MgAl and black aluminium in flash breakcharges

[dangerousamateur]

Hi

 

My favorite composition for breaking small shells is

 

potassium nitrate 50%

dark aluminium 30%

sulphur 20%

 

I like to literally drown the stars with it to have a massive concussion and usually the stars survive it.

 

Running out of dark aluminium now, i still have very much MgAl (-200mesh) in stock.

 

 

Have you ever compared dark aluminium and magnalium flashpowders, how do they compare?

Which one is stronger, which one is more brisant?

[BurritoBandito]

http://www.amateurpyro.com/forums/topic/2129-flash-powder-safety/page__st__40

 

Edit: I forgot to mention it may be a good idea to add a percent or two boric acid to make it a bit more stable.

 

Edit Edit: had to pull my foot from my mouth. I left the link and suggestion for boric acid because I think they are still relevant. Sorry, it's not my intention to misinform (see my signature).

Edited June 16, 2013 by BurritoBandito

[FlaMtnBkr]

Actually, that formula is used quite a bit. Usually it is with bright aluminum as a slow flash booster, but the sulfur isn't going to make it more dangerous just because he is using dark aluminum. Sulfur and potassium nitrate are used together quite a bit.

 

As far as which is stronger, dark Al or MgAl, I would say dark aluminum. I would assume strength and more brisant to mean the same thing? I say this because of my experimenting with different formulas for slow velocity exploding targets. Also, a pro who I very much trust has said dark Al is more brisant than magnesium. I would assume that would still be true with the MgAl alloy. Mag and MgAl may self confine in smaller amounts and be more reactive, but that doesn't mean they are stronger than dark Al.

[dangerousamateur]

I would assume strength and more brisant to mean the same thing?

Im not sure.

 

Magnalium flash is definitely more sensitive, but i doubt it is a deathmix, at least not with nitrates.

 

I'll try it out somnetime and compare. If its to fast i just mix it with green mix BP.

[pyrojig]

@ flamtnbkr :

That was a very good way of putting a description to the two metal powders. It would need a sand crush test, or pendulum test to display power. The finer magnal is most amazing in reactivity , as stated it confines in very small amounts. Much has to do with the density of the powder in relation to the power. It is found that less reactive very fine atomized al is more powerful( in shock wave) than fine flake al do to this reason. A test at a WPA event showed little to no diff in sound of AL v.s Magnal flash areal salutes. Once you reach a certain size it is hard to tell them apart .

[FlaMtnBkr]

I have some 1-11 micron magnesium powder that I got to experiment with and possibly use in crossettes. But I haven't experimented with it yet because it scares me some. It might be useful in very small amounts but I wouldn't want to mix much at one time. I would be a little worried about aluminum that fine, but magnesium seems like it could be really dangerous since it is more reactive. 200 mesh mag is plenty reactive enough.

 

I would try to get some more dark Al. If you do use the MgAl I wouldn't use some that is super fine and I wouldn't mix a lot at one time. Maybe just enough for one shell. At least get familiar with it in small amounts before using it and try to use the binary method when possible. I don't know the best ratio to use with MgAl but with mag it is supposed to be 50:50 with perchlorate.

 

Anyone know what the shelf life would be on super fine magnesium? I know it can develop mag oxide over time and didn't know if the fine stuff might go bad quicker. With more surface area exposed I would imagine it will become less reactive over time compared to stuff with a bigger particle size.

[pyrojig]

 

Anyone know what the shelf life would be on super fine magnesium? I know it can develop mag oxide over time and didn't know if the fine stuff might go bad quicker. With more surface area exposed I would imagine it will become less reactive over time compared to stuff with a bigger particle size.

 

You are correct , larger particle size stores longer. The finer stuff seems to degrade much faster. It is best to keep in a very well sealed container for storage. The shelf life depends on temps, moisture, and air exposure. Im sure your stuff if stored right will last many years before showing signs of degrading. The 1st stage is a darkening of the metal, then to a very light greyish ( where it is useless) .