It is an honor and pleasure to be able to bring this comprehensive, 9,000 word primer to the BackpackingLight.com readership. Herein, Alan crafts a wonderful tale of controversy, technology, performance, practical usage guidelines, and a bit of politics in a technical literary piece destined to become a classic at BackpackingLight.com. Meet the characters who shape the evolution of waterproof breathable technologies, including Dr. Phil Gibson of the US Army Natick Lab: a materials science engineer who casts a cautious eye on manufacturers while looking at their fabric's breathability performance with a psuedo-realistic laboratory testing protocol; Dr. Liz McCullough, Director of Kansas State University's Institute for Environmental Research and proponent of merging laboratory data with real world performance; Dr. Fred Wilson, a chemical engineer of BHA Technologies and technology guru of new fabric known as eVENT that is giving Gore-Tex a run for its money; Mr. Glen Crowther, of W.L. Gore, who maintains that there are few real-world differences in the best waterproof-breathable fabrics available today (that's because Gore-Tex no longer stands at the top of the breathability test podium); and Shunichi Higashi, General Manager of Textiles for Toray America, who has quietly brought a new fabric to the table that promises to revolutionize the performance of lower-cost and lighter polyurethane-coated fabrics.
Herein, Alan takes a hard look at how various waterproof-breathability technologies work, including the PTFE-PU sandwich we all know as Gore-Tex, from its failed inception to its current XCR and PacLite III benchmarks; eVENT and its revolutionary PTFE membrane that has Gore and others watching nervously; Toray Entrant G2 XT, a microporous hydrophobic polyurethane fabric that is quietly creeping into the medal round and playing hardball with the big boys; and microporous polypropylene technologies used by Rainshield and Frogg Toggs. Find out how all this stuff works, who's got the best gig going, and what's in store for the future.
Finally, Alan masterfully crafts a set of simple usage guidelines based on the technology overview, offering sage advice for both selecting appropriate rainwear and using it properly.
So kick back, take some time, dive in, and prepare to learn. You're not going to find this kind of stuff on your local magazine stand. ARTICLE OUTLINE
- Introduction to Waterproof Breathable Membrane Technology
- How Gore-Tex Really Works (The Answer May Surprise You)
- Definition Sidebar: Breathability, Thermal Resistance, Air Permeability, Hydrophobic Microporous Membrane, Hydrophilic Monolithic Membrane
- Polyurethane Membranes (Hydrophilic Monolithic)
- Advantages of PU-Only Garments
- Advantages of eVENT Garments
- Venting a Garment
- Drawbacks of eVENT Garments
- 3M Propore: Microporous Polypropylene Laminate
- ntrant G2 XT (Hydrophobic Microporous WP/B Polyurethane)
- Laboratory Fabric Breathability Tests: Which one? Do they mean anything?
- Table 1. Results from Different Water Vapor Transmission/Resistance Tests Performed on WR/B & WP/B Shell Fabrics
- Sweating Hot Plate (SHP) Test
- Dynamic Moisture Permeation Cell (DMPC) Test
- Rain Shell Usage Guidelines
- Rain Shell Selection Guidelines