I just finished an experiment on my Patagoina Houdini which significantly extended its waterproofness. The weight increase and breathability decrease weren’t measurable. I used McNett Silnet on the inner top seams and zipper fabric.

Water repellency- is a fabric's ability to make water "bead" and roll-off. Effective DWR is desirable in a fabric as water soaking into the outer fibers will inhibit breathability. DWR coatings can and do wear or wash-off (they can be renewed or re-activated) whereas waterproof inner coatings or membranes will to a greater or lesser degree last the lifetime of the garment. In the case of the Patagonia Houdini, the fibers are encased in silicone so the DWR doesn’t need reapplying for the life of the garment and there is no waterproof inner coating or membrane.

Waterproofness - is a fabric's ability to prevent water from passing through the fabric under force. The Nextec Epic 4 Summit Nylon has a waterproofness rating of 1.8 PSI. The Patagonia Houdini material seems to have a similar PSI rating.

Misting rain averages up to .4 PSI of force on the fabric. Drizzling rain averages up to 2.6 PSI of force on the fabric. Because of the requirement to pass 5 CFM of air, the Houdini’s pore size will only block misting rain from passing through the fabric and block heavy drizzle for an extended period before it starts to pass through. My objective was to extend the time period I could use the windshirt in heavy drizzle.

I put on a long sleeve absorbent shirt and the Houdini. I then rotated slowly in the shower until I could feel moisture pass through different areas of the windshirt. The only areas that moisture passed through were the top seams and the zipper (very heavy leakage). The arm seams and side seams never leaked because the shower head pressure didn’t reach those areas.

I used McNett seam seal on the inside top seams and all of the zipper fabric. This allowed the same extended shower time without experiencing any water pass through except for very minor leakage through the zipper teeth. The downsides are that you can easily see the inside Silnet coated seams through the shear fabric (looks like the fabric is soiled) and the Silnet seams do not feel as pleasant against bear skin as untreated cloth. I cut out the labels and so there was no increase in weight as a result of applying seam sealer (besides that the labels were a leak point).

I take multi-month expeditions to Alaska. I carry a WPB suit in addition to my windshirt. The DWR wears off my WPB suit after 30-50 miles of abrasion from the pack straps and under brush. By extending the range of use of my windshirt, I am trying to reduce the use of my WPB so as to extend its DWR.

Has anyone else done something similar to their windshirt? If so, were the results worth the effort?

Richard:

Which wp/b jacket are you wearing? I've had mine for almost three years now, and the DWR is just fine (although recognizing that we do very different kinds of hikes).

MontBell (maker of my jacket) claims that its jackets retain a full 90% of its original water repellancy even after 100 washings -- and the cumulative effect of 100 washings on any DWR is pretty compelling.

Seems a shame to carry a second shell only because the first shell isn't performing like it should...

Edited by ben2world on 03/29/2007 11:29:56 MDT.

I have sealed shoulder seams on an Epic windshirt----and one case even installed a water resistant ykk zipper. These measures really do make a huge difference, even in a thunder shower (for Epic, anyway).

By the way, speaking of packstrap abrasion, the water shedding qualities of Epic won't wear out due to abrasion but the pressure of packstraps on Epic material will eventually cause water to wick through the material.

Ben-I use a Lowe Alpine Evolution eVENT rain suit and McNett’s REVIVEX DWR.

Kevin-I am also an Epic outer wear, with supplementation, fan. For bushwhacking in wet environments like SE Alaska, Epic provides the only DWR that will last the life of the fabric. Water works through the pack straps of Epic but the rest of the surface stays dry in the drizzles. Also after the pack is taken off, the shoulder strap areas again repel water with Epic, unlike a conventional DWR on a WPB. Which Epic jacket and pants have you found to be the best for backpacking?

While doing Alaska bushwhacking, my experience has been that the DWR is quickly worn off from the front of my pants, my lower arms, and the bottom half of my jacket. By contrast, the DWR on my ski wear or city wear lasts for many years of repeated washing without wetting out. The fluorocarbon based DWRs (Grangers, REVIVEX, etc) last the longest while the wax based DWRs, such as Niwax, last only about 60% as long. My experiences have led me to the conclusion that abrasion quickly destroys DWR whereas washing in non detergent soap does not. What is the benefit of eVENT or any other membrane or coated WPB over non-breathable rain wear if the DWR is gone (wetted out)? The fabric no longer effectively breathes. There is no standard test for measuring the abrasion resistance of DWRs. This could be a very interesting BPL series of articles.

