Downtek

[Greg Mihalik]

"I wonder …"
"… do you think…"
"I would guess…"

Make up anything you like.

[J-L]

It's called a guess, based on how every other DWR item performs. Per Andrew Skurka's book, "DWR is degraded by abrasion, dirt, and body oils". Why would the coating on down not degrade in the same way?

Greg, "I wonder" and "do you think" is not me making anything up, it's me asking a relevant question.

[David Ure]

"DWR is degraded by abrasion, dirt, and body oils"

Indeed it is. However, that is for fabrics that are next to skin, dirt, or rock. The down is reasonably protected, albeit some body oils can eventually make their way into the down. But we are talking a long time of use. I just can't see those issues affecting DownTek.

However, I could be wrong so this is why sources are so vital specific to water resistant down.

The bigger issue would be if the down becomes damaged via the water roofing process thereby reducing its lifespan.

[Bob Moulder]

After some mondo googling sessions to try to find any objective testing – and coming up with none – I decided to stick a toe into the shallow end of the pool and bought the EB FA Downtek hooded jacket, thanks in large part to Eric B's enthusiasm for EB Downtek stuff, and its very reasonable price.

I proceeded to wear it practically every day, using it sometimes to walk the dog in heavy mist/light rain for up to 45 minutes, just to see how the external DWR worked, whether loft was maintained and how quickly it dried out. I have used it on several 1- and 2-night trips, a couple of times purposely donning the jacket over a fairly damp fleece and shell combo, which is under normal circumstances a real no-no. I did this in situations where a hasty retreat from the hills was possible if a hypothermic disaster was in the making. (I've been on trips where wet down coat and sleeping bag put an end to the trip.)

Of course, my observations are purely anecdotal and the information is truly valuable to only 1 user – me – but I am fairly certain that in general it performed noticeably better than non-treated down would have in these practical exercises. Relative to my experiences with other down garments, it seemed to dry out faster than I expected and did seem to maintain loft better.

Based upon what I've seen, I would wade into the pool a little further and purchase a Downtek SB, if only I were in need of another bag, which I am not.

But it still surprises me that there has been precious little independent, objective testing of this stuff. Plenty of anecdotal stuff (which any of us can generate) even from the likes of Backpacker magazine (yes, LOL)… where science and objectivity are routinely crushed by ad dollars.

[Jerry Adams]

"I've been on trips where wet down coat and sleeping bag put an end to the trip."

How did your sleeping bag get wet? How wet was it? Did it lose most of it's loft?

I've been using down sleeping bag for a year and never had a problem. Just trying to anticipate a worst case.

[Bob Moulder]

How did your sleeping bag get wet? How wet was it? Did it lose most of it's loft?

Winter in the Whites of NH, where it can be very cold and very humid at the same time. Using no VBL, overnight condensation in bag, impossible to dry out in the morning, stuffed, repeat 3 times, and subsequent loss of a huge percentage of loft… like 70-80% loss. Voila!, your -20 bag is now a +20 bag.

I think the worst we ever encountered was -10F and rain near Mt. Guyot. Of course the rain instantly froze and we found ourselves in a snow quagmire with 1/4" ice crust on top of 2+ feet of powder. Very tough to snowshoe in that. Sometimes it's best just to go home.

Would Downtek help in these conditions? I dunno.

[Jerry Adams]

Thanks Bob. So, were you in a tent? How cold was it?

I never go below 20 F or so, so I never encounter conditions like that.

[Bob Moulder]

Yes, in a Bibler Eldorado. Lows -20 to -25 or so. It was a nightmare trying to get the ice crust off the tent. A couple of tents collapsed during the night.

Coldest I have ever experienced is -33 in the Adirondacks. I think it was a little colder where we were (Opalescent creek IIRC), but that was the official temp in Keene Valley. Downtek or no Downtek, when the water vapor reaches the shell in such temperatures it's gonna stick, so VBL is necessary for longer trips.

[Andrew F]

One of the two DWR down bags I own is a 5F winter bag. My hope in getting the DWR option was that it might help with accumulation of moisture, or at least resistance to down collapse once moisture accumulates, in the winter when not using a VBL. Certainly if the dew point is inside your bag and water condenses in the down, a treated down bag should do significantly better than an untreated bag.

What I wasn't sure about, and what I think Richard's chart partially answers, is whether the treatment would also suppress water vapor adsorption (from high humidity, but non-condensing) onto the down. It seems, however, that there is not a big effect on loft based upon relative humidity. That doesn't mean there is no benefit for vapor adsorption from the treatment, though – if the coating does suppress surface adsorption then it may delay formation of water droplets in the down due to lack of nucleation sites. We use hydrophobic coatings at work (think NeverWet style stuff) and in addition to reducing surface adsorption of water they also make it really hard to condense liquid on the surface. Instead of a thin film of fog (like your bathroom mirror after a shower) they will have very tiny droplets condense on them at imperfections in the coating and much less water will condense on the surface. I have absolutely zero evidence either way as to whether this happens in treated down or not, but I'm curious.

By the way, for those questioning the durability, this was addressed in this excellent video series by ProLite Gear (RIP):

Behind The Scene with DriDown

I don't have the time to find it right now, but in one of the later videos (part 3 or 4?) the guy from Sierra Designs comments that both treated and untreated down were put through the standard aging process (some large number of washing machine cycles) and the DriDown actually was more durable than the untreated down, and that they did not see evidence of the coating degrading.

[edvin mellergård]

Richard Nisley: How was the testing done in the studies you quoted? Do you have a link or the name of the studies? (I have access to most scientific databases through my school)

My own (subjective) experience is that down collapses alot more than shown in the graphs. Could it be that the testing is done with undisturbed down that just sits still in a container and in the real world the down is compressed every now and then as we move around and that makes it collapse more?

Or another explenation is that what we all experience is just water condensing inside our sleeping bags and jackets, gets sucked up by the down, and that causes the much greater collapse.

[Eric Blumensaadt]

Bob, the coldest I've ever experienced was as a Nordic ski patroller for the '79 Pre-Olympic World Cup at Lake Placid, near you. It was -40F. the last day and all Nordic events were cancelled. And it was -50 down in Keene Valley! Most cars would not start. Mine being brand new barely got running.

We patrollers wore our base layer, a Nordic ski outfit and then an insulated alpine ski outfit over that. And our XC boost were covered with foam filled overboots. We were fine, with our Frostguard or Vaseline face cream, mittens and balaclavas covering most of our faces.

When we patrolled the '80 Olympics reg next year it was so warm and nearly snowless they had to rent hunter Mountain's snow making guns, make huge piles of snow, truck it out all over the XC courses and have specially weighted groomers and track setters work on it. But, hey, it got done and we had the races.

[Bob Moulder]

@Andrew F – thanks for that link! I watched the videos and they were very informative. That shaker test was pretty rigorous with 50,000 cycles. Don't know how I managed not to get a google hit on that… perhaps all my keyword lists contained Downtek and not Dridown.

@Eric B – It is sobering to think that there are lots of people who live in such climates (and colder!) and experience these temps on a regular basis. Like anything else, humans adapt and get used to it, which is why "cold" is a subjective term.

[David Ure]

So here is another set of questions. Lets assume the treated down does what it is required to. The moisture simply beads up on the down (or absorption is minimized).

What then happens to the moisture?

Does it soak the nylon outer fabric of the sleeping bag?

If the outer fabric has a good DWR does the moisture still stay within the bag?

Does the moisture make it through the bag and again, if the fabric has a good DWR, simply bead up on the outside of the bag?

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