23 replies to this topic

[sagoraMundy]

OK trying your original comp and I'm wondering if you've left something out of your ingredients list.

You say it's hard to keep lit--not so when I mix it up and bind it with NC lacquer.

Is that your video you link to?

My replication of your exact formula yields a steady burning torch--nothing even approximating a strobe.

That is a kool video--but are you dead certain it's the compound you list at the start of this post?

My results are nothing even remotely like what's shown in that video at pyrobin.

What's the source of that "Optimus' Purple Strobe" formula?

[MDH]

I had a play with that sort of mixture a while back, it produces a huge amount of ash, for a star burnt on the ground really a cinder which if small enough allows CuCl vapour to escape and shine blue. I would guess 3...4mm is the biggest star you could make, which probably explains why there's some very good blues in bombettes/inserts but not in bigger shells

I disagree, not only has blue been in large Maltese shells, brightly competing with other colors for a long time, it's also visible in very hot burning compositions. A purple strobe pot, as well as a blue one, are perfectly possible.

For instance, this video shows a mixture of copper chloride and aluminum burning:

[Creepin_pyro]

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Edited by Creepin_pyro, 20 September 2011 - 04:38 PM.

[sagoraMundy]

Thanx creepinP for responding so thoughtfully to my note.

You may have nailed it with your observation that the Cu shouldn't be too fine; mine's -325 mesh.

(Your video is just so goddam kool I'm determined to get this to work).

Likewise I may have used too much NC lacquer. Mine was a fairly liquid putty consistency; perhaps I need to add only just enough to make the ingredients stick together.

Again, I appreciate your piping up so quickly and with such helpful suggestions.

And MDH's mention of Cu chloride inspires me to experiment with copper salts in standard (Mg and Mg/Al fueled) strobe mixes to see if I can get a good blue . . .

[sagoraMundy]

Says it's a redox reaction and the ingredients listed are 2 parts Al and 3 parts CuCl--but what's the oxygen donor? Will this mixture burn without an (additional) oxygen donor?

For instance, this video shows a mixture of copper chloride and aluminum burning:

[pyrotrev]

I disagree, not only has blue been in large Maltese shells, brightly competing with other colors for a long time, it's also visible in very hot burning compositions. A purple strobe pot, as well as a blue one, are perfectly possible.

That comment was specifically regarding the Chinese blue no.2 and Chinese fireworks in general. I've made 2" comets with a very good blue colour even though they have quite a considerable tail - not too difficult if you use AP as the oxidiser.

[pyrotrev]

Says it's a redox reaction and the ingredients listed are 2 parts Al and 3 parts CuCl--but what's the oxygen donor? Will this mixture burn without an (additional) oxygen donor?

Chemists refer to any reaction where something has it's oxidation number (state) changed as a redox reaction whether or not it's oxygen that's doing it. In the reaction discussed here, the aluminium is being oxidised and the copper chloride reduced. Any oxygen around would likely start to spoil the colour as aluminium oxide gives a pretty strong continuous white spectrum (hence why it makes good flash). One of the strongest oxidisers known is xenon difluoride - no oxygen there!

Edited by pyrotrev, 17 August 2011 - 12:27 PM.

[sagoraMundy]

No argument about your definition of redox--but the above mentioned Cu/Al mixture will not burn by itself. It needs more oxygen than just atmospheric, hence my query as to the exact composition of the mixture demo'd in the vid.

(Just tried it with a little AP and it burned gloriously blue).

And waxing a bit OT, anybody got a clue as to why email notifications of responses to subscribed threads is not working anymore?

Thanks in a trance,
s

[sagoraMundy]

A purple strobe pot, as well as a blue one, are perfectly possible.

Hmm. Gotta invoke the ole cliche here, "talk is cheap." Been working on a blue strobe pot for months and so far nada. Custom blue strobe pots have been recorded at special events but I've yet to find a commercially available blue strobe pot.

Simply sub'ing a Cu salt for another metal salt (like strontium or barium) does not work, prob'ly due to the H20 that's latent in most Cu salts.

Share your formula with us for a blue strobe that works, please.