Are powders hygroscopic?

[Jed Cooper]

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.

 

[J E Custom]

The plastic bottles are the best containers for powder storage as long as the lids are one tight and sealed. All powders are hygroscopic if left open to the air. If the seal is not good they will degrade
and become acidic. Powders have a controlled moisture content and it should be protected as much as possible by proper storage at a constant temperature if possible. the plastic containers don't wick moisture so even when using, keep them closed as much as possible.

Over time powders will degrade because of the existing moisture content but with minimum exposure to air and good storage, it will last many years.

J E CUSTOM

 

[JMW67]

I have some that are 18 to 20 years old and are still fine , they have been stored in climate controlled building with very low humidity building stays at a constant 72 degrees and once opened a dessicant is put in the container

 

[jimisbell]

Very good to know. I have some Green Dot in an unopened container that I have had for 18 years. I am pretty sure it is good. But it IS in a paper container. My old SR4756 is in a sealed plastic container.

EDIT: I just realized that the Green Dot is from 1965, the Watts Riots. 55 years!

 

[Pdvdh]

I currently have some Hercules 2400 from the 1960s. Still use it. Still good. Provides the same MV per charge weight as the current Alliant 2400. It's 50+ years old.

On the other hand, I stored some IMR4350 in a garage with big temperature variations, and it went acidic within about 10-15 years. Even though it was never opened. Go figure... Used it for fireforming wildcat casings.

 

[Pdvdh]

I believe powder can be degraded by water vapor, such as exposure to high relative humidity air.

 

[Dosh]

The plastic bottles are the best containers for powder storage as long as the lids are one tight and sealed. All powders are hygroscopic if left open to the air. If the seal is not good they will degrade
and become acidic. Powders have a controlled moisture content and it should be protected as much as possible by proper storage at a constant temperature if possible. the plastic containers don't wick moisture so even when using, keep them closed as much as possible.

Over time powders will degrade because of the existing moisture content but with minimum exposure to air and good storage, it will last many years.

J E CUSTOM

If "powders have a controlled moisture content", can a powder become too dehydrated? It's bone dry here in Az, could my powder be in danger?

 

[LVJ76]

If "powders have a controlled moisture content", can a powder become too dehydrated? It's bone dry here in Az, could my powder be in danger?

If you keep it in a cold and dry place you'll be fine.

I have some IMR-4064, 4350 and 4895 thats is 10+ years old and still works like new. Constant temperature of 71 degrees and with silica packs.

 

[LVJ76]

Meant cool not cold

 

[J E Custom]

If "powders have a controlled moisture content", can a powder become too dehydrated? It's bone dry here in Az, could my powder be in danger?

From what I understand, a dry climate is better, but still but needs to be kept away from powder to prevent it from being to dry Increasing the burn rate. It should be stored in a cool dry space with the container sealed. The higher the moisture content, the slower the burn rate.

I have heard of people placing Silica jell packs in powder to reduce the moisture content and this could actually dry the powder out to much and in effect cause it to change the burn rate to faster so it is not recommended. Stored in a cool dry cabinet/storage in the original container is still best.

J E CUSTOM

 

[LVJ76]

From what I understand, a dry climate is better, but still but needs to be kept away from powder to prevent it from being to dry Increasing the burn rate. It should be stored in a cool dry space with the container sealed. The higher the moisture content, the slower the burn rate.

I have heard of people placing Silica jell packs in powder to reduce the moisture content and this could actually dry the powder out to much and in effect cause it to change the burn rate to faster so it is not recommended. Stored in a cool dry cabinet/storage in the original container is still best.

J E CUSTOM

You Sir are correct on the silica packs, should not be placed inside the powder container but outside around the containers.

 

[MagnumManiac]

I find this interesting, in most cases, it is the ether, alcohols and solvents evaporating that decreases the energy of the powder over time.
I have seen IMR take a quantity of the first batch ever made of IMR4064 from a container filled with powder that is covered with WATER.
They dry it out and test it against newer batches to see if the recipe stays the same.
If powders were hygroscopic, why would IMR store the powder in water?
I have never seen any real evidence that powders are hygroscopic, only anecdotal tales of such. None of the MSDS mention moisture other than the solvents used.
Yes, there is a moisture content %, but no where does it say this increases with exposure to air. It is the solvents degrading that causes powder to go bad, not moisture.
Anyway...battle on.

Cheers.

 

[243winxb]

Plasticizers in smokeless powders reduce hygroscopicity. Examples of plasticizers include nitroglycerine, dibutyl phthalate, dinitrotoluene, ethyl centralite, and triacetin.

Composition of smokeless powders can be seen as an SDS (safety data sheet) provied by manfactures.

https://hodgdon.com/resources/safety-data-sheets/

 

[J E Custom]

I find this interesting, in most cases, it is the ether, alcohols and solvents evaporating that decreases the energy of the powder over time.
I have seen IMR take a quantity of the first batch ever made of IMR4064 from a container filled with powder that is covered with WATER.
They dry it out and test it against newer batches to see if the recipe stays the same.
If powders were hygroscopic, why would IMR store the powder in water?
I have never seen any real evidence that powders are hygroscopic, only anecdotal tales of such. None of the MSDS mention moisture other than the solvents used.
Yes, there is a moisture content %, but no where does it say this increases with exposure to air. It is the solvents degrading that causes powder to go bad, not moisture.
Anyway...battle on.

Cheers.

This is just one example found on the subject of the effects of moisture content of smokeless powder. There have been more examples/articles, and when I find them i will post them.

https://www.vihtavuori.com/know-powder-moist-content/#:~:text=Variations in moisture content change,because of the added nitroglycerine.

Powders are made using water to mix the components, then they are dried to an exact moisture %/content for burn rate performance and then packaged

J E CUSTOM