7 replies to this topic

[Green_as_my_powder]

Fellow pyros,

My son's favorite color is yellow, and I'm hoping to make some yellow stuff (lances, stars...). Many of the formulas require sodium oxylate (sp?) which I don't have. One formula stated I could use sodium bicarbonate instead. Is this universally true, or does this sound like a special case? I can post more details if needed.

Thanks for any advice.

[spanner]

In some cases (many cases?) you can sub sodium bicarb for sodium oxalate. I don’t think either of them are much of a fuel, the bicarb may be more of a flame retardant, however. But this is just a hunch on my part.

Barium nitrate green comps, with a small addition of cryolite or even sodium benzoate will turn it from green to light, lemony yellow. With such a mix, a bit of barium carbonate also serves well as the “antacid”. This is from some old notes, I do not know who to credit it to.

EDIT- The addition of sodium bicarb to a barium nitrate-based green might do the same thing as cryolite, above- sodium is a strong emitter. Some testing would be needed...

Edited by spanner, 22 January 2009 - 01:52 PM.

[phildunford]

You certainly could not rely on a 1 to 1 substitution here, it may work in some cases. Sodium oxylate is somewhat hygroscopic anyway.

Spanner mentions cryolite and this is good for yellows, as it's not hygroscopic, cheap and easy to get from ceramic (pottery) suppliers.

[Creepin_pyro]

The Bicarbonate will act as a delay agent in glitters, not sure how it would affect a colour comp...

As spanner mentioned, Sodium is a strong emitter. You can even get away with using table salt to make a passable yellow in some comps...

It might be worth mentioning that a really good lemon yellow can be quite hard to achieve. Traffic light amber is easy. What kind of yellow are you looking for?

[MDH]

Sodium Bicarbonate will work with perchlorates and chlorates. I am not sure about nitrates. I remember, as ever vaguely, that there is a yellow composition made simply from sodium chloride and black powder ball milled together.

[Arthur Brown]

Sodium salts tend to be hygroscopic and the comps made with them can become damp and unusable, Sodium oxalate is one of the less hygroscopic salts hence it's use. Realistically most sodium salts will work in various amounts and in varying success and lifetime stability.

[Green_as_my_powder]

Thanks for all the info! My first goal was a yellow lance:
Barium nitrate 12.5
Potassium perchlorate 50
Sodium oxalate 25
Shellac 12.5

--from A. Hardt "Pyrotechnics"

come to think of it, I don't have shellac as a powder, just as a solution (in acetone, I think). Anyhow, could I substitue sodium bicarb or cryolite, or do I just need to wait til I can get some sodium oxalate?

Perfect for me would be any formulas for yellow stars or Gerbs without sodium oxalate, or chlorates (I'm still afraid of chlorates). Ammonium perchlorate is also a challenge for me because of the priming issue.

[pyrotrev]

Thanks for all the info! My first goal was a yellow lance:
Barium nitrate 12.5
Potassium perchlorate 50
Sodium oxalate 25
Shellac 12.5

--from A. Hardt "Pyrotechnics"

come to think of it, I don't have shellac as a powder, just as a solution (in acetone, I think). Anyhow, could I substitue sodium bicarb or cryolite, or do I just need to wait til I can get some sodium oxalate?

Perfect for me would be any formulas for yellow stars or Gerbs without sodium oxalate, or chlorates (I'm still afraid of chlorates). Ammonium perchlorate is also a challenge for me because of the priming issue.

Bicarb would work OK in that, but I think you'd need rather less off it, otherwise it'll retard the burning too much. The main no-no with bicarb would be mixes with aluminium in them (especially uncoated) as it's potentially a bit alkaline in solution. Lancaster gives a simple yellow lance mix:

KClO4 75
Cryolite 10
Red gum 15

which should be easy. If you don't have red gum, other fuels would likely do OK.

Edited by pyrotrev, 24 January 2009 - 08:43 PM.