Downtek

[Chris B]

Hello. I am about to order a quilt from Enlightened Equipment. I am unsure if I should go with regular down or downtek. Is it worth the 20 bucks? Does anyone have opinions on downtek in a quilt or just in general?

[Owen McMurrey]

My own experience is limited to a relative few occasions where I think it made a noticeable difference vs. the untreated down sleeping bags I own. It's actually been used in worse conditions than either of them have, and performed better than they did in less challenging ones, though. I'm very happy with that, and pro treated down as a result.
What surprises me is that we don't see more feedback, good or bad, since it's been out for so long. I'm hardly on the cutting edge of gear advancements, and have been using a quilt with HyperDry 850 for 13 months.
Stuff's great as far as I'm concerned, but so far the proponents of treated down have little to add here as far as real world performance, while the naysayers have no experience with it, and aren't likely to get any.

[J-L]

Here is a quote from Will Rietveld's 2015 OR coverage:

"While at the Crux booth I had the opportunity to discuss the pros and cons of water-resistant down treatments with Crux founder Carol McDermott, who I greatly respect. Crux doesn’t use any water-repellent treatments on their down. Carol’s philosophy goes like this: Regardless of any water-repellency treatments, as has always been the case, you want to minimize any moisture from residing in your down. The reason is very simple: water is a great conductor and draws heat away from your body, negating the value of insulation. A simple analogy is this: after hiking all day, your feet get cold in the evening because of a very small amount of water absorbed in your socks, so you need to change into dry socks to keep your feet warm. A very small amount of moisture in the socks is responsible for cold feet. The same is true for moisture inside a sleeping bag or jacket; it’s best to air it out every day to eliminate moisture and retain its full insulative value. So, does water-repellent down keep you warm even if there is water inside the garment? Well, yes, if you generate enough heat to warm the water, like hiking with damp socks."

http://gossamergear.com/wp/gear-love/winter-2015-outdoor-retailer-trade-show-gear-interest-lightweight-backpackers-new-technologies-new-products

[Miles Spathelf]

I fear I don't really understand the argument from Crux's founder. I don't know anyone that is advocating getting a DWR, or not DWR, down wet. Maybe they are arguing from the "if it ain't broke don't fix it" philosophy?

[Jerry Adams]

Too lazy to reproduce calculation, but

If you weigh the sleeping bag/garment when it's dry, and when it's damp, you can determine the weight of the water.

Knowing the density of water, you can determine the volume.

The volume of water is a very small percentage of the volume of the garment.

You can use the thermal conductivity of air and water, and calculate the thermal conductivity of the combination.

Bottom line – the increased conductiviy of water is insignificant

What is significant, is when you have water in your garment, your body heat will evaporate it, and that cools you off. Probably doesn't matter if it's treated down.

Another possibility, is that when it's damp, the loft will decrease. Treated down might be better.

This is complicated and intuition may lead you astray

[Manfred]

Chris,

We used three EE Enigma quilts filled with DownTek during our Alaska Trip last summer.

We also brought down jackets that are filled with untreated down. We kept our down garments at all times dry. Over the length of our trip I noticed that my WM down jacket's loft shrunk as it got damp and there was no opportunity to dry it completely out. The quilt with DownTek didn't have that problem. This is only one observation based on a four week trip across the Brooks Range in Alaska. It is by no means scientific, nor does it prove anything. But based on that observation I'm willing to spend the extra $20 for future purchases.

Best Regards,

Manfred

[Andrew F]

I've also had a few personal experiences, not scientific by any means, where a treated down garment performed better in a wet situation than I'm used to with standard untreated down. But they definitely weren't quantitative comparisons. I think the risk in buying treated down is that somehow we discover in a few years that some aspect of the treatment is inferior (e.g. total lifetime of the down is shorter, or maybe the coating goes away quickly, or …) But as of right now, there isn't much evidence to point to any of those possible outcomes. I have two expensive sleeping bags with treated down, so I was willing to take the risk.

Jerry – that's a great idea for a test for resistance to absorbing water vapor (as opposed to liquid water testing which has been shown extensively). An ounce of treated down and an ounce of untreated down, condition both, flow 100% humidity air through them for awhile, and measure the change in weight. I wonder if Richard has any kind of apparatus capable of doing this? A simple way to do this would be to put them in a cylinder with a cheesecloth or mesh bottom and put them over a pot of boiling water, weigh both samples before and after.

[Jerry Adams]

or, take two test samples with nylon shell material on both sides and down in baffles inside. Subject to humid environment for a period of time. Weigh before and after. Measure loft before and after. Apply the amount of heat a body would generate. Measure the temperature difference across…

[Greg Mihalik]

"Too lazy to reproduce calculation, but …"

All of that post has merit. But the down, shell, baffles, and zipper can all absorb water, so it doesn't tell you anything about the efficacy of Downtek.

