Originally Posted by vampiresmiley
For best breathability in the very low temps, my canvas winter sock is great. With using VB clothing at night, and making all effort to keep the down dry, the last thing I want is to trap water vapor inside my hammock sock or rain down frost trying to get out. Obviously the canvas comes at a significant weight penalty, so I only use it when I'm also pulling a sled.
I have not tried experimenting with a frost bib to help capture some of the moisture from breathing, that may allow for use of the lighter but less breathable fabrics. In the cold I tend to stick with what I know will work.
I have used a simple nylon sock in cool weather when more ample venting is easier and cold protection not as critical. Though, I would like the option of a packable cold weather sock for times/areas when it would be best to leave the sled at home.
If you're using VB clothing, the only source for condensation will be your breath. From my experience, frozen breath will condense on the upper part of the sock and not on the insulation. In essence, the frost point is moved from your insulation to the sock (which is not a bad thing).
If temps are low enough for your breath to freeze on the upper part of the inside of the sock, chances are the relative humidity is low enough to just brush what ice there is off of your insulation. The DWR on most quilts will repel that type of moisture. It's the moisture generated from insensible perspiration that will get stuck in your down. VB should eliminate that.