Rain Gear
The outermost layer in your summer clothing arsenal should always be some solidly built rain gear. I am still dumbfounded at the number of times I've seen people with a cotton sweatshirt tied around their waist blithely heading upward above timberline as a vicious squall gathers strength and begins bearing down on its clueless victims.

The least expensive rain gear is a plastic poncho, a large square of vinyl with a hole in the middle capped with a hood. Unfortunately, ponchos are only useful in brief, gentle rains not accompanied by wind – a description that doesn't fit the typical high-mountain thunderstorm. In a real thunderstorm, a poncho's loose, floppy fabric is guaranteed to billow up around your face with the first gust, leaving you blinded and stumbling while the wind-driven horizontal rain soaks everything below your shoulders. Don't waste your money on a glorified table cloth, no matter how cheap it seems; you'll want something better almost immediately.

The next step above a poncho is a rain jacket made of urethane-coated nylon. Such garments are waterproof if the seams are sealed and the coating hasn't worn away under the abrasion of your pack straps, but they allow sweat to escape only at the cuffs, neck and waist, not through the fabric itself. If you wear such non-breathable rainwear while you're inactive (fishing, swearing at fishing, swearing off fishing forever, etc.), then it performs adequately. If you're active, however, (storming back to camp after snagging five flies on the same underwater log), it's difficult to prevent sweat from building up inside your rain gear and soaking your insulating layers. When hiking hard in non-breathable rain gear, you face two ugly options: get soaked by sweat, or remove your rain gear and get soaked by rain.

This eternal dilemma has spurred the development of dozens of fabrics that claim to be both waterproof and breathable. The first was Gore-Tex. Since this is the first time this modern "miracle fabric" has surfaced in this book, it seems fitting to offer a brief explanation to those of you who haven't yet been exposed to W.L. Gore's advertising avalanche. In truth, Gore-Tex is pretty nifty stuff. By all reasonable standards, Gore-Tex is indeed impenetrable by liquid water; by most reasonable standards, in most situations, Gore-Tex does indeed breathe, allowing moisture in the form of water vapor to escape from your sweaty body. This miracle is achieved by the construction of a two-layer composite. One layer is made of expanded polytetrafluoroethylene, PTFE for short, better known as Teflon. This material is laced with nine billion pores per square inch. These pores are larger than the water molecules found in water vapor, but smaller than a droplet of liquid water. The second layer, whose name is even more unpronounceable and therefore seldom mentioned in polite society, is a non-porous film of polyalkylene oxide polyurethane-urea that absorbs water molecules on the warm, humid side of the material, next to your body, and discharges those molecules on the drier, cooler side away from your body. The Gore-Tex membrane "breathes" when the temperature and humidity on the inside of the fabric next to your body is greater than the temperature and humidity on the outside of the fabric. In most situations where you want to be wearing rain gear or other Gore-Tex garments, such conditions prevail.

Waterproof/breathable fabrics go a long way toward soothing the hiker's lament, but don't expect miracles. All waterproof/breathable fabrics have limitations. Sweat can only escape in vapor form. If it's extremely cold and your sweat condenses into liquid droplets before it reaches the inside of your jacket, the moisture will remain trapped inside your clothing. I’ve pulled off a Gore-Tex shell glove in zero degree temperatures and found the fleece liner glove inside covered with frost. My sweat was evaporating off my skin, migrating through the fleece, hitting the cold shell and condensing. In those situations, a waterproof/breathable fabric scarcely breathes at all. Sweat can also only escape if the temperature and humidity inside the garment is higher than the temperature and humidity outside. If you're working hard during a steamy Georgia thunderstorm, your rain gear probably won't seem very breathable.

For a time, manufacturers of waterproof/breathable fabrics seemed intent on waging an MVTR war, with legions of shock troops rolling out statistics on the Moisture Vapor Transport Rate of their fabrics. The MVTR is usually expressed in terms of the number of grams of moisture that can pass through a square meter of fabric in 24 hours under specified conditions of temperature and humidity. Things have gotten pretty quiet on that front lately, partly because every manufacturer had his own test, which made it impossible to compare results among different manufacturers, partly because it was hard for consumers to relate the test results to the real world and partly because Gore-Tex seemed to be winning the war and the other manufacturers decided to shut up and cut their losses.

