23 replies to this topic

[Mumbles]

Have any of you guys ever seen a pure elemental boron flame? I sure haven't. The only time I've use it is in e-matches, and there was enough metals in there that you couldn't see it. I had a look through Hardt, and the older Ellern, and found no mention of Boron being used as a colorant in any sort of pyrotechnics commercial or military. The main use seems to be in igniters and gasless delays. The gasless delays were mixed with barium chromate, so you'd think they'd burn green. Alas, no gas no flame.

At the beginning of the chapter (16) on pyrotechnic materials Hardt actually says this: "Some materials, such as boron, are important in military pyrotechnics but are absent in fireworks because they do not produce useful visual
effects, quite apart from their cost."

The one reference I found specifically mentioning using elemental boron as a green colorant came from Wikipedia. If that were not bad enough, it was cited as coming from a Kosanke book, which IMO makes it even less likely to be true.

Edited by Mumbles, 27 January 2010 - 07:54 PM.

[pyrotechnist]

interesting i remember seeing it being sited on some chemical sites though cannot to the life of me remember which ones stating it was used in some pyrotechnic flares and that is only the amorphous boron. Someone posted a message either in this topic or elsewhere on boron stating a book that contained a formula using amorphous boron to produce a brilliant green.

[MDH]

Have any of you guys ever seen a pure elemental boron flame? I sure haven't. The only time I've use it is in e-matches, and there was enough metals in there that you couldn't see it. I had a look through Hardt, and the older Ellern, and found no mention of Boron being used as a colorant in any sort of pyrotechnics commercial or military. The main use seems to be in igniters and gasless delays. The gasless delays were mixed with barium chromate, so you'd think they'd burn green. Alas, no gas no flame.

At the beginning of the chapter (16) on pyrotechnic materials Hardt actually says this: "Some materials, such as boron, are important in military pyrotechnics but are absent in fireworks because they do not produce useful visual
effects, quite apart from their cost."

The one reference I found specifically mentioning using elemental boron as a green colorant came from Wikipedia. If that were not bad enough, it was cited as coming from a Kosanke book, which IMO makes it even less likely to be true.

Mumbles, haven't you heard of potassium nitrate and boron stars? They do exist, though they rely on the pure element. There was a video of them on pyrobin years ago. Recreational pyrotechnics had several discussions about boron and potassium nitrate stars.

I believe the composition was 60:40.

Edited by MDH, 28 January 2010 - 02:50 AM.

[Creepin_pyro]

Managed to track down a small amount of amorphous boron recently.

Mixed up some nitrate 'flash' and it gives a very nice green - deeper colour than my attempts with other green flashes, although I'm yet to try this in a casing/in the air...

I intend to make some stars using it as a secondary fuel (Baechle), not sure about the 60/40 nitrate stars though, in terms of binding etc... any thoughts on this?

[MDH]

I would very much appreciate a video of it, simply to see the burning characteristics of the metal itself. From what you are saying, it sounds incredibly reactive like magnesium.

I'm not sure how the 60:40 ratios are bound, but through searching you can find that 75:25 or 85:15 are also common ratios, but they are used for ignition rather than as stars.

[a_bab]

I read in some old pyro book that boron coumpounds were used in the past for green formulas. Couldn't track down a formula though.

Another interesting fact is that a 5:1 mixture of methanol/conc. sulphuric acid is used as a qualitative analysis for boron (just add some unknown compound to a bit of this reagent and if it burns green then there's boron in the sample).

Creepin_pyro, does it happens that your boron comes from the cheapest (cough polish) supplier in EU and you've got like 50-100 grams?

[pyrotechnist]

Anyone know how to get boron from boric acid or borax?

[Mumbles]

It's not very easy.

Step one: Convert borax to boric acid by adding HCl and cooling to precipitate the boric acid

Step two: Heat strongly under vacuum to decompose into water and B2O3 (which will never go to completion)

Step three: Reduce said B2O3 with magnesium in a thermitic type of reaction or alternatively I bet you could use coke or maybe even hydrogen.

[Creepin_pyro]

I would very much appreciate a video of it, simply to see the burning characteristics of the metal itself. From what you are saying, it sounds incredibly reactive like magnesium.

It's very interesting - doesn't want to take fire from a direct flame but when mixed with the nitrate it behaves similarly to Mg nitrate flash, at least in terms of ease of ignition and burning speed. I'll do a few videos next time I do some tests.

Creepin_pyro, does it happens that your boron comes from the cheapest (cough polish) supplier in EU and you've got like 50-100 grams?

No, this was a sample straight from the manufacturer. I haven't seen it available from the usual pyro suppliers...