I’m dealing with that right now (waterproofing “dandruff”, i.e catastrophic coating delamination) with a range of my gear, from a sprayskirt and the fly for my big car camping tent (REI Hobitat) to the inflatable sponsons on two Pakboat folding kayaks.
i do recall from my days as a professional gear peddler and the manufacturer’s saleperson training seminars on the new breathable WP coatings that were coming into the market in the mid 70’s that we were taught to warn buyers about exposing GoreTex and its analogs to any sorts of chemicals, from dry cleaning fluids to bug dope and any sort of petro vapors (in other words, don’t stash your GoreTex parka in the car trunk with those leaking cans of brake fluid and oily rags.)
Even with that info drilled into me, I trashed my own favorite rain parka (not GT but an EMS brand alternative), a biking friendly design, international orange with a hood that accommodated a helmet and a long drop tail. Besides for biking and backpacking I also used it on construction sites and it had gotten grubby. Went to wash it (something I had done before without incident using mild soap and cold water on gentle cycle) BUT, without thinking, sprayed it liberally with stain-release pre-treatment to get some black greasy marks off. When I went to take it out of the washer after the rinse cycle, at least half of the white vapor barrier layer had shredded off and been captured by the mesh lining and the rest was peeling. A solvent in the pre-treat fluid had dissolved the bond between the vapor layer and the nylon taffeta shell. Totally not salvageable.
And all of the accessory components of my 2007 Feathercraft folding kayak that are made of WP coated ripstop cordura (the sea sock, custom backpack and the bungeed hatch covers) have delaminated in little checkerboards that are clearly the result of the adhesion bond breaking along the higher denier fabric reinforcing threads. These are all fabric surfaces which have never been subject to any sort of abrasion (except for me lifting a knee from beneath periodically while paddling to dump the spraydeck pooling from my GP runoff.) Other Feathercraft owners have reported the same effect. This is not typical of Cordura. I have a Wilderness Experience square Cordura duffel bag iI bought in 1977 that still has intact coating. For 45 years have stuffed wet gear and eventually all my roof rack straps, hardware and cable locks into it The bag has lived in every one of my cars since back then being subject to being kicked around and temperature changes from over 100 to sub zero.
In the case of the urethane-coated nylon in the kayak sponsons, apparently there are two distinct types of urethane compound used for waterproofing and one bonds durably with fabric and the other (cheaper) type does not and eventually fails. I knew this was the case from my tent-selling days. It was well known in the industry that the cheaper Eureka line of tents would have their floors and flies fail in waterproofness within about 3 to 5 years, depending on usage, whereas a well cared-for North Face, Sierra Designs or Trailwise tent would stay raintight for a decade or more). In fact there was a new tent company (memory fails me on name) that we picked up in the late 70’s started by former Eureka employees who copied many of the classic models but used higher grade materials, including the more durable waterproofing laminates.
Going back to the failed sponsons, apparently PakBoat’s Asian subcontractor shipped one batch of those components made with the substandard coating – the company eventually caught the defect when they started leaking air within a year and offered free replacements. But the folks I bought two of the affected boats from apparently missed that warranty call.
I only bring all this up to say I have been doing a lot of digging on vapor barrier delamination, though mostly for total waterproofing, not breathable. Breathable laminations are tricky because you have to preserve the microscopic pores that make the stuff work in transporting vapor before it condenses. So heat lamination and most glues don’t work and you can’t just re-coat “breathable” fabrics. W. L. Gore developed the machine and process for producing ePTFE (expanded Teflon) film and has patents on it, particularly the lamination processes that preserve the pores, though these have been challenged multiple times – nobody, to my knowledge, has succeeded in making an analogous breathable material that is as durable and works as well, let alone better.
In the case of your dry pants, are they the same material in the flap as on the main body of the garment? In some cases I know that coated material (cheaper) is sometimes used in portions of an item that would not benefit from being breathable because they are layered under other surfaces (you need water vapor pressure behind a microporous fabric to force the molecules through.) Could be a different material or coating, or it could just be the abrasion that part of the pants was subjected to that caused it.
I just got a shipment from Gear Aid of their “Seam Grip +TF” Tent Fabric Sealant. It’s in a sponge applicator bottle and supposed to cover 85 square feet of tent floors, flies and seams. I had set up the Hobitat in the yard a week after I got back from Michigan Qajaq camp to air and sweep it out (it was pouring the day we broke camp so it all got packed wet and sandy). I knew the seam sealant had started to peel off like old sunburn but when it dried out I realized that ALL of the waterproofing on the fly was complete dandruff. I had to soak it and wash it it a cotton sack to keep the shreds from clogging my washer motor, then shook it inside-out on a tarp to vacuum them up.
Once it is thoroughly cleaned off I will stake it out and try to re-coat it with this stuff (also will try it on the spraydeck). I am probably putting way more effort than is worth it into trying to salvage this tent (I bought it used with a bent pole for $100 ten years ago) but I really like it for space and ease of set up. And before this failure it kept me reliably dry in some really nasty conditions, like a week in Quebec where windy storms poured onto it continually from 6:00 PM to 6:00 AM every night.
I’ve never used Gear Aid’s product and will report on how well it performs.