10 replies to this topic

[Gary]

Hi fellow pyro's,

I am thinking of retiring to my workshop this weekend to have a go at synthesising some lithium nitrate from my batch of ceramic-grade lithium carbonate and dilute, aqueous HNO3.
Is lithium comparable to strontium when used in pyrotechnic colour compositions?
Do lithium compounds have any use in mainstream and amateur pyrotechnics?
I have heard of lithium chloride (hydroscopic?) and perchlorate being used (these would presumably form the volatile monoatomic chlorine species when subjected to heat), but when lithium nitrate is used there must be a chlorine donor (such as pvc) present to form the chlorine species, otherwise the colour generated is not very strong.
Are there any good pvc substitutes out there?
Has anyone tried lithium nitrate/magnalium or magnesium in their star compositions?

Thanks for all your advice.

[pyrotrev]

There was an article in JPyro that suggested that it's atomic Lithium that is the best emitter ( a bit like sodium I suppose), not the chloride, so you probably want to make sure you don't have any chlorine donors about and a reducing mix.

[Gary]

I guess that highly electropositive, reducing metals, such as magnesium and aluminium (or a combo. of the two, as in magnalium) would momentarily reduce the Li+ cation to atomic (metallic) Li.

[Andrew]

From experience, Lithium tends to produce a rose/pink colour where as Strontium tends to produce stronger reds. I don't have any experience of Li/Sr Nitrates though. Do report the findings fo your fiddlings, real experimental data is really interesting to read through.

[Potassium chlorate]

If you use lithium carbonate instead of strontium carbonate in a composition where there is only one red colour donor, the colour will be pink.

Though I recently used strontium nitrate together with lithium carbonate and found it to be pretty red, at least burning in a loose pile. Have to make some stars out of it for testing:

Potassium chlorate 50
Strontium nitrate 18
Lithium carbonate 12
Shellac 20

Another possible composition, that I still haven't tested:

Strontium nitrate 39
Lithium carbonate 39
Sulfur 14
Potassium perchlorate 4
Charcoal, airfloat 4

Edited by Pyroswede, 04 October 2010 - 05:33 PM.

[MDH]

If the emitter is atomic lithium then your best bet is to use a highly reactive organic compound with no sulfur, with a majority of the composition being lithium nitrate. The sorbates and benzoates we are always talking about here are a good way to start - Adding a very small amount of dark aluminum or even coated magnesium would raise the temperature. It should be mentioned how hygroscopic LiNO3 is - you will have to store it well (below wax).

Personally to me it seems like if you are going to use lithium for red at all, you should be trying to achieve the magenta like color it provides since strontium simply performs with a stronger red.

Edited by MDH, 04 October 2010 - 06:47 PM.

[vaslop2005]

I have used LiNO3 before, it is an interesting chemical to use, as its products are incredibly light, if not gasious (even the lithium oxide) it tends to burn with a pinky flame when combined with red gum or magnesium, regardless of chlorine donor or not... and makes a lovely pink flash

50 LiNO3
30 Mg
20 nitrocellulose (dissolved in acetone in an attempt to improve storability)

but it is incredibly hygroscopic and the worst I have seen, within 2/3 minutes after drying, it is back into being a mush and useless once more... not trying to hamper experimentation, but its not a pyrotechnical chemical, and never will be, but by all means have a go.

if however your trying to make the best red, have a look at making strontium chlorate (much like barium chlorate, so be carefull) but its unequalled.

[Potassium chlorate]

A pyro friend and I tried to make strontium chlorate this summer but it failed. We still don't know why. We probably dried it too much, so that it turned directly into chloride.

Edited by Pyroswede, 05 October 2010 - 08:02 PM.

[Arthur Brown]

Lithium salts then to be hygroscopic or deliquescent, so they are difficult to use.

http://oxidizing.110...e/chlorate.html See the page on Strontium Chlorate.

[Potassium chlorate]

The carbonate is an exception. Though it's also the salt whose colour is most easily destroyed.

When it comes to sodium, the only completely non-hygroscopic salt is cryolite. That salt also contains flourine, which is a halogen, like chlorine, but since sodium emits its light through atomic sodium and not sodium/halogen ions, it's, ironically, not the best yellow colour donor; simple salts like the nitrate and bicarbonate are superior in my experience.

Except for barium chlorate and maybe strontium chlorate, if you can keep the latter dry, the theoretically best salts for different colours are unusable: sodium chlorate is hygroscopic too and the chlorine won't be of any good, copper chlorate is very hygroscopic and will explode if you manage to dry it and use it in a comp...

Edited by Pyroswede, 06 October 2010 - 07:03 AM.

[vaslop2005]

To make the strontium chlorate, I electrolysed a solution of strontium chloride (carbonate and HCl) and used graphite anodes and titanium cathodes (Ti is key, as the hydroxide formed doesn't 'stick' to it) and then dried, I know this won't be pure strontium chlorate, but it's the best that can really be done..

Edited by vaslop2005, 06 October 2010 - 10:33 PM.