Too Dry?

[roy reali]

All the literature states that powder needs to be stored in a cool and dry place. Is it possbile to have it too dry?

I live in a high desert environment. Our humidty usually hovers in the low single digits. Our lawns are never damp in the morning. After a shower, you are dry before you even grab a towel. Our dogs don't even have fleas, I was told it was too dry for them to survive.

Can such dryness hurt or affect smokeless powder?

[wncchester]

Roy, I'm no "expert" but I doubt your low humidity atmosphere is harmful to power.

It seems the local humidity only indicates the amount of water vapor in air and only has a direct impact on water. We don't want that in our powder anyway. Any other volatiles in powder should stay there for a long time if we keep the lids tight.

[Unclenick]

It probably speeds up the rate at which solvent migrates out of the powder (what you smell when open a powder container). The less water is dissolved in the air, the more capacity it has to take on something else. It will dry moisture content out of the powder, increasing its energy content per unit weight, though it doesn't affect volumetric measuring, AFAIK. This is one reason benchrest shooters rely on volumetric powder dispensing rather than charge weighing. Both permeation processes will take a long time if the powder is in a sealed plastic bottle, as the permeation rate for the plastic will be slow.

I don't entirely understand the effects of moisture on smokeless powder. You are warned that too much humidity is bad, yet Alliant keeps a sample of the first lot of Unique under distilled water to preserve it, and they dry out samples periodically to check for deterioration by testing. In about a century none has been detected. So, clearly, the water by itself is not the issue.

[maggys drawers]

Roy- I live in about the same climate. I've had some powder on hand for over 5 years, and I can't tell of any change in performance. I've got a buddy that has had some powder for at least twice that long- same thing.

I don't think it's a problem.

[oneounceload]

I used to live in the Reno area - the exact environment you're talking about - I kept all my stuff in the garage - over 22 years of reloading components, ammo, etc - all went bang when they needed to with no issues.

[LDBennett]

roy reali:

I don't know what High Desert you live in but I live in Hesperia CA (the California High Desert!). I moved up here 13 years ago from Orange County (CA) perhaps 6 miles from the ocean. I brought powder with me and some of it is still on my shelf. There is nothing wrong with it. Storage in our dry environment seems not to effect the powder in any way I can detect.

LDBennett

[brickeyee]

"It probably speeds up the rate at which solvent migrates out of the powder (what you smell when open a powder container). The less water is dissolved in the air, the more capacity it has to take on something else. "

Partial pressures do not work that way.

The amount of one compound dissolved in the air has no real effect on other compounds.

[GP100man]

What time we have containers open plays little on the longevity of powder , it`s temp swings , the more stable the temps gives less chance of the moisture which is in the powder itself to migrate & condense.

I have a cash of H-110 I bought yrs. ago & "found" I called Hodgdon & it was made in `88 & it still gives the same velocitys accordin to my notes .

[Unclenick]

"Partial pressures do not work that way.

The amount of one compound dissolved in the air has no real effect on other compounds."

For sure they don't work that way for partial pressure of gases that are all below their vapor pressures, but in atmosphere above their vapor pressure I think it can be otherwise. At least, that's what I recall from studying vapor liquid equilibrium sometime back in the paleolithic era.

On reconsideration, though, I also think it may only apply to compounds that are miscible in their liquid states or else in tiny spontaneous isotherms that are below their collective dew points. Though water and ether are both above their vapor pressures in one atmosphere at basement temperature, the liquids don't mix any better than oil and water, so none of that may apply to them.

It also occurred to me that such an effect would be pretty small and was probably therefore a moot point, anyway. A better reason for advocating powder be stored away from moisture, even though it can be stored under water, is likely to be that humidity increases the permeability of the plastic containers we keep it in. That increase can be an order of magnitude in some plastics, and the increase is to oxygen and other gases in addition to the water vapor that brought it about. This idea suggests a dead dry place is the best for powder longevity.

It would be interesting to know what longitudinal experiments have been done with powder storage beside Alliant's sample of Unique? I've heard (but not actually seen the spec) that the military puts a 20 year limit on stored powder age, due, I think, to some unfortunate problems they had with powders stored between the World Wars. Wasn't it that intact nitrocellulose recovered from deteriorated powder could be used in making fresh spherical propellant part of what made the spherical propellant process attractive? That doesn't mean the powder's necessarily gone bad in that time, of course, but does mean they expect deterioration eventually. It seems to me Hatcher had some stuff on this toward the end of his Notebook, but I'd have to refresh my memory on it to be sure.

[brickeyee]

While smokeless powder is not hygroscopic, it will absorb moisture and come to equilibrium with the water vapor it is exposed to.

This WILL alter the density and weight of the powder, throwing even weighed loads off.

Powder is routinely stored under water for long term storage.

Radford Army Ammunition plant still had concrete pools filled with WWII cannon powder in the early 1980s.
It was being reprocessed to extract the nitrocellulose and then used to make rocket engines and newer powder with a higher nitrocellulose concentration.

The old stuff was only in the 50-60-70% range.

[Nnobby45]

Can such dryness hurt or affect smokeless powder?

NO.

Now I don't recommend you freeze dry it to prove the point.

[Nomadicone]

I live in the AZ desert and have had a 50 lb keg of powder that is 35 years old. It still chronos right with the new stuff and no signs of pressure. My guess is your 5 year old is stuff is just a kid.

[lwknight]

A certain amount of moisture is calculated in the powders characteristics.
You could go to extremes and let powder dry enough to alter the properties.
As to how much? I couldn't begin to guess.