[Gary Tingey]

There is a great video http://vimeo.com/34761492 about how it works. I spent the extra money for it.

[Woubeir (from Europe)]

Well, I have used clothing and sleeping bags with untreated down for a long time and never noticed lower loft, even if it had been used for weeks, and since I also never got them wet enough, I personally wouldn't see the point in purposely getting something with treated down. But that's for me. Your MMMV.

[Richard Nisley]

People frequently post on the BPL forums about down COLLAPSE; I found 933 hits. Relative humidity (RH) alone (not dew point water accumulation) can only cause about a 10% reduction in down loft from its IDFL loft rating or EN 13537 warmth rating. 65% RH is the standard lab conditioning requirement for either IDFL loft measurement or EN13537 temperature ratings.

A common lexical definition of the term –collapse- is, “fall down or in; give way”. In the least, it is disingenuous to use that term for down and RH.

If I said “my random sampling of two different vendors DWR down garments showed significantly lower insulation values than comparable non-DWR down garments”, would I be disingenuous? No, but if I said DWR down's insulation value was collapsed compared to standard down, then yes.

[Miles Spathelf]

Do you happen to live in a low humidity environment? Just curious as here in the Pacific NW and Alaska things can get quite humid and I've noticed down vest/jackets have less loft in those conditions. Granted I've been using higher fp down (800s) and it might be less noticeable on lower fp products (600s)

I haven't seen any evidence that the DWR treatments on down do anything to degrade it…except perhaps to remove natural oils. But those oils are often removed through the cleaning process anyway…

Maybe someone can speak to the longevity of DWR treated fabrics (nylon, poly, wool?) and loss of longevity or abrasion resistance? I can't think of anything else to get an inkling as to long term effects of dwr treatments other than fabrics.

[Woubeir (from Europe)]

"Do you happen to live in a low humidity environment?"
I/we used the bags and clothing at a lot of places.

"Granted I've been using higher fp down (800s) and it might be less noticeable on lower fp products (600s) "
FP is 800 to 850 for both the SB's and the clothing.

[Richard Nisley]

A much older research source but the same conclusion:

You also need to be aware that as soon as you use that bag or quilt sitting in 100% RH you will cause a temperature gradient. It will range from 95F on the inside to ambient on the outside. As temperature goes up, RH goes down. So RH will decrease and loft will increase nearer to your body.

PS: Thanks Jerry A. for correcting the last sentence.

[Miles Spathelf]

Mind sharing the makers of your products? Maybe they did a great job with overfill? My experience is with Marmot vests and jackets. They are wonderfully puffy in most conditions but when the humidity is so high that any slightly colder object is covered in a mist they do loose some loft.

[Woubeir (from Europe)]

Valandré and WM.

[Jerry Adams]

Interesting data Richard

"The RH, and hence the loft, of the bag / quilt nearer to your body will increase."

I assume you mean the RH will decrease and loft will increase nearer to your body?

[James holden]

richard …

whats the ratio of down/feathers in that chart?

is it still applicable to the modern 900+ fill down we have now

personally i find a noticeable degredation in the "warmth" of high fill powered down when its very humid

rab actually makes its expedition down suit with lower fill power down in the legs because they claim its more resistant to moisture

https://www.adventurepeaks.com/shop/rab-expedition-down-suit/

the prolite folks talk about it here …

https://www.youtube.com/watch?v=J584AqcikSM

did they do these test all wrong i wonder …

Ryan Jordan
( ryan – BPL STAFF – M)

Locale:
Greater Yellowstone

NEW Re: Re: Re: Introduction to Outdoor Retailer Summer Market 2008 on 08/10/2008 08:04:56 MDT

Bill et al.,

I spoke at length with IDFL yesterday about down testing.

None of their tests stimulate real world testing. 900 fp in a test is going to be a pipe dream in the field, because they steam wash and dry the down to nearly zero humidity before doing the test. Ironically, this most recent iteration of test methods was designed to determine the maximum possible fill power for down rather than what it will look like in the field.

Interestingly as a side note, we did some 900 fp testing of down a few years ago on two manufacturer's 900 bags. We cut the bags open and sent them to IDFL. Neither made the claimed 900 spec (they tested 830-870 using the steam method). What was more dramatic was that when each down (which clearly came from different sources as evidenced by visual inspection) was subjected to 50% humidity, the differences were pretty dramatic. One bag tested at 770 fp, the other at 680 fp. It seems that at least these two sources of 900 down had feathers in it that were not resilient in response to humidity.

