BD Highline Stretch Shell “Gear of the Year” Outside Mag with GTT DWR

>> we bushwhacked uphill in the rain for three hours,
When you do this your body gets very hot, and that does two things: it drives moisture transfer outwards and it helps evaporate moisture from the surface.

Which means that they chose the most favourable conditions for testing.

Mind you, this is how modern ‘stretch’ clothing is meant to be used.

Cheers

Hi Roger,

You are correct that those two things will happen, but the question is whether the GTT DWR did not wet out, which OutdoorGearLab had observed in their TNF Summit L5 Futurelight LT jacket review (which uses TNF’s proprietary DWR), which Richard responded by highlighting the importance of DWR failure in the Futurelight thread:

It is an air permeable jacket with large pores combined with a DWR face fabric. In heavy sustained rain, the DWR will fail in a short periord of time. This will then cause three things to happen to the outside of the jacket. First the temperature will drop as much as 20F do to the latent heat of evaporation. Second, the pores will get filled with rain water. Third, the pores will stop passing water vapor. On the inside of the jacket, your persperation will condense on the cold surface; the MVTR will go to 0, and hypothermia will follow shortly.

Ask yourself why TNF didn’t test this jacket in heavy rain and publish those results?

The snewsnet.com article did not specifically mention Outside Magazine’s testing of DWR performance (maybe we’ll need to purchase the magazine to find out more details), but again, this is an initial review.

Hopefully either Richard and/or Stephen can provide some quantitative test results, complimented by BPL members and/or other reviewers subjective field experiences in the next few months. I too will try and do a short term field test and review.

If Richard and/or Stephen were to test, I suspect that their relative ranking results will match, and perhaps maybe their observations of the magnitude of delta between 2 WPB fabrics (eg. HH of ShakeDry 2x better than HH of BD.dry), despite different result values due to different test methodologies.

Cheers!

Agree.
The thing they don’t mention is the difference between how a fabric/jacket behaves when you are working hard, pumping out heat, and when you are just standing still. Very different imho.

Cheers

Hypothermia won’t necessarily ‘follow shortly’ when DWR fails.

Yes, condensation occurs inside the jacket and temperature falls in the external layer but neither of these factors will necessarily result in hypothermia. Metabolism or insulation will need to increase to accomodate this temperature fall and hypothermia is definitely more likely, but not inevitable.

This is hardly hot news, we’ve encountered this since GTX was first released.

In respect to this new jacket, all I hear is spin at this stage.  ‘I walked three hours uphill in the rain and remained dry’ is the usual non-critical bumpf we here about every jacket.

I get sweaty walking uphill in a base layer at temperatures just above freezing – adding a WPB and humidity into the equation makes claims of ‘jacket x will keep you dry’ pretty insulting to my intelligence.

I agree that a durable DWR is the secret sauce that makes a membrane jacket actually useful instead of just better than nothing.

12.5 oz

Hi Sean

I agree that a durable DWR is the secret sauce that makes a membrane jacket actually useful instead of just better than nothing.

I agree with you too, and what is so promising about GTT EMPEL DWR treatment is that based on Bundesmann ISO 9865 water repellent testing, it shows remarkable results:

GTT EMPEL DWR on 60/40 Blended Cotton/Poly Knit Fabric
https://www.youtube.com/watch?v=hjTRzt16qfs

GTT EMPEL DWR vs C0 DWR vs C6 DWR treated Cotton 10 minute comparison test
https://www.youtube.com/watch?v=F15u8TRmc8o

GTT EMPEL DWR vs C0 DWR vs C6 DWR on polyester after 5x washes
https://www.youtube.com/watch?v=09jJRsX_LaI

There are a lot more Bundesmann ISO 9865 tests on this YouTube channel, but it should be noted that the location shown in the videos is Rio Rancho, which is the same location where Green Theme Technologies Inc. (GTT) is based.

https://greenthemetek.com/technology/

Yes interesting tests but performance in extended rain and with abrasion would be required to examine performance for a WPB, I reckon.

The tests you have linked to suggest better windshell performance (as in resistance to wetting out not wind resistance)  but it is possible that there is bias as the tester and manufacturer could be one and the same.

That said, I have an open mind and a DWR that is actually durable, and non-toxic, would be a step forwards for outdoor clothing.

I have tested DWR on cotton fabric. It lasts no time at all, as the scrub damages the underlying cotton fibres at high speed. The coating just vanishes. The techie for the vendor agreed with my assessment.

Cheers

I have tested DWR on cotton fabric. It lasts no time at all, as the scrub damages the underlying cotton fibres at high speed. The coating just vanishes. The techie for the vendor agreed with my assessment.

Hi Roger,

Is the DWR on cotton fabric that you are referring to, is it the C0, C6, C8 or GTT EMPEL DWR?

This happened quite a few years ago. I think (think) it was actually EPIC fabric. They had sent me two samples of cotton and two samples of nylon. The latter made a good breathable jacket for ski touring: it kept the snow off but let the sweat out.

I made a windshirt out of one of the cottons and tried it out on a rather wet day walk, off-track through light scrub. After about half an hour the fabric wetted out completely (and I got wet). Later testing at home confirmed that the surface no longer had any water repellency at all.

Cheers

Re: “Hypothermia won’t necessarily ‘follow shortly’ when DWR fails.”

For years, I did the Maine AT in sections, using a canoe or kayak to get back to my starting point.  On some trips, it rained for days.  Saw folks in late stages of hypothermia on the trail, but experienced it myself only when kayaking the large lakes, wearing a WPB shell and using a custom built spray skirt.  So, stayed dry below the waist, except when hauling the boat over some long and sometimes deep in the water portages.

So the days on the water often included portaging where needed.  Often used a Beans GTX jacket, but there were some other WPBs, and for some nutty reason, still have some of them. Sometimes, the shells wetted out after long days on the water in the pounding rain and winds that cut the boat down to a crawl.  At that point, it was a close shave to get to shore, get the tent up, change clothes, heat and eat some food and get in the sleeping bag, all as quickly as possible.  I had seen the folks with hypothermia on the trail, and saw how they suffered delirium and unconsciousness, even after being put into a sleeping bag or bags in a shelter.

So while I don’t necessarily understand every point of Richard’s scientific explanation, I know how near hypothermia can be when shells wet out; that is, no longer have functioning DWR.  The kids I saw who did not appreciate this were from a college outing club, but at the time, trip leaders did not carry cell or sat phones. These were trips in the three seasons from May to no later than October, by the way.

Hypothermia is a killer, and every responsible trekker must know how to combat it.

All of which is why I wear a silnylon poncho instead of a psuedo jacket. The silnylon IS sufficiently waterproof, and I get a nice warm fug inside as well.

Cheers