Powder storage question

Although I agree 100% with slamfire I feel there is a caveat to that . I'd rather have my powder upstairs ( not attic ) where it gets in the 80's some times rather then a basement where humidity can be 95% some times .

Would I be wrong in that line of thinking ?
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If the upstairs room is low humidity and low 80's, that sure sounds like the best overall decision.

I really don't know the tradeoff between heat and humidity. Almost everything I have read is about temperature aging. I do not recall anything on the storing of modern powders in high humidity, whether it ages powder faster than temperature. I do know, for pre WW2 powders, water immersion was bad. Some of the stuff in the gunpowder dissolved into the water and caused cracking in the grain. I don't know if that was fixed later.

I have heard from an insensitive munitions expert that humidity is bad for double based gunpowders. Water in the air, its called humidity!, condenses and evaporates on the gunpowder grain. Water is polar-covalent and the positive end wicks nitroglycerine to the surface. In time the surface of the power grain becomes rich in nitroglycerine, and that will spike the pressure curve on ignition.
 
I have heard from an insensitive munitions expert that humidity is bad for double based gunpowders. Water in the air, its called humidity!, condenses and evaporates on the gunpowder grain. Water is polar-covalent and the positive end wicks nitroglycerine to the surface. In time the surface of the power grain becomes rich in nitroglycerine, and that will spike the pressure curve on ignition.
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I remember unclenick talking about that or something about that . It was and or what I got out of it was . Using and continually opening a jar of powder in a room with high humidity will cause the powder to absorb some moisture causing it to weigh more . Take that one thought further and now you are also closing that air tight lid on the powder that now contains more moisture then intended and locking it in . Now what is that doing to the shelf life of that powder ???

Things that make you go hmmm :)
 
Honestly, I dont think it matters how you store powder (upright vs sitting on it's side). I think it's more important to store it with the cap on tight, the foam seal on under the cap, and away from high heat, direct sun light, and of course flame. I used to store 1 pound cans on their side in a drawer, nowadays I keep it on a closet shelf where it's dark, semi cool, and away from any flame sources. I do transfer powder from 8 pound kegs to 1 pound bottles for use, so that the entire 8 pound isn't opened and closed constantly over a long period of time during use. I think we all use opened bottles of powder long before exposure could cause an issue, and of course an unopened bottle, even in a humid climate will last many years before it's affected. Even then I doubt most of us would even notice.
 
Not a question I ever thought I would see.

Ok, my take is it makes zero difference if you store it right side up, upside down, on its side or 45 degree angle.

Also my take is with Slamfire, cooler is better though warm is probably not an issue (I have powder that was moved around for 25 years in all sorts of storage though mostly cool) and it shoots fine.

I have almost empty powder containers that are ok (though I agree that fuller is better for long term). Less oxygen to attack (accelerate decay) of your chemicals)

and last, if your container is sealed humidity is not a factor, its outside the dry powder (sealed) is inside.

Whatever humidity was when you opened the powder and then sealed it is going to be what you have, nothing exterior will affect it (short of having it at say 120 degrees, putting a lid on it and then cooling it off to 40 degree, remote possible it might suck in moisture but a good seal no.
 
Very interesting and informative. I buy 1 or 2 lbs at a time, store it inside with HVAC probably 90% of the time. I use a wooden crate about the size of a machinist tool box with metal handles on the sides, figure I can carry it out of the house if needed or toss it out a window. I've noticed that the original containers allow a bit of empty space and feature tops that will pop off, no doubt to prevent too much compression in the event of trouble. As the container depleats I usually transfer the powder into something smaller - I know it's a no-no - but always label very carefully, and what I have been using is a type of bottle for vitamins or nutritional supplements with a screw-on top that has a built in flap that would easily pop open. I also have a piece of paper with a few kernels every powder I have ever used under scorch tape so I can do visual comparison. Even the mystery powders from salvaged cartridges are labeled by cartridge and charge. I don't really go to it very often, but I like to know I've got it.
 
I put small desiccant packs in my powder jugs. I then store the jugs with large desiccant bags in a cool, dark area. On a regular basis, I "recharge" the desiccant by heating them in an oven per the manufacturer's directions. That may be overdoing things, but the desiccant is cheap insurance against humidity, considering it's "rechargeable."
 
And chemical reaction between a desiccant and a powder?

Outside the container if you really are soaking wet environment, keep the container full up.

Powder is extremely impervious if you don't mess with it
 
I'm not a chemist, so I suppose there could be a chemical reaction between the desiccant and the powder, but I'm using desiccant packs like you find in new camera packages, pill bottles, etc. They have a covering - which by necessity must be permeable to some degree - but physical contact between desiccant and powder is still minimal, if any. Plus, wouldn't the nature of a desiccant - drawing moisture to itself - tend against a chemical reaction with the powder? Not being a chemist, I can't really say. Maybe the desiccant bags where I store the jugs prevent too much moisture from getting into the jugs in the first place. What I can say is that I've never had any issues in the six years I've done it.
 
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