Boric Acid & AL

[pyroguy1960]

So I'm about to embark on my journey to chase the golden star comp that I like best. All the comps I'm going to use call for boric acid to stop the reaction of AL w/Nitrates/water. The AL I'm using is -20 mesh, dark flake, coated. Eckart #41813/G

 

My questions are as follows:

 

If the flitter AL I intend to use is "coated", do I still need boric acid?

 

If so, isn't it better to dissolve the boric acid in the water I wet the comp with that to coat the AL or should I just add it to the comp as dry powder?

Edited October 17, 2010 by jms04081974

[Ralph]

if your Al is coated than it should have a hard time reacting most of these warnings are for larger batches as 5kg of comp can not dissipate heat like 500g or a flat patty. personally what I do for "risky" comps or just a new comp of that style I haven't made before is just make it away from everything elce in a place were if the comp catches fire there will be no problems but really with these reactions the amount it does react depends on how hot it gets so in a small bath you should have no problems

 

as for the adition of boric acid adding dry powder will give you an exact amount added though dissolving it in a pray bottle and using that to wet the comp is probably easier (its what I do)

[Mumbles]

20 mesh is probably coarse enough not to worry. It never hurts with aluminum though. Watch out, because it attacks MgAl though. I've ruined several batches of glitter before figuring that one out.

 

The only time I think it's absolutely required is with bright flake or finer aluminum in conjunction with a fairly basic salt like sodium bicarbonate or oxalate.

[pyroguy1960]

Thankfully none of the comps I'm testing call for MgAl...so no worries there.

 

I do use a little MgAl w/green mix sometimes for a hot prime....I wonder if I should be putting a small percentage of Potassium Dichromate in that hot prime mix?

[AdmiralDonSnider]

Boric acid is best used in solution; otherwise it isn´t distributed well. As the others have said many comps do not need boric acid at all; I do however use it in the solvent when making Al based glitters without sodium salts (the acid will react with them to form borax).

 

As far as bright Al is concerned, most of the bronze grades are heavily stearine coated anyway and don´t need the acid either.

 

Dichromate can be added to the solvent (about 5%) when MgAl is present in a comp. This is not vital however.

[Mumbles]

I am going to have to take issue with two things you said there. Firstly, boric acid is not strong enough to neutralize the bicarbonate ion, so no or very little borax/borates are formed. Try mixing boric acid with sodium bicarbonate and see if there is a reaction. I've tried, and even overnight there was no mass loss, which would be a sign of neutralization as CO2 escapes. Secondly, even the coating on bright flake is not enough to protect it from a strong nitrate attack. I would only recommend making this composition to my enemies, but I did manage to get the mess kit willow to heat up and give off H2S. It didn't even have any basic salts in it. I've only ever had one other comp heat up on me, but I don't remember which comp, but it had both sodium bicarbonate and bright flake. I've heard some people say that the basic salts just turn the stearic acid to soap and dissolve it away.

 

http://www.skylighter.com/fireworks/how-to-make/willow-fireworks-stars.asp

[Algenco]

I am going to have to take issue with two things you said there. Firstly, boric acid is not strong enough to neutralize the bicarbonate ion, so no or very little borax/borates are formed. Try mixing boric acid with sodium bicarbonate and see if there is a reaction. I've tried, and even overnight there was no mass loss, which would be a sign of neutralization as CO2 escapes. Secondly, even the coating on bright flake is not enough to protect it from a strong nitrate attack. I would only recommend making this composition to my enemies, but I did manage to get the mess kit willow to heat up and give off H2S. It didn't even have any basic salts in it. I've only ever had one other comp heat up on me, but I don't remember which comp, but it had both sodium bicarbonate and bright flake. I've heard some people say that the basic salts just turn the stearic acid to soap and dissolve it away.

 

http://www.skylighte...works-stars.asp

 

 

I can vouch for the strearic converting to soap.

I've made lots of soaps and Strearic acid is used a lot. I have several lbs:)

Edited October 18, 2010 by Algenco

[pyroguy1960]

so what's the consensus here....what do I do?

[Algenco]

I know nothing about chemistry, I would follow the formula to the letter

[Updup]

You guys think I should be using boric acid with small (200g) batches of D1 or Ralphs glitter?

[AdmiralDonSnider]

You guys think I should be using boric acid with small (200g) batches of D1 or Ralphs glitter?

 

No, I don´t think it´s necessary, at least if you´re using atomized grades.

 

 

@Mumbles: It was a pyro factory owner who told me that boric acid shouldn´t be used with sodium compounds. I have never done any chemical analysis to verify his theory. It is Hardt who says that boric acid is not vital when using stearine/grease coated aluminum (see his table on Glitter formulas). Both sources may be wrong indeed.

 

Boric acid supresses metal fuel loss in an otherwise basic environment. There are only few cases where it does have a real safety, not just an aesthetical value. Ofca (technique in fire vol 5) mentions that there are comps "optimized" to heatup, but even then kilo batches are necessary.

[Mumbles]

I have to agree in most cases it's unnecessary. When working with aluminum, it usually doesn't hurt anything, but only with bright flake do I ever really find a need. Even then it's only rarely needed. Just personal experience has shown me that bright flake with basic salts more frequently brings on a reaction. Perhaps my aluminum is not as coated as some other brands.