames]

It DOES react fairly well with water. i'll video a demo for you.

I think you may be right in what you are saying about it reacting over a period of time. it made for good flash 30 seconds after i mixed it, but very poor flash an hour later.

Perhaps i'll carry out some more tests.


Interesting all the same imo