The short term exposure test is something I’ve done hundreds of times and the results were not surprising at all to me. It was more to provide a visual representation, instead of me just stating things. This long term test is something I haven’t specifically done, in this exact way, and the results were a little surprising. I’ve done different long term tests, and have lots of real world experience with down and moisture in a long term setting….but I haven’t done this specifically.
I was really surprised by how little the down chamber absorbed while in contact with water. I expected to come back and see the down chamber had sucked up a bunch of water and flattened out. However, just being in contact with water for a long period of time did not result in catastrophic loft loss. There was loft loss, but not as much as I would have expected. The catastrophic loft loss only came when the wet chamber of down was compressed.
I think I have a good idea of what is going on and I might do a follow up video to help visualize it. Basically, each plume of down is like a little snowflake where there are all these fibrils, or little branches, that hold up loft. The chamber is mostly air, with these little fibrils holding up the space. Even though down plumes are hydrophilic, those are really narrow pathways for water to travel along. So the outer shells can be pretty wet, but the moisture has difficulty really moving through since there are only these narrow pathways for it to travel along. However, once there is mechanical compression of the chamber, the air is pushed out and the mass of down is compressed into a mass. Once that water can make contact with a denser mass, it soaks in and those plumes can’t loft back up. They are pushed into the moisture and stuck flat.
While this is super interesting, it isn’t necessarily a functional revelation. We can’t really not compress our down items. I guess it could be useful in a situation where you know you have gotten a down item wet. You could choose to leave it uncompressed and dry it before compressing it, since compression seems to be what result in that lumpy wet mass of down. However, most of the time, you don’t have the option of setting your uncompressed down item out to dry. You kinda have to pack up and get moving, and that packing up will result in that moisture spreading through and preventing the down from re-lofting later. I guess maybe we could choose to not compress it as hard, and assume that the spread and loft loss would be limited.
We should keep in mind that this is not a controlled lab setting, and even as an amateur test, it isn’t actually an exact depiction of real world scenarios. Putting little test chambers on top of a bowl of water seems like it would simulate real world moisture loads, but there are always variables that we don’t know about. I think it is likely to be a relatively decent simulation of shell wetting issues like tent wall condensation transferring to sleep systems, or shell moisture soaking into puffy garments while sitting out in precipitation. However, internal condensation build up issues from overnight use, might have much different effects since that is moisture settling within the down loft somewhere, instead of soaking in from the shell. This might also be a good depiction of this…..I can’t really say for sure.
This same test was done with 900 untreated and 900 Expedry. I’ve always felt that hydrophobic treatments of down aren’t all that effective in a substantial way. They can show some difference, in certain tests, but in real world cases, the difference doesn’t seem to really show up as substantial benefit. That is my opinion and it doesn’t necessarily mean that there aren’t different use cases and people where it might make a substantial difference. However, this test seemed to align with my opinion. The two chambers fared about the same, regardless of whether it was treated or not treated. There seemed to be a very slight advantage to the Expedry, but it was very slight. In the past, my rationale was that if the treatments weren’t that effective, I’d rather just not have it. Those treatments were PFC-free, so a less toxic option than the previous, but still. There is something there that doesn’t do much, and can wash out. With Expedry, it is supposedly a permanent treatment with lower up front resource expenditure, so I’m more ok with it being there, even if it isn’t doing that much. If it’s not hurting anything, then might as well have it there in case it can make a difference. This is simply me forming opinions as I move along. There may be more information that comes out that changes my perspective.