best ‘moisture absorbing’ fabric?

my question is do you care about water in vapour or liquid form. If you care about liquid, then cotton is pretty good. I found it to be better than wool during some my informal experiment about water retention a few years ago… though I would hope someone has more rigorous data than this basic test.

Mark, I am interested mainly in water in vapor form.

What about silk or SoySilk?

Huzefa, are you thinking about a wicking layer for a single skin tent? I was considering this too. Maybe silk layed on the bias so that gravity helps the condensed water downwards?

Rog, I am looking for a material for a 'condensation curtain' in single wall tent. Basically a curtain hanging from the front pole on your chest leaving other part of the tent condensation free.

A sandwitch layer of silnyon and wool would work great leaving the moisture from your breath the option of either getting absorbed or vent out.

>Maybe silk layed on the bias so that gravity helps the condensed water downwards?

Not sure I understand you. In sub freezing conditions I expect vapour to freeze in the fabric itself.

If the water in this chest curtain is frozen stiff then you've stopped breathing. ;-)

In sub zero conditions I find that sleeping on my front and breathing into a wool scarf or microfibre towel which I can air dry on the trail works for me. Keeps my nose warm too.

I guess a microfibre towel might work as a dual use chest curtain too.

Don't forget you pass perspiration through the lower half of your sleeping bag too, so if your wool/nylon sandwich is a two layer thing, you may get condensation dripping off the silnylon onto your sleeping bag in the chest area.

Rog, microfiber towel is a cool idea. But right now I am dropping this sandwitch layer idea. A large Towel is too much weight. Instead a better idea is to use psolar mask. It has a module that captures the water vapor and returns it to the air you breathe.

You planning on tackling the himalaya Huzefa?

Interesting product, how much does it weigh with enough spare dessicant for a three week trip?

Rog, yes I do plan to do lot of hiking and mountaineering in himalayas in coming years and I want to do it UL way.

After reading several reviews at backpackgeartest.org/ I realised that it doesnt absorb any water vapor: it is simply a heat mask which does a ok job of rebouncing vapour back into your breath.

edit:
I read about desiccants. I wouldnt mind wearing a mask with desiccant in it. But I dont find it practical for long trips. Instead a better idea would be an oxygen mask with a hose attach and having the other end outside the tent. This idea has been discussed before in another tnread. It has to be short so that heat from breath prevent frost inside the hose. I will talk to my doctor and see if I can get one.

Commercial DRIERITE is anhydrous calcium sulfate. It is of neutral pH, constant in volume, chemically inert except toward water, insoluble in organic liquids and refrigerants, non-disintegrating, non-wetting, non-toxic, non-corrosive, non-channeling, generally recognized as safe (GRAS) by the FDA, not regulated by OSHA, economical to use, and can be regenerated repeatedly for reuse. Uses include drying organic liquids, polyurethane reactants, gases and solids.

This stuff is cool. Dessicants like this caso4 or silica gel can be packed into a can connected to the hose. Moisture from the air exhaled and inhaled *only* will be absorbed by the dessicant in the can. If only now I can find out how much moisture I give out at night I can pack amount of dessicant accrodingly.

I guess this is just another crazy idea.

I like that you're thinking out of the box, but I think a desiccant would be counter productive. Cold air is very dry, and all the cold weather masks I've seen involve ways to trap moist (and warm) air to be re-breathed. I think you would have a parched mouth in a matter of minutes unless you had a valve. Even then, I think you'd be better off using proven technologies. Not to mention this desiccant can is probably not light.

I wasn't able to find any information on the quantity of water lost via respiration at any given temperature. But, I found some mask ideas here: http://dynamics.org/cryo/COLD_GEAR/

Jaiden, thanks for the comment and sharing that link.

You are right. In its present form it certainly is counter productive. Dessicant will dry inhaled air; it could even be hazardous.

The problem can be solved by a Non-Rebreather oxygen Mask.

This one is different from other masks I have found which cover your mouth. Breathing through mouth doesnt add moisture to the air. You simply have to cut off the bag. The exhaled air is passed out through the one-way valve.

Dessicant cannister doesnt have to be heavy. A poly bag will work. Infact placing the other end of the tube inside your sleeping bag can provide additional warmth.

If i understand it right, the psolar mask uses dessicant too. But not to dry incoming air.

http://www.psolar.com/faq.html

Does the facemask get wet and gooey and icy?
No. The module captures the water vapor and returns it to the air you breathe. The moisture management is handled by the heat exchanger – not the fleece. Breathing humidified air puts less stress on your body.

Is the desiccant safe?
Yes! The desiccant is bonded to the plastic and is not inhaled. The desiccant is used in baby powder and it is also used to thicken milkshakes.

How easily you'd get to sleep wearing one is another question they haven't answered in the FAQ however. ;-)

Ok. here is what I found.

http://groups.google.com.pk/group/bionet.biophysics/browse_thread/thread/ca34bbc6ee43c37f

The only cite I can find, says that an "average" person exhales approximately two liters of water into the air in 24 hours.

So if you are sleeping for, say 6 hours, you will release 500ml or 500gms of water.

According to the data here-
http://www.sorbentsystems.com/desiccants_charts.html

-molecular sieve seems to be the best dessicant. It is reusable by simply heating it. I have found a seller for molecular sieve:
http://www.vonheltzen.com/sieveinfo.html

According to his website molecular sieve will absorb 25% of its weight in water. So you need 2 pounds of the material to absorb all moisture from your breath. :)

The desiccant is used in baby powder and it is also used to thicken milkshakes.
I think it is cornstarch.

I foung another cool stuff.
http://www.zorb-it.com/usermods/technicalinfo.asp

Instead of bringing the relative humidity level to 0% this stuff maintains a constant %RH. The website says this works forever. An UL mask can be made using this stuff. The moisture from exhaled air will be absorbed and returned to the inhaled air.

I will also take another look at those masks at Jaiden's link.