Potassium nitrate white flares

[val77]

Hello there ! It's been a while to say the least !

 

I don't know if someone here remember when i asked what kind of composition would produce the brightest light for a flare, but i managed to get some MgAl and here is the result : https://youtu.be/SmDkDf9Fkfs

 

The ratio is 50% Potassium nitrate (food grade) and 50% MgAl with an extra bit of sulfur (5%) to lower the point of ignition.

 

However, it looks like the comp burned very fast, as you can see the tube went wild and some thrust seems to be produced. The light produced is satisfying though.

 

The tube used is a 19mm diameter and 40mm in lenght. The composition had a total weight of 11 gramms.

 

The priming was composed of 90% potassium nitrate and sugar (65/35) mixed with 10% of MgAl powder. It performed very poorly as a primer, next time it will be black powder.

 

I suspect that this is due to the magnalium being fine (150 microns or 100 mesh), maybe the use of a coarse one will solve the problem ? The potassium nitrate is grinded with a coffee grinder. It's fine too (but i can feel a slight grit when pinching it between my fingers) so it can also be the cause of that fast burning.

 

 

[insutama]

sounds like you made flash powder

[val77]

It may sound like it but the magnalium is still to coarse to do flash powder (and it is not my intention at all)

[greenlight]

Reminds me of when I tried the flash powder formula using potassium nitrate, sulfur and aluminium. I had spherical Al so it was quite disappointing as a report comp but made an excellent flare (illuminating most of a football pitch) when pressed into tubes. Edited January 16, 2018 by greenlight

[val77]

Another test today, with this time coarser potassium nitrate and without sulfur, with this time 10 gramms of composition handpressed into the tube. Burn time of 10 seconds wich means that 1 gramm of composition is burned each second, not bad: https://www.youtube.com/watch?v=1KX78r9H4U0

[MrB]

sounds like you made flash powder

I guess you are right. Pressing flash-powder probably would make a fair silver flare.

 

 

Not entirely sure i would want to hand press / ram these things. It's probably fine to hand press, but i'd be skittish anyway.

Edited January 16, 2018 by MrB

[val77]

It is recommended to press those compositions when damp (mineral or linseed oil), never dry. That powder can be toxic and spead everywhere

[val77]

Another test today, with 24 gramms to see how long it would last:

As expected, it lasted a little bit more than 20 seconds, wich is what i was looking for.

The primer, wich was the same as the other tests, worked correctly this time. What i did was forming cavities in the flare composition to expose it to the primer's flamme longer than the top filling layout.

 

Here is a scribble i did to show you the cavitie principle: http://www.zupimages.net/viewer.php?id=18/03/uvmx.bmp

Edited January 17, 2018 by val77

[insutama]

What size tubes are you using?

[Ubehage]

sounds like you made flash powder

In my experience, even the "flashy" 50:20:30-ratio of KNO3, S and MgAl is useful for a really nice flare.

Just make sure not to confine it, and it burns relatively slow. But VERY hot and with lots of light.

 

Edit:

I have done this with #70, #150 and #200.

Edited January 24, 2018 by Ubehage

[kleberrios]

 

Twinkling white star #1

51

Barium nitrate

19

Sulfur

18

Magnalium (100 mesh)

7

Potassium nitrate

2

Dextrin

[Mumbles]

That looks like a strobe, not a flare.

[Seymour]

I suggest adding more organics. With the right organic fuel you will slow the burn rate, or with others less so. With the right organic fuel you can make it considerably safer to handle and press. It can also increase flame size.

Since you're cool with some decent priming I'm going to ignore ease of ignition and prioritise ease of use and availability of the ingredients.

Wax would be pretty ideal, but you need to melt the wax, remove it from the heat, dissolve it in a solvent, mix that in with your composition then let it dry. Extra steps but this hobby is full of them, and often they are best not to skip.

But if you wanna get really basic you can use cheap cooking oil, or engine oil or whatever oil.

I'd probably want some carbohydrate too just to help it light (though Resinox would work great too). While essentially KNO3 and MgAl will burn great, Wax and Oil certainly don't facilitate ignition easily.

If you have access to Barium nitrate, that's what you wanna be using. Otherwise, KNO3 works fine.

I suggest something like this. If you use Oil, you can carefully screen the powders then add the oil. In my opinion it can help to add all the oil to a portion of the mix, perhaps 1/4or 1/3rd, mix that in thoroughly then add the remaining dry powder and keep mixing until homogenous.

50 MgAl coarse
40 KNO3 (Or better yet, Barium nitrate)
6 Dextrin, Sugar, (Flour, sawdust, whatever)
4 Wax, Oil (whatever, butter, vaseline)

This mix will press nicely in to tubes. Depending on the size, decent hand pressure may be plenty.

To light it I'd use a primer utilising MgAl for heat and Charcoal for ease of ignition. I'm assuming we're still only talking about KNO3 as an oxidiser.

Maybe

KNO3 65
MgAl 15
Charcoal 10
Sulfur 5
Dextrin 5

I expect that would reliably light from a commercial match or cisco if attached correctly, and should ignite the flare mix easily.