Is it really necessary to coat magnalium stars?

[redbullzuiper]

I make pretty much use of magnalium, and bind them with dextrin using water.

 

However, I read so much about; 'coat magnalium', 'spontaneous combustion', 'dangerous' etc. It made me so freaky, that I cannot leave them out of my sight. Everytime when im on my work, im there with the though: 'Did they survive the day'?

 

Is it really neccesary to coat stars which use magnalium.

 

Lets take a Nitrate based red star comp:

 

Brilliant Red:

53% Strontium Nitrate,

19% Magnalium,

17% Parlon,

11% Red Gum.

+8% Dextrin

Instead of binding them with parlon/aceton I bind them with water. Because I roll my stars. And I dont like the parlon/aceton, because it makes a sticky mess.

How big is the chance they will ignite while drying? Ive not had any problems yet with any of my stars, which uses Mg/Ai.

Why dont you just coat them? you might ask.

Well, first of all. I am not going to use Potassium Dichromate, because of its toxicity and carcinogenicity. I can't work outside and dont have an incredible good ventilated area to work in. It ventilated enough to work with other chems, but I dont want to riks anything with toxic chems like potassium dichromate.

I do however have Linsead oil. But have not really an idea how I can coat magnlium with them. Ive read alot about it, but what ive understood so far is that its hard to do and makes an mess. But I will try it out when I get my new batch of Mg/Ai.

So the bottom question is. How scared do I have to be for the Mg/Ai Nitrate reaction?

[greenlight]

I havent had any trouble from binding magnalium stars with water at all.

 

It is Magnesium metal that is supposed to be coated because of reactions with water and acids that can be formed. Magnalium is quite stable compared to it I am sure.

 

Magnalium is much much safer to use in a composition containing a nitrate salt that needs to be wetted at some point than aluminium.

Nitrate salts, aluminium and water all in a composition is bad news and can lead to self ignition during drying definitely.

 

One of my green formulas is Barium nitrate, parlon and magnalium bound with dextrin and I havent had an issue yet after making them and storing seperately for the first 5 batches.

 

In my opinion, when using a nitrate salt as the oxidizer, magnalium is quite safe even when binding with dextrin.

 

I could be wrong though so am interested to see what others say.

Edited October 12, 2017 by greenlight

[redbullzuiper]

Nitrate salts, aluminium and water all in a composition is bad news and can lead to self ignition during drying definitely.

 

This can be prevented by adding Boric Acid though.

 

Thanks for your input in the subject.

Edited October 12, 2017 by redbullzuiper

[greenlight]

I am fairly sure boric acid only works with aluminium and attacks magnesium and magnalium.

[redbullzuiper]

I am fairly sure boric acid only works with aluminium and attacks magnesium and magnalium.

 

Thats correct. NEVER mix Boric Acid with Magnesium or Magnalium.

 

But mixtures containing Nitrates/Ai should be neutralized using Boric acid.

 

The reaction also does depend on the type of Ai you use. If you use big flake Ai, like Ai bright. It will react quicker then when using small flakes like German dark.

If using Spherical or Atomized the reaction will go slower. This due the flake has an bigger surface area.

Edited October 12, 2017 by redbullzuiper

[NeighborJ]

There are certain formulas which DO spec the use of boric acid with MgAl. Yes it is necessary for some comps but as a rule of thumb acids do attack MgAl as well as strong bases.

[Mumbles]

I've always wondered how intentional the boric acid was in some of those formulas, or if it was just an oversight or perhaps a holdover from flake Al based formulas. I no longer use them together, but before I knew better I never had a ton of trouble with MgAl and boric acid at room temperature. I did however have some issues with glitters being affected if they were force dried with heat. That could be just general glitter issues with heat too.

 

That said, I don't usually have any issues with MgAl and nitrates when using straight water. Barium and strontium also tend to be less prone to issues in general than potassium nitrate. If I encountered a problem with potassium nitrate and MgAl I'd use dichromate.

 

Dichromate coating and/or solution are not effective with barium or strontium nitrate anyway, as it has been noted to strip the coating by forming the respective barium or strontium chromate.

[redbullzuiper]

Thanks for the reply's.

So the conclusion is: "It is not necessarily needed to coat your magnalium".

Im pretty happy with that because, as said earlier, I dont want to mess with carcinogenicity chemicals.

Some other point we should consider regarding this topic, is perhaps: 'What is the size of the magnalium your using?'.

If you use <325 mesh magnalium, its more prone to this reaction then when using, lets say 200 mesh?

Or is this incorrect?

Currently I use 325 mesh magnalium for my magnalium stars. But if above is correct I will switch to 200 mesh, and keep it uncoated. Another thing is, I dont store any of my Items longer then a year.

Even then the question will still be: 'How long will it be atleast storeable without trouble?'.

What I also have read on some other topics, where people actualy tested the reaction was: 'In small amounts this reaction is to small to cause it to spontaneous ignite'. In one star there is only like 3 grams of the formula in question. So this means that it is not enough to, when the reaction happens, ignite the star?

Im sorry for all the questions, but better safe then sorry

[kaotch]

If you want to play it save just coat your magnalium with PARLON.

[redbullzuiper]

Well, you can't coat them with parlon. The only benefit with using parlon as bind, is that it is protected against moisture.

 

But there is no such thing as; 'parlon coated magnalium'

Edited October 13, 2017 by redbullzuiper

[Mumbles]

Of course there is. Parlon is a polymer that can be coated onto things. Anything is possible. This has been explicitly done for Mg, but the properties would work for MgAl too.

