Question on drying sleeping bags in winter

[Travis Leanna]

Here's my question:

After waking up, will it do any good to compress and squeeze all of the moist air out of the bag and then let it reloft and sit out to dry while packing up camp? Obviously with weather permitting.

[Bob Gross]

Synthetic or down?

I use down, so I can't say about synthetic. With a down bag, I exit the bag, turn it inside-out, and then try to lay it out in the sun or over a rock. It seems like compressing the bag would drive the moisture deeper.

–B.G.–

[Dale Wambaugh]

I think the op is pondering using a bellows effect to make an attempt to get moist air out of the bag in the hope of getting drier air back in. It is a noble thought, bu I think the tight weave of a down bag will spoil things and Bob is probably right about doing more damage than good. Getting it out ominous the sun and shaking it now and then is my advice

But what to do if there is no sun? The sun theory is great for areas with cold dry air and little precip, but it is weak in places like this:

We have kids out here who have reached puberty without seeing direct sunlight and have never had a sunburn!

[Hiking Malto]

Travis,
The bellowing effect would remove some of the moisture that is trapped in the bag as vapor, in the layers between the inside and the dew point. This would theoretically be more effective if done immediately upon exit since allowing the inside layer to cool down would condense the vapor. While this is the theory, I doubt it would have much effect in reality since I suspect the ratio of vapor to condensation in a bag overnight would be low. This winter I have have started wearing my cuben rain pants and pu coated nylon booties and the moisture has been greatly reduced. (Sometime also wear the cuben rain jacket.). This system works for me because I generally start my day before the sun comes up and rarely stop for more than a few minutes during the daylight hours. This doesn't allow me to follow Bob's drying method so it is easier to avoid putting moisture in vs getting it out.

[Dale Wambaugh]

One technique use by early risers is to put their damp sleeping bag out in the sun to dry during their midday break. That is usually a summertime technique and in open areas.

Using Cuben "pajamas" as a VBL sounds interesting.

[Tipi Walter]

People often look at their fantastic WM down sleeping bag at home and marvel at its loft and warmth. Then on an 18 day trip with day after day "exposure" they wonder where all that great in-home loft went—at least they do if they live in the Southeast mountains.

Some days are worse than others due to air humidity etc.

So, it's vital on a long trip to pull out the bag in the morning and hang it out—the bear line works great for this. See below fotog. Even if it's 0F and the bag has a glazed donut of frost on its shell it's important to hang it out and let the wind do its job. Sublimation or evaporation or whatever it's called.

[Author]

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