I checked two formal studies, that to varying degrees, collaborated my personal experience. Phil Gibson of Natick labs tested DWR treatments for durability by washing. He concluded that none of them lasted longer than the Armed Services proprietary Quarpel and Quarpel only lasted about 10% longer than the best commercial DWR. Leeds University tested the major European DWRs for pack strap abrasion durability. They concluded that the best available was Grangers (fluorocarbon) and it would permanently remove the DWR from the shoulder strap area after only 50 miles of hiking because of abrasion. Niwax lasted only 30 miles. Unlike Epic, when you remove your pack the shoulder strap area water repellency isn’t restored with conventional DWRs.

Edited by richard295 on 03/29/2007 15:26:19 MDT.

Richard:

As I don't hike for months on end, I'm "out of my league" here, so to speak.

I'm not too surprised that after-market spray on's or wash in's don't last very long... but I am still incredulous that the factory DWR on your Lowe Alpine should have worn off so quickly -- and pervasively!

I am now curious if this is an all-too-common problem for thru-hikers -- where their wp/b jackets are really only good for the first month or two or their trips -- and then they just wet out due to DWR deterioration after that???

Edited by ben2world on 03/29/2007 14:18:12 MDT.

Richard, thank you for the informative post. As with most your posts I saved it for future reference, and put McNett SilNet on my 'to buy' list from REI. First time my Houdini wets through I will treat it according to the process you described. Just this morning I rode my bike to the train station in a drizzle, and as you predicted, the jacket did not leak.

My experience with spray on DWRs is similar, they don't last long. Specifically, my Montbell Windblaster is a nylon windshell with DWR. After maybe 10 hours of exposure (not continuous) to pack strap abrasion, the shoulders would quickly wet through even when not wearing a pack, while the rest of the jacket remained dry. Re-applying some generic spray-on DWR returned it to moderate waterproofness.

I don't think I would buy another goretex or goretex-type DWR/PU laminate clothing item again now that we have epic, eVENT, HyVent, and Patagonia Deluge(i.e.Houdini). Strange thing is, goretex really has the market cornered here in Japan, people still think it is the best, all the hiking magazines and books recommend it, and newer fabrics languish on the clearance rack.. I bought a ladies eVENT jacket for the equivalent of $25.

Has anyone tried using a stretch Epic jacket over there Patagonia Houdini when the rain is too heavy for the Houdini.Would this be more breathable than Gore etc if the Epic jacket had core vents etc.I travel for 12 months or more and find that the standard DWR wears off too quickly and i don't carry tech wash or rivivex etc.I want something that i can just use normal soap on.Would a Wildthigs Epic windshirt work,Thanks.

Someone can correct me if I'm wrong but my thinking is that once the Epic jacket wets out, the Houdini would soon follow. Increased hydrostatic pressure caused by the Epic shirt as it contacts and slides over the surface of the Houdini would force water through the latter much quicker than if it were your only layer. Just a thought. I'm also thinking that the breathability of the Houdini might cause perspiration to become trapped between the two layers.

The fabric on the Houdini is encapsulated like the other Nextec fabrics, but is it is lighter. Patagonia doesn’t call it Epic but I believe that was purely a marketing decision. You can seam seal the zipper and top seams on a Houdini or another Epic windshirt to handle extended heavy drizzle and never need to reapply DWR. Above the level of precipitation that Epic will handle, you need something that is truly waterproof. Two Epic garments on top of one another will not solve the problem but, one Epic and one woven WPB jacket, Propore jacket, or poncho tarp will.

For long duration trips, seam sealed Epic use, for the vast majority of the time, will mitigate the lack of woven WPB DWR abrasion resistance, Propore’s fragile nature, or a wind blown poncho tarp.

Seam sealed Epic wind pants should keep you dry for on or off trail backpacking. If you anticipate sitting in water or kneeling in water, something like the Golite Reed pants or equivalent can be used in place of Epic pants.

Our Special Forces have similar requirements that long distance wilderness backpackers do. There are no facilities for replenishing the DWR in the field. They no longer use a conventional WPB hardshell. They use an Epic windshirt and windpants for the vast majority of the time. They augment the Epic with non breathable rain gear for the very infrequent times when it is needed.

Edited by richard295 on 03/30/2007 17:31:59 MDT.