 

https://www.amateurpyro.com/forums/topic/3835-coating-mg-with-parlon/

[redbullzuiper]

In that case, im sorry. You are right. Didn't know that. Never have seen that topic. Thanks for sharing!

[kaotch]

Well , now you know and some further advice for dissolving the parlon use Naphta or Acetone and make sure you do it OUTSIDE.

Furthermore I advise you to use the search function first before giving your comments!!!!

[MrB]

Well , now you know and some further advice for dissolving the parlon use Naphta or Acetone and make sure you do it OUTSIDE.

 

Outside... Or, in a closed container, and use distillation to recover the solvent. As always, flammable solvents should be treated with care in this process, if "shit happens" you might blow something up, another way then the regular pyro route.

[PeteyPyro]

Sounds a bit difficult and costly to practically condense, recover, and dry the acetone. (molecular sieves?)

[MrB]

If it's reasonably pure to start with, and only used as a solvent for pyro, then there should be little water added from each batch, and no real reason to dry it.

I've been recovering methanol from biodiesel conversions, which is a much smaller part of the total volume then the acetone would be here, with rather crude means, i don't doubt it would be manageable.

Given the price of acetone around here, i'm not sure it would be worth it, but it would avoid getting flagged for meth production...

[Sulphurstan]

"Even then the question will still be: 'How long will it be at least storeable without trouble"

 

For what i m concerned i m storing some mgal stars for nearly 2 years now, without issues.( veline)

In the plastic container, i ALWAYS add a small batch of calcium chloride in a separate small container full of holes, to keep the stars as dry as possible.

[redbullzuiper]

The Mg/Ai stars I currently have are inside an dry environment. I store them inside a airtight ziplock bag.

Oh, I did found an composition where there Boric Acid is added to a composition where Magnesium is the fuel.

Below compositions are Go getters.

 

Also here it is confirmed once again you can coat Mg with parlon

The melted Parlon in the mixtures will also coat the Magnesium Powder and prevent it from degrading. The Parlon here not only binds the mixture together, but it boosts the color of the flame by providing Chlorine to the burning mixture.[/size]

Im sorry again, ive never noticed anything regarding parlon as coating.

Im wondering how 'safe' these compositions are because of the added Boric Acid. And what does the Boric Acid do in this composition anyway?

Edited October 17, 2017 by redbullzuiper

[greenlight]

I don't know what the boric acid is added for in those compositions. Usually it is to neutralize any amide formation in Al and nitrate compositions to prevent spontaneous initiation of the mix from the heat generated as a byproduct of the side reaction.

 

From what I know, boric acid should not be used with magnesium as it attacks the metal.

Where did you find those formulas?

[kaotch]

Boric Acid should be used with compositions containing Al. only for reasons already posted and it attacks magnalium as well!!!

I wonder , where did you find those formulae?

When using magnalium in a compostion and you don't want to worry about safety too much , use PVB or a combination of PVB and Phenolic Resin as a binder, rolls , cuts and pumps like a charm. You have to recalculate the composition in order to maintain the right oxygen balance.

[NeighborJ]

Green light, yes I agree that boric acid should not be used with magnesium BUT this is MgAl which is a lot less reactive to ph imbalances. I found a brand new formula yesterday which was added to the fireworking.com database which uses boric acid and MgAl. Unfortunately there seems to be some sort of a problem accessing the site today, I will post the example as soon as this problem is resolved.

 

I have personally had an example of needing to add boric acid to a MgAl comp to prevent a reaction. The comp I used it in was pyrotex' s sodium nitrate glitter. I had a reaction which caused the stars to crumble into dust, I traced the issue to the charcoal which I picked (oak) which turned out to have an extremely high ph. I added boric acid to the next batch and the issue went away.

 

This may not be a typical use of this combo of chems but it may be the reasoning behind its appearance in many comps. Many charcoal tend to become quite basic and the acid is likely added as a preventative measure, (just a theory).

 

Ok an update, I've found the new formula in question. Independence white strobe star: KNO3-52.4, MgAl-20, BaNO3-9.5, sulfur-8.6, Boric acid-4.7, dextrin-4.8

 

This formula does not support my theory of charcoal PH balance due to the lack of charcoal so there must be some other reason for its use.

Edited October 17, 2017 by NeighborJ

[Mumbles]

Just because it's included, doesn't necessarily mean its 1) Necessary or 2) A good formula. I've seen a lot of instances where it's included just out of habit because manufacturing firm X used it in all their glitters and streamers when they were based on aluminum. Why not add it to MgAl glitters too, or strobes, etc. I think the reality that boric acid is incompatible with MgAl is only more recently becoming common knowledge.

 

I've certainly added it to plenty of MgAl glitters in my time without too much of an issue. In my experience, the only time it has really destroyed the effect is if the star is heated. Many reactions accelerate at elevated temperatures.

[greenlight]

NeighborJ, I only stated that boric acid should not be used with magnesium because the formulas he listed contained the two together and I know the Mg would be attacked..

 

I am unsure on the degree of instability when using boric acid and MgAl as I have never used compositions with the two together so I have no real input on that apart from my reading that they shouldn't be mixed.

[redbullzuiper]

I found these formula's on http://creagan.net/fireworks/compositions.html

 

Seems like a very helpfull website for any pyro hobbyist.

[Sulphurstan]

If you have FAST, have a look to table 12. In my point of vie, Prof Shimizu is probably in the top five of 20th century fireworking, he made extensive scientific research about FW. And his table 12 is mentioning the action of h3bo3 on MgAl. Edited October 17, 2017 by Sulphurstan