Suffice it to say, however, that even the most breathable fabrics can only pass a certain amount of moisture per hour. If I go running during a Colorado thunderstorm, I often find upon my return that the inside of my rain jacket is damp. The jacket feels like it leaked, but when I test the fabric with a device that forces water against the fabric under pressure, I find that the material is still waterproof. It simply can't breathe fast enough to dispel the amount of moisture I produce during very vigorous exercise.

You can enhance the breathability of your rainwear during rain storms if you maintain the surface water repellency of the fabric. All rain gear comes with a water-repellent treatment applied to the outer surface of the fabric. This treatment is distinct from whatever method the manufacturer uses to make the fabric waterproof. The water-repellent treatment causes water to bead up on the jacket's surface. Once that treatment wears off, water tends to coat the jacket's surface in an even film. That coating of water chills the fabric by evaporation, which promotes condensation inside the jacket. The coating may also reduce breathability. The water repellency of your jacket can be renewed by applying various products available at specialty retailers.

Like breathability, waterproofness is a relative term. Here the statistics are usually given in terms of pounds per square inch of water pressure that the fabric will withstand. According to W.L. Gore & Associates, makers of Gore-Tex, a 165-pound man kneeling on wet ground is pushing water against the fabric of his rain pants with a force of about 16 pounds per square inch. When he's sitting, he's exerting a pressure of about three psi. The military standard for waterproofness is 25 psi. Some manufacturers give the waterproofness of their fabric in terms of the height of a column of water that the fabric will withstand ("Our fabric will withstand a column of water four meters high!"). While these numbers may sound impressive, they're actually not. A water column four meters high, for example, exerts a pressure of less than six psi. That's adequate for a ski garment exposed only to falling snow, but pretty marginal as summer rain gear, particularly when you consider that waterproofness generally declines with repeated washings.

Despite all these caveats, waterproof-breathable rain gear is still a major improvement over non-breathable gear. In my opinion, Gore-Tex is probably still the best waterproof-breathable. Its competitors are generally either less breathable, or less waterproof, or both. Gore-Tex is admittedly expensive (somebody's got to pay for all that advertising), but most hikers and backpackers seem to have decided that it's worth its cost.

Gore-Tex is used in two ways in rain gear. In three-layer construction, the Gore-Tex membrane is glued to both an inner and outer fabric. In two-layer construction, the membrane is glued to only the outer fabric; the lining fabric, which is essential to protect the membrane, hangs free. Three-layer Gore-Tex jackets are more durable but stiffer than two-layer. The breathability of the two constructions is about the same. For the most part, I prefer three-layer construction for its durability.

I used to believe that only a rain jacket was really needed, and that rain pants were an unnecessary weight and expense. Then, like the people I now decry, I foolishly pushed for the summit of 14,255-foot Longs Peak one August day a number of years ago, disregarding the approaching thunderstorm. The wind-driven horizontal rain, hail and snow immediately saturated my long johns. The evaporative cooling from my legs was so severe that no amount of dry, rain-jacket protected insulation on my torso could keep me warm. A few years later, having inadequately learned my lesson, I asked Jeff Lowe, one of America's most experienced Himalayan mountaineers, if he was going to bring rain pants when we tried a climb on Longs' formidable east face. I assumed that a tough guy like Jeff, intent on going fast and light, would eschew such frippery as rain pants. "I always bring them," he replied. I did so too, and was glad – we were hammered by a severe thunderstorm only halfway up the peak and forced to retreat. I've brought rain pants on mountain ventures ever since, whether I'm off to do a difficult climb or just take a stroll up to some beautiful lake.

You could do worse than to select your rain jacket on the basis of how well you liked the hood design. In general, I prefer integral hoods that are sewn permanently to the jacket because they're easier to pull up over your head, particularly while wearing gloves in a high wind. The alternative is a detachable hood that usually stows in a pocket in the collar. Detachable hoods only stay on your head in the wind if you fasten two flaps across your chin with Velcro or snaps, a feat that can be awkward while wearing gloves. Stuffing the hood into the pocket on the collar usually turns the collar into a cervical brace – fine if you're planning on rolling your truck in a crash on the way to the trail head, not so great for comfortable hiking.

In most situations, you'll be wearing a pack over your rain jacket. Make sure, therefore, that your pack's shoulder straps and waist belt don't cover up the pocket openings. Be sure, too, that the contents of the pockets can't drop down beneath the waist belt, where they can chafe and jab.

Next Page: Insulated Parkas

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