Without any question, that is true, and is exactly what I have always said. We agree on that, and always have. Hence my use of frost bibs(usually) inside of any sock, regardless of vent holes or breathable material. Using a sil-nylon UQP, or perhaps to a lessor degree any UQP, without the use of another interior, warm, VB , can obviously lead to trouble. Many people do not understand this concept, and thus they get the predicted condensation when their vapor contacts the COLD layer that is farthest from their body and is at or below the dew point. Lack of understanding of these basic law's of physics no doubt contributes to the unpopularity of such products, as most demand maximum breathability. But, I'm sure you are aware that there are some people who even complain of condensation even with breathable UQPs.Originally Posted by SilvrSurfr
In fact, there is fairly consistent condensation inside of our breathable quilts- unrealized on short trips with sunshine, as it is absorbed in the down and most people do not weigh their quilts or measure loft to put the breathability to the test. Some one here ( CMoulder? not sure) just weighed their quilt after one night and 35 minutes drying time, and I think the weight increased a bit over an ounce? That would be from condensed body vapor- unless it was absorbed sweat. A few nights of that could make a difference, especially if you don't start out with quilts rated 10 or 20F lower than the lowest expected or likely temps, as some folks here routinely do. Me, I routinely use quilts under rated for the lowest likely temps, and sleep dry and toasty.
Also, on the Shug's example you used, were his socks/over covers with vents made of breathable material, or not? Breathable, right? Of course! And yet even with vents he still needs a frost bib? Yes he does, because it is irrelevant whether that material can "breath" once it is below the dew point. Just as it is irrelevant that his frost bib is extremely breathable fleece, it still collects massive condensation. At some point, breathability becomes a fantasy. And that point is when our quilt shells- or even worse, 1/4" inside our quilt shells, drop to the dew point. Have you ever slept out under the stars and woke up to a thick layer of dew or frost encasing your TQ shell, when there was not much sign of dew any where else? I have. One more about Shug's tests(please correct me if I'm wrong, Shug): do you remember one of his pod tests, when he opened up the layers of his very breathable stacked quilts, and had not just some dampness, but actual frost inside one of those layers? Don't be in denial about the fact that you get some condensation inside your breathable quilts, because a little or a lot, depending on conditions and length of trip you do.
Reply With Quote
). I try to get to Mt. Rogers each January, if only to keep myself a little bit in touch (and to find out what Hickery and Slowhike have been up to.) The past few years I've relied on having one side and one end of my over-sized Ogee tarp staked down to block prevailing winds, rather than using a sock-tent. When I had my best winter set-up, some years back, it had an insulated sock-pod, then a Pertex fabric sock, then a tarp. Air temperature inside the sock tent was often 40 degrees + when it was below 20 outside. That heat was produced by me and a dog, with some help from hot water bottles. The best part of that system was that the water vapor given off by me + dog passed through top quilt and sock-pod before it condensed on the Pertex sock. That fabric, like some others, such as Momentum 90, has much more surface area on the outside (slightly fuzzy) than the calendered inside suface. Water (recently condensed from water vapor) travels the short distance to the outer surface by capillary action, where it freezes. I would typically find considerable frost buildup on the outside of the sock and only a tiny bit on the inside. Believe me, outside is better. It avoids mini-snowstorms inside the sock when you start to move around.
Bookmarks