After the last round of testing down performance in wet conditions, the take-away was that the loft loss that happens when down gets wet, happens when wet down is compressed. If the trapped air in a lofted chamber is maintained, it’s rather difficult to get it wet. You can dunk a lofted chamber under water and it doesn’t get very wet. You can even leave it right in water for long periods and it doesn’t absorb much. If you compress it while it’s wet, it stays flat until you dry it for an extended period.
This begged a re-evaluation of when and where down should be used. The glaring question, to me, was ” Can you get a down jacket wet, but maintain loft, as long as you don’t compress it?”
Technically, I think, the answer is yes. If you did not compress any down, you could get it wet and still maintain loft. However, there are a million accounts of people wearing their down coat out in the rain, only to end up with a flat, cold, wet noodle, after. My assumption was that the act of wearing the garment inevitably compresses some of the down and, if that down is wet, it will stay flat.
To test this, I took a down jacket, which I intentionally stuffed to high density to resist loft loss from moisture, out for a hike/run in 15f conditions. I wetted an Alpha Direct hoodie mid/base layer, which I wore under the down layer, to create moisture content. I wetted it in a sink but squeezed and spun out most water so that it was not dripping wet, but moist. My body would, not only produce moisture, but the heat would push the moisture in the hoodie, out into the down layer. Meanwhile, the cold temps outside are pushing from the other side, preventing heat and moisture from moving all the way through. A dew point was certain to exist inside the down garment.
I did about a 5mi loop, which begins with a steep climb up to Cornell campus, does a small loop, and then heads back down the hill. I jogged the climb and part of the uper loop. Then hiked the back half of the loop and the downhill. As predicted, the parts of the jacket that were not under any compression, like the torso chambers and back chambers, remained fully lofted, even with a pretty heavy moisture load. The parts of the garment that are under compression saw significant loft loss. So much so, that I noticed the fit of the garment change. Loft will take up part of the length dimension in a garment. If that loft collapses, the length extends. I could feel the sleeves start to hang longer and heavier. This is because one of the areas that saw loft loss was the sleeves, particularly around the bend in the elbow. This area inheretly encounters compression as the sleeve bends with arm movement. The chambers around the elbow compress the most and these ones became quite flat. Also, the arm pit area where the sleeve/arm compress against the torso. These also became quite flat. The other area that lost most of its loft was the shoulders. This area supports the weight of the garment against my shoulders. The upper chest, back, and the top of the shoulders were VERY flat by the end of the test.
The shoulder area was the worst effected. Again, most of the torso/back held loft. Most of the sleeves showed varying dgrees of loft loss, from pretty bad at the elbow, to not bad at the forearm. The hood saw some noticeable loss. Likely because it is cinched against my head a bit, which caused compression as I moved.
So…..I guess it’s back where we started. The prevailing sentiment about down performing poorly in moist conditions, holds true. There are known exceptions. For instance, the overbag scenario. In this case, your adding insulation over top of a down sleep system, which raises the temperature beyond a point where moisture could accumulate. There is moisture present, but the temperature forces it beyond, such that you can get away with having down loft with moisture around.
Another case could be sleep systems without an overbag, which are dried in the morning. Ideally, sleep systems should not be rolled in and compressed…rather the sleeper moves inside it. In this case, you could accumulate moisture overnight, without loft loss if you aren’t compressing any part of it. It becomes a problem if that wet system is packed away, but if it is set out to dry before packing, one could manage moisture this way. The issue, for many of us, is that good drying conditions in the morning are rare.