Powder and Humidity

[er775]

Here in Mo it is 73 degrees out right now and 90 % humidity
What if any effects does high humidity have on powder and primers that are just sitting on the shelf, I`d love to have a safe or some sort of cabinet that I could store them in with a dehumidifier but dont have the cash for anything like that. I could just close up the house and crank on the A/C but my wallet isnt ready for the utility bill that comes with it

The powder cans are sealed tightly and I store primers in an air tight container as well

[m&p45acp10+1]

It is always at humid here in this part of the state where I live. It has had no ill effects on any of the powder I have used. I keep my primes in the original trays, and boxes on a shelf. They work just fine. I have some magnum large pistol primes that have been on the shelf for a year. I used a few last weekend, and they all went bang.

The humidity, and heat have more of effect on me here in the summer. Sweating in the shade. I have to wear a head band to keep the sweat out of my eyes, and from dripping onto my glasses.

[Daggitt]

I have primers and powder that are over 10 years old. Kept in a dry basement and have had no problems.

[Sport45]

The powder cans are sealed tightly and I store primers in an air tight container as well

Sounds to me like you have nothing to worry about.

[er775]

Yeah its been pretty sticky and thick aired around here the past few days, and being that it stormed all nite and the temps are supossed to get in the mid 80`s today it should be a very sweatfull day

[William T. Watts]

Often times I will have cases that have been primed and powder that I may let sit for several weeks, usually the humidity in the house is at or near 50%, do I have anything to worry about? William

[Slamfire]

Gunpowder is a high energy molecule and it will degrade to become a low energy molecule.

From http://www.dtic.mil/dtic/tr/fulltext/u2/783499.pdf

Nitrocellulose-base propellants are essentially unstable materials
that decompose on aging with the evolution of oxides of nitrogen. The
decomposition is autocatalytic and can lead to failure of the ammunition
or disastrous explosions. Many substances have been used to stabilize
nitrocellulose-base propellants,but by far the most widely used substance
is diphenylamine (DPA).

You can go to www.dtic.mil and search under insensitive munitions, stabilizer, and diphenylamine and find all sorts of information on gunpowders and aging.

Heat is the greatest enemy of gunpowder as it increases the rate of deterioration. The military uses a fume test, they stick gunpowder in a 150 F oven and if it fumes within 30 days it is tested for stabilizer content. If the content of stabilizer is less than 20% the powder is scrapped.

Humidity is bad. Water is a polar molecule and it will interact in a negative way with gunpowder. As water lands and evaporates off gunpowder it hastens the breakdown of the double bonds on the nitrocellulose molecule. It also wicks nitroglycerin to the surface, changing the burn rate of double based powders. The military does not store ammunition in airconditioned buildings, it costs to much. Bunkers are cool, because of all the dirt on top, but they are dank. After decades moisture will become a problem. Combined with heat, that is one reason ammunition dumps go poof all the time.

Incidentally all ionic compounds degrade gunpowder. Rust from those old metal cans hastens the deterioration.

A rule of thumb for gunpowder safe storage is 45 years for single based 20 years for double based. Keeping the stuff cool and dry is better than hot and humid.

Your interior temperatures sound good, just keep the lids on.

[Unclenick]

…And yet, I'm told Alliant keeps a 100 year old sample of the first run of Unique stored under water and periodically dries it out and tests a bit of it and which has proved to be still good long after a double-base powder should have expired. I have often wondered about the cause of the apparent discrepancy between this and the standard recommendation to keep powder in low humidity. A number of possible explanations come to mind. For one, the solubility of acid radicals should cause moisture to make them more active in breaking down other powder molecules, while liquid water may dilute them sufficiently to make them less effective at that. It may be that a moisture differential (outside to in) is mechanically fatiguing the grain surfaces by causing differential swelling that saturation does not, except during initial wetting (not that Unique's flat flakes would really notice). It may be that deterioration depends on small random momentary concentrations of heat at the molecular level to facilitate deterioration that water interferes with.

I can think of others, but I'm just talking off the top of my head and don't actually know.

I have sent an email to Alliant to see if they can offer any enlightenment regarding the apparent contradiction. I'll post the response if it's any good.

In the meanwhile, you can put a desiccant packet in your powder jars or put the whole container into the large plastic zipper seal bag along with a silicone or other desiccant for long-term storage. Intact plastic powder containers take awhile for moisture to permeate in quantity. I did a rough calculation for a high density polyethylene container and it looks like a humidity difference of 0% inside and 100% outside would result in about a thousandth of an ounce every three or four days permeating it. As the humidity inside increases toward the outside level, the rate slows, but even if it didn't, you'd be looking at over a year for a 1% wight gain by a pound of powder going that. So you can see it wouldn't take a lot of desiccant.

[Brian Pfleuger]

I contacted Alliant about that Unique too...

I wanted to make sure the actual facts hadn't been lost in the translations over the years.

The tech told me that they do, indeed, have a very early sample of Unique which is kept literally in water. I was curious if perhaps it was the can/jar that was kept under water, with the powder dry, which had been lost in translation over the years. He said, no, the powder itself is literally in the water, wet. They periodically dry a sample and test it, purely for curiosities sake.

[Unclenick]

Well, that's an important part of the answer. Water all by itself is not the villain. There's always been the issue of the powder gaining weight from taking on water, and that fooling you on how much energy you've got in a charge, so that's part of the argument against exposing powder to moisture, too. Develop a load with wet powder and the same charge weight of dry powder later is too warm.

I'll have to see if they can enlighten us any further?

[er775]

hmm, thats some interesting stuff, just wanted to know if my powder was going to be safe from the high humidity and ended up learning something new,,very cool thanks!

[Slamfire]

And yet, I'm told Alliant keeps a 100 year old sample of the first run of Unique stored under water and periodically dries it out and tests a bit of it and which has proved to be still good long after a double-base powder should have expired. I have often wondered about the cause of the apparent discrepancy between this and the standard recommendation to keep powder in low humidity.

I agree, there is something I don't know.

http://www.castpics.net/subsite2/Gen...-Smokeless.pdf

page 13 there is the water can and powder. Underneath is the statement “do not store today’s powders under water”.

I wish I had a better explanation for this. I am aware that the Navy stored old cannon powder in pools of water, I assume to absorb the nitric acid gas and keep the powder cool. The powder was not to be used, it was being held for recycling. Now how they did that, I don't know.

I asked my friend the insensitive munitions expert, about this, and I got a quick “the lifetime of the powder will be short once it is dry”. I wish I had more detail.

[Brian Pfleuger]

There it is, indeed! Page 13 of the PDF linked in SlamFires post, an actual picture of the powder jar and almost word for word the story I was told by the Alliant tech. How cool is that!

[hooligan1]

So if I'm understanding you fellas correctly Alliant keeps a sample of powder soaking in water, and periodically it pull it up, dry's it out, and lights it up to see what if any effects the submersion had on it???.
ER775, I don't think you have to worry much about good ole Mo. humidity.
But if your loading room floods you will indeed need a de-humidifier!

[Brian Pfleuger]

Originally Posted by hooligan1

So if I'm understanding you fellas correctly Alliant keeps a sample of powder soaking in water, and periodically it pull it up, dry's it out, and lights it up to see what if any effects the submersion had on it???.
ER775, I don't think you have to worry much about good ole Mo. humidity.
But if your loading room floods you will indeed need a de-humidifier!

Correct... except they're not testing the affect of the submersion. They're using the water to PRESERVE the powder.
The PDF does specifically say not to submerge modern powder.

[Unclenick]

I'm going to guess the deterrents that aren't in Unique may not like water. Still no reply from Alliant yet.