14 replies to this topic

[AdmiralDonSnider]

Although oxalates aren´t extremely popular in pyro (except the sodium variety), I´d be interested if and how they could be easily synthesized at home. I´m not really skillfull at chemistry, but know that one starts out with oxalic acid :-).

Strontium oxalate is required in some red formulations, and - along with lithium, calcium etc. oxalates - would probably give a nice pink tone to glitter spritzels (given that low-sodium chems are used). Promising enough...

[digger]

Although oxalates aren´t extremely popular in pyro (except the sodium variety), I´d be interested if and how they could be easily synthesized at home. I´m not really skillfull at chemistry, but know that one starts out with oxalic acid :-).

Strontium oxalate is required in some red formulations, and - along with lithium, calcium etc. oxalates - would probably give a nice pink tone to glitter spritzels (given that low-sodium chems are used). Promising enough...

Simply react oxalic acid with the carbonate of the metal you require. Do the stoichiometry to work out the masses required and add a small excess of the carbonate.

Good luck on the pink glitter, let us know the formula when you perfect it. I have tried a few pink glitters and have not been satisfied with the result yet.

The Lancaster gold glitter is nice with sodium oxalate, one of my favourite glitters.

[MDH]

At this point, if I were you, I would just make a lot of colored microstars with a fast burning composition. The imperfections of the prime will act as a delay agent and will provide you with a perfectly viable colored glitter.

[pyrotrev]

At this point, if I were you, I would just make a lot of colored microstars with a fast burning composition. The imperfections of the prime will act as a delay agent and will provide you with a perfectly viable colored glitter.

Alternatively coloured strobe microstars can be used - very pretty and a bit more delay/hang.

[AdmiralDonSnider]

May be entirely scholastic, but I guess you can´t roll these microstar containing comps. Sounds like a project for a pump.

Could someone probably describe how making e.g. strontium oxalate is done, starting from oxalic acid and SrCO3? I don´t know how to calculate the correct amounts...

Good luck on the pink glitter, let us know the formula when you perfect it. I have tried a few pink glitters and have not been satisfied with the result yet.

Oglesby stresses the necessity of using low-sodium chems, and washed charcoal!

Edited by AdmiralDonSnider, 04 March 2010 - 04:47 PM.

[Creepin_pyro]

Sorry I can't help with the synthesis, but...

Has anyone actually seen pink flashes from pink glitter comps? I've tried a few with useless results...

The Kosanke's apparently did a study with a control group who weren't told the glitter was supposed to be pink - none of whom saw and pink hue. A few of the group that had been told to expect pink did indeed see pink. There's also a depressing list of chems/metals which have been found to NOT work in coloured glitter, including oxalates.

[AdmiralDonSnider]

Ok, I decided to "learn" this myself and found out that:

(COOH)₂ + CaCO₃--> Ca(COO)₂ + CO₂ + H₂O

Theoretically, 90.04 grams of oxalic acid mixed with 100.09 grams of calcium carbonate will give 128.1 grams of calcium oxalate, right?
As oxalic acid is a solid, it has to be dissolved in water, right? Does this make a new equation necessary? Will the reaction produce the monohydrate or plain calcium oxalate? As I said, I´m a bad chemist.

I´m not after the pink glitter mainly; it´s the said rich gold of calcium oxalate glitters that catched my attention. I´ve seen numerous gold glitter cakes showing a stunning gold I´ve not been able to reproduce so far. Not the usual sodium yellow...

[AdmiralDonSnider]

No ideas, anybody? Shall I just dissolve the acid in as much distilled water as is needed?

[digger]

I will put a solution up for you later when I get a minute

[Alexander]

Your maths/chemistry looks fine and will not be affected by doing the reaction in solution but it may not be the best way to do it practically. Calcium oxalate is essentially insoluable like calcium carbonate, reacting a solid to produce another solid in this way can be problematic if the new solid coats the particles of the old one preventing contact with the solution.

A better way can be to arrange for everything to be in solution at the start of the reaction and cause the product to precipitate out. For example, if you dissolve solid oxalic acid in potassium carbonate solution to produce neutral potassium oxalate (K2C2O4) which has a solubility of 33g per 100ml at 16C (according to my CRC) and then add this to a solution of calcium chloride you should make the oxalate free from any carbonate contamination. Means redoing the math I'm afraid.

The product will probably be the hydrate, which may be dehydrated by heating to 200C (again according to CRC, air excluded I would think), is it certain the product used for fireworks is anhydrous?

Obligitory remainder about oxalic acid and its soluable salts being poisonous and the importance of washing hands.

[AdmiralDonSnider]

Thanks Alexander.

I wonder if traces of e.g. strontium carbonate will present a problem in case the oxalate is used in red comps or glitters anyway. In the latter case it will probably add to the delay. It´s not like having sodium traces in...However, good point!

[pyrotechnist]

Any full method yet on making calcium oxalate?

[AdmiralDonSnider]

Any full method yet on making calcium oxalate?

I´d be interested in a tried and true method, too.

[pyrotrev]

I´d be interested in a tried and true method, too.

I've not had reason to do this, but a similar method worked fine for Mg oxalate:
Dissolve 57g (slightly over 0.5 mol to take account of moisture) anhydrous calcium chloride in 100g warm water. Dissolve 63g (0.5 mol) oxalic acid dihydrate in 100g boiling water, and add to the CaCl2 solution with vigorous stirring, it will form a thick precipitate. Allow to cool then filter off the preciptate, reserving the liquid (which will be moderately strong HCl - this can be regenerated into CaCl2 by adding calcium carbonate), wash the precipitate until indicator paper shows it to be free from acid, then dry.

[Mumbles]

The method just posted looks good to me. Most of them seem quite reasonable actually.