The kicker is that we ran the same test next to down taken from a manufacturer's 750 fp bag. at 50% humidity, the fp was 720. Why? It had more feathers that were stiff enough to preserve the loft in moist conditions.

the big question … is … is that loss lower for lower fill power down with a higher feather content …

;)

[Eric Blumensaadt]

OK Carol, time to go back to physics class.

Sure, the moisture from mostly perspiration is going to permeate the down without a good VBL suit. BUT with untreated down the moisture will begin to make the down lose loft and even MORE warmth is lost.

With DWR treated down the moisture is there but, like synthetics, the loft remains virtually the same, preserving most of the insulating value.

And the there's the drying time of DWR treated down. It's MUCH faster than regular down.

I've hiked hard with my EB Down Tech 1st Ascent vest under my eVent parka and a 30 lb. training pack. Result? Loft was maintained even though there was visible moisture on the outside back of the vest after one hour of hiking in a 45 F. drizzle.

I'm liking DRW treated down – so far.

[Richard Nisley]

Eric,

The first chart was from research conducted in 2007. They used the down purity they could extract (~850). That was the only one that I originally planned on posting.

The second report was much older and they also used the highest down they could extract (~650).

Are there any peer reviewed scientific sources you can reference to support the contrary position?

You don't need to be a scientist, just do a search using "Google Scholar" or any other search engine; next, post any credible link refuting the information I provided.

[James holden]

absolutely none as im not a scientist

we simply have the tests that our dead leader claims to have had conducted … which by the way you supplied the original post for a few years ago

one wonders about the exact tests

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=39920

and also the marketing spiel from some of the companies claiming your usual stuff

In an 80% relative humidity environment, an untreated 15-degree down sleeping bag loses up to 30% of its loft over a period of eight hours. A 30% loss of loft essentially turns a 15-degree sleeping bag into a 30-degree sleeping bag. DriDown™ sleeping bags avoid this loss of thermal efficiency by retaining 98% of their loft, keeping you warmer all night long on both short and extended trips into the backcountry.

http://www.kelty.com/dridown.aspx

and tales from various BPLers of down not lofting or feeling "less warm" in high humidity … for instance theres no way that a thermal pro fleece should feel warmer than a MB exl according to your charts … yet on cloudy overcast humid days i find this almost always the case

a quick question … were those charts conducted using the current steam conditioning method

and do you have the exact procedures for the current IDFL steam conditioning method?

heres all i could find

Steam Conditioning is the only accurate method to determine the original Fill Power. This test should be
done to verify the Fill Power of bulk down purchased from the factory.

Evaluating “usable” Fill Power is more complicated. The following information should be considered when
evaluating the conditioning methods:

 Both the Tumble Dry and Steam methods add moisture and heat to the down and feathers.

 Several thousand test results have since proven that Steam conditioning does NOT falsely inflate
the Fill Power beyond its natural, original structural value.

 The steaming process “adds” moisture and heat to the down during steaming. The down is
immediately revived with warm, dry air. (humidity?) This process simulates the factory washing process of
bulk down and the consumer washing of finished down products.

 The Tumble Dry process also “adds” moisture and heat to the down during the tumbling with a
damp cloth. The down is moderately “steamed” and revived as the cloth is dried.

 The steam method revives to a steady state as early as 24 hours after conditioning. (IDFL
recommends that Steam Fill Power always be tested after 72 hours). The Tumble Dry method
requires 72 hours to revive to a steady state.

 The Tumble Dry method can be manipulated by handling of products before shipping to the test lab.

 The Steam method gives similar results regardless of the handling of the product before arrival at
the test laboratory.

my understanding is that the IDFL tests are designed to reproduce the fill numbers as they would come straight off the production line, and to minimize the effects of shipping, etc …

they werent i suspect to see what fill power would be in the field outdoors … we dont have steam, tumble dry machines, in camp …. and it tends not to bea constant 21C at 65% humidity when we need down jackets

;)

[David Ure]

"dead leader"

Mental note: Don't be in the midst of drinking orange juice when reading Eric's posts, lest you spray said Orange Juice out your nose whilst laughing.

Seriously funny.

[J-L]

I wonder how much of the perceived performance of DWR down is psychological.

If you bought a sleeping bag supposedly filled with DWR down, but it was actually filled with normal down, do you think you would notice?

I would guess that whatever (if any) advantages DWR down has, that those advantages would deteriorate pretty quickly after stuffing and unstuffing the item many times (friction and deformation eroding the DWR coating) and being exposed to body oils that degrade normal down.

[David Ure]

"I would guess that whatever (if any) advantages DWR down has, that those advantages would deteriorate pretty quickly after stuffing and unstuffing the item many times (friction and deformation eroding the DWR coating) and being exposed to body oils that degrade normal down."

Sources please.

[Author]

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