11 replies to this topic

[Gazza]

Hi, has anyone ever heard of copper oxalate being used in blue star formulas? The gasses formed when it decomposes have a cooling effect on the flame- ideal for copper blue emission at relatively low temperatures. It is easily made by reacting a solution of copper sulphate with an oxalate (by the way, sodium oxalate is often used in pyrotechnics to produce gold/yellow sparks), or by reacting copper carbonate with a solution of oxalic acid. Copper oxalate is insoluble in water, just like copper carbonate or oxide. If sodium oxalate is used to prepare it, the copper oxalate precipitate must be thoroughly washed with warm deionised water, to remove all traces of sodium.
All oxalates are poisonous by ingestion, but with common-sense and observance of safety rules, risks should be minimised.

[YT2095]

actually the Copper is just as toxic as the Oxalate Anion.

I`v never heard of this being used, BUT, I do have the Copper carbonate and the Oxalic acid (I avoid Sodium ions at all cost for any color work), so I may just make a gram of this and let you know (I got 2 weeks holiday WOOHOO!).
what is the Oxidizer used? any idea?

[Gazza]

I guess the oxidiser would be potassium perchlorate or ammonium perchlorate- either can be used in blue star formulas, since they decompose to form the volatile monoatomic chlorine species. As you probably know, potassium chlorate can not be used, as copper sensitises it. I do not think that potassium nitrate is used in blue formulas, not without a chlorine donor, anyway. Find a typical formula that uses copper carbonate (shimizu, conkling, lancaster, etc) and use the copper oxalate in place of the carbonate.
Try the PFP database, or go to pyrowiki- they are chock full of formulas.

[YT2095]

well, I`m not Technically a "Pyro" I`m a chemist with an Interest in it, so I don`t know Any of these sites you mention (I`m not TOO computer literate either).
but I AM willing to test a Known formula out for you and present an opinion

Edited by YT2095, 16 October 2007 - 05:33 PM.

[Mumbles]

Both formulas should work pretty well. I've never actually made them, I stick to CuO as my main blue colorant. Just replacing 1:1 should be alright, as they are reasonably close in MW. Technically a bit more CuOx should be used, but just for qualitative tests. Should want to be more precise, add about 10% to the copper salt mass proportion. So if the original proportion is 12%, use 13.2%.


Here is the Shimizu formula:

Potassium Perchlorate 60.8
Parlon 13.1
Copper(II) Carbonate 12.3
Red Gum 9
Dextrin 4.8



Conkling:

Potassium Perchlorate 65
Copper(II) Carbonate 14
Parlon 10
Red Gum 6
Dextrin 5

[Creepin_pyro]

Haven't heard of it being used, but this snippet from REC.PYRO suggests there are already some forumlas out there...

donald haarmann
-----
I don't have time to breakout the blues only, I should be down in da' basement
routing through dovetails in four-quarter cedar, for a planter. Therefore I
supply the following:— Number of formula using copper/copper salts in my DB.

..... copper oxalate 3

Might be worth cheking out the Wiz' book.

[YT2095]

ok, I`ve made a few grams of copper oxalate and am just waiting for it to dry out.

now an interesting thing is that it`s already quite Oxygen rich as CuC2O4.
and you know that all Percs are also Oxygen rich xClO4.

so you either will need Very little and hope to make CuO, OR it needs some other reductor!

I think you can all see the problem that I`m facing here in trying this out for you, Copper Oxalate and xPerchlorate isn`t likely to be very interesting.

so if you can throw me a Bone....

[Arthur Brown]

Both the formulae in Mumbles post use red gum and dextrin these will be both organic binder and fuel. Stars are usually over fueled (for the stoichemetry) as they rely on passing rapidly through the air. The only way (short of launching a shell) of testing stars is to fire one from a star-gun. ( A miniature gun the scale of a Verey pistol cartridge) This way one gets an impression of the inflight performance.

[YT2095]

therein lies the problem(s).

for a start I don`t have red gum or Parlon only PVC powder and dextrin (never had a use for the other 2) and secondly I refuse to make Any pyro device unless registered and legal to do so.

So.... that leaves me with a Powder comp in a flash pot

That I AM legal to do.

[lavenatti]

I've seen a few blues using lactose as a fuel. You may try substituting that for the red gum. In a real pinch a little confectioners sugar may work for experimentation.

If you were using a chlorate as an oxidizer I'd say try some shellac. Shellac burns lousy with perchlorates.

[YT2095]

I tend to use Halates for other things rather than conflagration mixtures, Perhalates I think would be better suited to a copper compound I recon.
although stability in an open flashpot with miligram amounts isn`t likely to affect me badly, if someone made a larger amount... well it`s probably best not to go there

[cooperman435]

I cant see how a star gun is illegal? a few tubes welded to a plate isnt illegal or a weapon especially when empty. You would also be directly conforming to the law by "testing" your compositions rather than making something from them therefore constructing.