Are powders hygroscopic?

243winxb

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Compare a new fresh lot of powder with your old lot by volume.

Use the same powder measure setting. Settle powders. Do 10 drops each for an average weight.
I have checked 3 powders so far. The new lots are heavier.

It would seem something evaporates out of the old* powder?? Different powder=Different results?
 
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243winxb

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Pro2A

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May 23, 2009
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Someone asked me today, I'm not sure. We talked about powder being able to wick moisture into plastic containers during long term storage OR if the container lid wasn't tight resulting in the powder absorbing moisture.
Can't say I've experienced either.
Although I have extensive background in packaging container design and materials, I am not familiar with the specific formulations of powder containers. Plastic containers are not impervious to moisture transmission. There is a Moisture Transmission Rating for each plastic formulation. Polyethylene containers (PE).....ala milk jugs....are pretty much like plastic sieves on the MTR scale......kinda like the Gore-Tex of the plastic world....don't leak, but pass water vapor like a sieve. Even in PE there are many different formulations and moleculear weights with varying characteristics. Newer multi-layer co-formulation containers have much higher MTR. Storing in controlled conditions.......ala 70F; 50% relative humidity.....will greatly contribute to the container contents maintaining characteristics. Stable....non-varying...conditions are very important as well. Containers of 20 years ago are primitive compared to today's specialty formulations. But, PE is still PE. Bottom line......it depends on how they were stored.
 

jpndave

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Wouldn't Oxygen exposure also be a concern along with the mentioned temperature and moisture? Along those lines, the RL powders are packaged in extremely large containers for what is in there - lots of extra space. 16lbs easily fits in an 8lb bottle. VV is not so much that way, much better matched. I suspect they do that to allow the powder to be packaged easily and then settle over time/transit. Also, one bottle size covers many different powder densities.

I could be wrong but it seems to be storing the powder in bottles with less air would be better. It also takes up half as much space on my shelf. So I just got some RL26, 8lb bottles, case packaged with two bottles from same lot, same #. Combining those should be fine if not even better to limit air in the bottles. Thoughts?
 

Jed Cooper

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Makes sense. Years ago I used to store my powders in new 1qt mason jars(should be best) but now I'm too lazy to do that. lol
 

Mike Matteson

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Jun 26, 2017
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I get powder from time to time and store it and not having a problems. I hate to do that, but anymore when the powder comes up you have to buy, just to have it on hand. Primers are the same thing. Try and get powder and primers now. This last round of crap going on, has taken everything off the shelves again. 22 ammo kind or gotten back in stock and it's gone too. The manufactures know what to do either. Make to much and it sits, not enough everybody complaining not product. When you are getting from 70 to 150 rounds out of a pound of powder it doesn't go very far.
 

J E Custom

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As promised, here is another article On the moisture content effect on Smokeless powders.

).

J E CUSTOM
 

J E Custom

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Wouldn't Oxygen exposure also be a concern along with the mentioned temperature and moisture? Along those lines, the RL powders are packaged in extremely large containers for what is in there - lots of extra space. 16lbs easily fits in an 8lb bottle. VV is not so much that way, much better matched. I suspect they do that to allow the powder to be packaged easily and then settle over time/transit. Also, one bottle size covers many different powder densities.

I could be wrong but it seems to be storing the powder in bottles with less air would be better. It also takes up half as much space on my shelf. So I just got some RL26, 8lb bottles, case packaged with two bottles from same lot, same #. Combining those should be fine if not even better to limit air in the bottles. Thoughts?

Just the way I prefer to buy powder.

When I need powder of some brand and burn rate I prefer to Buy 1 Pound containers with the same lot numbers, On some of the big magnums that consume lots of powder, I will try to find as many 1 pound containers (6 to 8 With the same lot # if possible) Then I store them in a good storage environment and use out of one can at a time leaving the others sealed from the factory.

I had found that the 8 pound canisters that were opened every time i loaded ammo became slower. and that using out of the smaller containers it was only exposed to the humidity 2 or 3 times keeping the rest at the constant moisture the factory intended it to be.

I still have 2 1 pound containers with the original H 4831 that Hodgdon started with by pulling 20 mm surplus ammo and selling it to the public. It was the best powder I have ever used and kept it/guarded it with my life, 👍 for the 1000 yard matches. It has to be 70 to 80 years old and is still in good shape (I hope) because I won't open it until I need to load it. it appears to be a little milder that the new stuff and could be because over the years in a high humidity environment even though it has been stored in a plastic containers that the moisture content has risen slowing the burn rate.

I also don't recommend mixing powder for many reasons that are posted in earlier post. So Store powder in the original container and don't open it until you need more than you have left in a used container.

May sound picky or unnecessary to some, But consistency is the constant in accuracy.

Just my method for powder storage that has served me well.

J E CUSTOM
 
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wonderman4

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Oct 7, 2013
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South Texas
My understanding is the deterrents degrade by exposure to moisture. When the deterrents degrade, the burn rate changes. Some times enough to make a drastic difference. This is the reason that ball powders don't generally have the life span as extruded powders. Ball powders need a lot more deterrents.

Most Hodgdon powders are packed in 60% humidity, per reps from Hodgdon.

Never vacuum pack loaded ammo. The moisture will be drawn out and the resulting burn rate of the powder will make your safe loads dangerous.
 

kenfairley

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Mar 1, 2012
Messages
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As plastic containers are porous to moisture, why do we keep using the OEM plastic instead of glass and metal lid containers such as Ball Jars that are not porous? Zero moisture transfer and could be stored anywhere
 

Ol' Red

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Nov 28, 2018
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Location
Wyoming
Just the way I prefer to buy powder.

When I need powder of some brand and burn rate I prefer to Buy 1 Pound containers with the same lot numbers, On some of the big magnums that consume lots of powder, I will try to find as many 1 pound containers (6 to 8 With the same lot # if possible) Then I store them in a good storage environment and use out of one can at a time leaving the others sealed from the factory.

I had found that the 8 pound canisters that were opened every time i loaded ammo became slower. and that using out of the smaller containers it was only exposed to the humidity 2 or 3 times keeping the rest at the constant moisture the factory intended it to be.

I still have 2 1 pound containers with the original H 4831 that Hodgdon started with by pulling 20 mm surplus ammo and selling it to the public. It was the best powder I have ever used and kept it/guarded it with my life, 👍 for the 1000 yard matches. It has to be 70 to 80 years old and is still in good shape (I hope) because I won't open it until I need to load it. it appears to be a little milder that the new stuff and could be because over the years in a high humidity environment even though it has been stored in a plastic containers that the moisture content has risen slowing the burn rate.

I also don't recommend mixing powder for many reasons that are posted in earlier post. So Store powder in the original container and don't open it until you need more than you have left in a used container.

May sound picky or unnecessary to some, But consistency is the constant in accuracy.

Just my method for powder storage that has served me well.

J E CUSTOM
JE, Is that old H4831 in a metal can with a red and yellow label?
 

jimisbell

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Jul 24, 2020
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ingleside, TX
Why plastic or metal instead of glass? Probably the same reasons that Federal law doesnt allow gasoline in glass containers....LOL. I wouldnt want it in glass anywhere near me where a broken bottle and a spark could set it off.
 

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