mg/al reaction

[memo]

really fine mg/al has been reacting and makeing the stars puffy to the point they will fall apart. will linseed oil treatment stop the reaction

 

memo

[OldMarine]

I use Potassium Dichromate solution to wet all star comps having Magnalium or Magnesium. Seems to do the trick. I tried Boric Acid thinking it might be the Al causing the trouble but it didn't help so I tried the Pot Dich.

[chuckufarley]

OM, do you treat your mg/Al with dichromate prior to wetting with a dichromate solution? Or do you store Mg/Al raw?

[OldMarine]

I used to pre-treat it but several folk who know way more than I said they'd always just wetted the comp with the solution when using MgAl. I DO coat all magnesium as soon as I receive it though I haven't bought any in the past year and probably won't in the foreseeable future. Extra headache outweighs the extra work value . Same with chlorates.

In the same vein, I wet all flake AL comps with a boric acid solution as a rule. It's easy insurance and a $1 bottle from the dollar store will last years.

Edited July 19, 2017 by OldMarine

[chuckufarley]

Thanks, I haven't treated my "raw" Mg/Al yet, I like the idea of treating as a solution to wet the composition, and was curious of the results

[OldMarine]

I only use enough water (+/-6%) to pump my stars since I don't have a roller yet but I think the idea works across the board with only a few exceptions that I can't remember since I decided to forget those comps! Edited July 19, 2017 by OldMarine

[Carbon796]

Memo, what types of formula are giving you theses types of issues ? Also how fine is your Mg/Al thats adding to this ?

[memo]

i was making some 1 inch crosetts out of C6 and added 10% mag/al and also some 1/2 inch stars . the mag/all was -100 mesh I have read that linseed oil will also work. some people sat no others yes.

 

 

memo

Edited July 19, 2017 by memo

[Mumbles]

For magnesium, linseed oil is effective against everything but ammonium perchlorate according to Shimizu. I would expect it to have similar protective properties on MgAl.

 

Generally I don't have a problem with MgAl in stars unless I am trying to force dry them at high heat. This is worse in compositions containing things like sodium oxalate and sodium bicarbonate.

[kleberrios]

Magnalium (Ml) heating occurs due to the oxidation of the particles, releasing ammonia or hydrogen sulphide (egg odor) when it comes into contact with water, acids or alkaline agents, which may be present in potassium nitrate, barium nitrate, Strontium Carbonate, sodium oxalate, potassium chlorate, potassium perchlorate, zircon, PVC (chlorine), etc. If reactions in the manufacture of such salts are not well balanced, such salts may contain acidic or alkaline traces, which will react with Ml causing heat and characteristic odor.

In addition, solvents such as acetone, 99% alcohol and others, have affinity for water, i.e., over time, absorb water from the environment, become aqueous and may react with the metal particles of the generating heat M1, We note this When Smell of these solvents is not so more active when newly purchased, in that case, they should be discarded. Some salts are also hygroscopic (absorb water from the environment) a little more, others less. An example is strontium nitrate (which is practically no longer used in civil pyrotechnics), sodium nitrate, copper nitrate, previously used in blue (contains acid traces), sodium bicarbonate in yellow light (non-hygroscopic), etc.

The addition of 5% very fine potassium dichromate in the mass helps neutralize these unwanted heat reactions, but one must try to know what is causing this reaction if it is due to the presence of moisture, acidity or alkalis in some chemical. Contaminants in the manufacture of ML as water or salts, cause reaction with heat release and characteristic smell, even in your cabinet.

Many use a mixture of distilled water (without added chlorine) of alcohol and dextrin to dragee, important would be to dissolve 5% of Potassium Bichromate to avoid exothermic reactions (release of heat) in the ballast drageia.

Attention should be paid to the use of water with water because there may be alkalinity and traces of salts that may react with ML,

When warming the dragee occurs, do not unplug the drawer, keep it spinning, place the ballads and spread them finely in a pan, in the shade, until cool.

If heated by manipulating mass of color, spread it on the table, avoid mounds and wait for the end of heat production (exothermic oxidation). Normally, after the mass has heated up, this fact does not repeat itself with the same mass, because the metal particles of the ML create a layer of aluminum oxide, which protects it from subsequent heating.

Always check that the stars are completely dry before putting them in the pyrotechnic devices, especially in the plastic plugs (since there is no transpiration) of the rockets of the rods and in the plastic pumps or any artifact that does not occur. There had already been an accident here in Brazil where all the rockets created gases, they steamed and then began to whistle, when they passed the plastic cachopa leaking the gases, until everything was through the air, all because of the still wet stars .

The use of boric acid as a neutralizer is not indicated for Mg and Ml, as it will react with them. Boric acid is only suitable for compositions containing Al powder, for example waterfalls

Edited July 25, 2017 by kleberrios

[OldMarine]

I use strontium nitrate regularly but make certain it is pre-dried and the resulting comp or stars are thoroughly dry as well.

[bpman]

I've not had a lick of difficulty drying strontium nitrate compositions. Also I have not needed to dry strontium nitrate before use.

I had the opportunity to purchase high purity strontium nitrate several years ago and landed a lifetime supply. This combined with my geographic location, (mountains), abates hygroscopy issues.

[NeighborJ]

Memo, does the c6 comp give off a H2S odor? I've recently had a reaction on a different comp which I traced back to my charcoal having a high PH. The stars crumbled just like you described and had no H2S odor.