Storing Cigars in an air tight container ?

[Scimmia]

Originally Posted by Pyro

But, the question is, if you replace air with water vapour in a closed container containing cigars and some humidifier, can anything but 100 % RH exist inside that container, regardless of gas pressure and/or temperature?

Absolutely. If you have standing water in any closed system, it will exist at 100% RH (or so), again, regardless of the presence or absence of air. That's why we use chemicals to regulate the humidity to what we want. If you just had a wet sponge or something, it wouldn't work. With PG or treated beads, a chemical is keeping it in equilibrium. With raw beads, it's keeping at Equilibrium Moisture Content for the beads/cigars.

[duhman]

First off, air doesn't "hold" moisture, we need to get that out right away.

We are actually in agreement, just looking at it from a different point of view.
Air = vacuum with added vapor pressure.
More vapor pressure = more water capacity.
That chart is water capacity per temp. Water capacity is given in grams per kg of air.
RH is percent of saturation at a given temp and density.
A low pressure vessel would saturate with less water, therefore at 100% RH there would be less water vapor.
If you took a sealed vessel with 50% RH vapor in it and cooled it below the dew point it would condense water out. The RH would shoot to 100%. There would still be the same amount of water in the vessel. If you warmed it back up, the water would evaporate again.
Air compressors have a problem with this because the air expands going into the holding tank, condensing the water out. It's always 100% humid in the tank, like you said.

[Scimmia]

We really aren't in agreement, as my position is that this is totally false:

Originally Posted by duhman

More vapor pressure = more water capacity.
That chart is water capacity per temp. Water capacity is given in grams per kg of air.

There is no "water capacity", water vapor will exist at the same levels regardless of pressure of oxygen, nitrogen, etc. Grams per kg of air makes no sense at all given the links I provided, considering you can have water vapor with no air whatsoever. According to your chart, that's not possible. My guess is that this chart should be grams per cubic meter.

[Pyro]

Now I understand what I was missing! The techniques discussed here using vacuum sealing does not rely on underpressures strong enough to create the potential problems I was thinking about.