20 replies to this topic

[MDH]

Yes, it should work.

Have you tried it? You should also continuously run water through it. Sodium contamination is a problem.

[pyrotechnist]

So I use copper sulphate now instead of carbonate? I assume I then disolve the sodium bicarb with the boric acid in hot water and add a watered down solution of copper sulphate? could the sodium bicarb be replaced with sodium chloride?

[MDH]

No, you need a basic salt. React hot solutions of boric acid and sodium bicarbonate. Once the boric acid has dissolved, add a saturated solution of copper sulfate (meaning, copper sulfate has been added until no more will dissolve). Once the sodium borate solution has cooled down, add the copper sulfate, and a milky-blue precipitate will form.

Pass it through a coffee filter paper, and allow the water to drain. Continue to pass water through it slowly to ensure that there is no sodium contamination.

[pyrotechnist]

I assume this will then be normal copper borate that can be used for colour production etc? I had a similar reaction as you state above using the borax and copper sulphate reaction with a nice light blue participate, I am just waiting to test that salt within a colour comp when I get chance.

[digger]

Just a quick comment. How does Sodium contamination affect this? Is Potassium borate soluble enough for this double decomposition reaction? If so that may be a better route.

Edited by digger, 03 April 2010 - 11:09 PM.

[MDH]

Borax, as I said, is tetraborate - which is great for flash powders as you suggested, and perhaps could be used in strobe formulas like copper phosphate was for some time or in other delayed reactions. But it cannot be used as a serious colorant when compared to other borate varieties.