10 replies to this topic

[nordicwolf]

I got some "Nitrocellulose, Solid" from firefox-fx a year or two ago and have not gotten around to using it yet.  I happened to pull it out today and noticed the plastic pouch it shipped in has expanded like a balloon.  It has not yet burst, so I put it in a large ziploc to contain it should it burst.

 

Why did it expand?

 

Label has this on it:

cellulose nitrate wet w/water; nitrocotton

packed with water - must be dried for use

 

I have kept it stored in a cool, dry location.  label says above 45F and  below 85F.  I sincerely believe those conditions have been met.  I suppose it is possible it got above 85F.  Would that cause the expansion?

 

It is also no longer pure white but has some yellowing at the fringes - pretty sure it is the nitrocotton and not the plastic it is stored in that is yellowing.  I have not opened it yet because I still am not ready to use it.

 

Thanks for any info.

[cmjlab]

NC degrades over time. It degrades faster when dry and in a sealed container (especially a plastic bag), which is easy to tell by the yellow staining and pungent odor of the Nitrogen Dioxide. Excessive / dark yellow stains would be a good sign to get rid of it as it's likely very acidic,and could combust at a much lower temperature than the already low normal ignition temp. Acidic enough could cause spontaneous combustion.

If it's just off white, you may consider soaking it in a baking soda solution and see if it creates carbon dioxide bubbles and/or foams (a sign it's acidic). If it's stained dark yellow, I'd get rid of it immediately, or at least not store it inside a building in case it catches on fire.

BLUF: if it's dry, don't keep it in a sealed bag, it will increase the rate of deterioration. Open it and keep it soaked in water or alcohol, or dispose of it.

I wouldn't want to use parts that have nitrogen dioxide it, and accidentally introduce nitric acid to one of your pyro comps and cause a fire.

Edited by cmjlab, 10 April 2023 - 09:53 PM.

[Mumbles]

I've had a container do that to me too.  When I opened the bag there was an unmistakable odor of nitrogen dioxide.  It smells sort of like bleach/chlorine.  If you've ever gotten whiffs of something similar from automotive or diesel exhaust, that's nitrogen dioxide.  It was starting to turn yellow/orange on the top of the bag a bit.  I neutralized it and washed it, then dissolved it to make lacquer.  

 

The primo industrial NC is wet with alcohol and not water generally now.  I don't know if it stores any better, but it certainly dries faster.  

[nordicwolf]

Where can you get primo industrial NC in the US?

[cmjlab]

Probably have to make it yourself if you know how to safely, or play it safe and buy single/double base smokeless powder. I haven't seen any on pyrochemsource.com in a while.

[Arthur]

NC does decompose, the rate depends on the stabilisers in the original mix. probably these stabilisers depend on the original intended use for the NC. 

The current issue with the OP's NC is that the NO_x from the decomposition catalyses further decomposition. Two possibilities would be to thoroughly wash the existing NC, neutralise it and dry it or to accept that you are ready to use it soon. 

 

It's very easy to nearly make NC. Getting it exactly right and stabilised for storage is much harder. Never assume that the product that you have was freshly made for you! it could have been 20 years old by the time it was put in that bag and put for sale.

Edited by Arthur, 05 May 2023 - 03:39 AM.

[Mumbles]

I'll do some digging for you Nordicwolf. Either I'm misremembering the name of the company, or they've been acquired by someone else. Either way, unless you're looking for drums of the material and have a legitimate business for it, it may be difficult to buy direct.

[Arthur]

Last time I heard of NC for pyro it came in 2 kilo bags packed in 50s in a big plastic drum which was  definitely a ADR/Hazmat item. What no-one specifies in pyro formulations is the degree of nitration, which is very important. Lower nitrations are soluble in different solvents than higher nitrated material, higher nitrated NC burns very quickly, lower nitrations almost don't burn (cellulose paint on cars!). Visco uses low nitration because it needs to let the powder burn at the specified rate.

[cmjlab]

Hercules used to sell NC but I think they were purchased by a different company.

[Mumbles]

I'm drawing a blank on this.  I could have sworn the company name was ATX or something like that, but I can't find anything close.  I'm starting to doubt my recollection of this now.  

[nordicwolf]

No problem, Mumbles.  Thanks for checking!