I may be done with my Chameleon Top cover...

[WV]

Water vapor leaving your body passes through layers of insulation where the temperature gets cooler farther from your body but doesn't get cold enough for the vapor to start condensing (mostly). There are breathable fabrics, like Pertex Microlight and Momentum 90 that have more surface area on the outside (they're slightly fuzzy) and thus help any vapor that has condensed into liquid state evaporate into the surrounding air. If it then encounters a colder surface farther up, it can condense again, and even freeze. I had a sock-tent made of Pertex that did pretty well at helping moisture find a better place to condense and freeze. After very cold nights, there would be a small amount of ice crystals on the inner surface of the sock-tent just above my head, but quite a lot of ice on the outside of the fabric. My sock tent also didn't touch the hammock, so it was easier to sweep any interior ice off to the side. I'm told that mountain climbing tents have double walls so the ice forms on the inside of the outer surface, but not on the inner layer. In the morning you shake the tent, and the ice falls to the floor between the tent layers and you sweep it out the door. (Or, so I was told. The principle makes sense, in line with my other experience.) It's all touch-and-go, as Shug would attest. You've gotta love fine-tuning your setup.

[cmoulder]

The only way to totally eliminate ice build-up in extreme cold is to wear vapor barrier clothing and breathe through a snorkel... a tube with a couple of simple flap valves for intake and exhaust (tube to the outside of the shelter) in the mouthpiece. Intake would not require a tube if there is some fresh air ventilation.

Jack Stephenson (of Warmlite fame) was known to expound on this frequently and at length, and it was he who helped Will Steger address the serious condensation issues he confronted during his polar expeditions.

The snorkel might sound silly but if I were a serious adventurer spending protracted amounts of time in deep cold I would absolutely experiment with the concept.

[lorazepam]

The only way to totally eliminate ice build-up in extreme cold is to wear vapor barrier clothing and breathe through a snorkel... a tube with a couple of simple flap valves for intake and exhaust (tube to the outside of the shelter) in the mouthpiece. Intake would not require a tube if there is some fresh air ventilation.

Jack Stephenson (of Warmlite fame) was known to expound on this frequently and at length, and it was he who helped Will Steger address the serious condensation issues he confronted during his polar expeditions.

The snorkel might sound silly but if I were a serious adventurer spending protracted amounts of time in deep cold I would absolutely experiment with the concept.

While reading this thread I was wondering if a modified cpap mask could be used to direct exhaled air out of the hammock.

[PappyAmos]

While reading this thread I was wondering if a modified cpap mask could be used to direct exhaled air out of the hammock.

I modified my Chameleon top cover to have a much larger vent. Have frost bib (a la Shug.) So far my CPAP exhaust has pretty much gone out the vent because it goes that general direction anyway. Only been down to 28° so far with this setup.

[OneClick]

The snorkel might sound silly but if I were a serious adventurer spending protracted amounts of time in deep cold I would absolutely experiment with the concept.

Man, I've been joking about that since a winter trip in 2009 where I just thought it would be cozy to get 100% inside the sleeping bag. Before the days of actually getting a wet bag/quilt, which I've been experiencing more and more.