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.