When a Jacket Is "Overkill"

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There are huge differences between the water resistances of different fabrics. Breathability and durability among water resistant fabrics also varies widely, as does the quality of construction of the garment itself.

As a general rule, you get what you pay for when it comes to water resistant garments.

Low-End Fabrics: Low cost fabrics are often relatively loosely woven nylon, made water resistant with a thin coating of polyurethane or similar material on the inside. The coating mechanically blocks most water penetration, but also hinders the exit of water vapor. Translation: you might not get wet from precipitation but you'll drench yourself in sweat. Also, these thin coatings have a tendency to wear quickly at the shoulders, elbows, knees and seat.

Another way apparel makers impart water repellency to loosely woven nylon fabric (read: less expensive) is via a DWR (Durable Water Repellent) finish applied to the outside of the garment. DWRs will make water bead up and not soak in.for awhile. After hours of exposure in a steady rain, the DWR-treated fabric will eventually get wet. Also, DWR finish wears off relatively quickly in critical areas like sleeves and shoulders, so it's only a mater of time before it loses its effectiveness and a formerly water resistant jacket becomes as leaky as a sieve.

Mid-Level Fabrics: Higher-quality coated or laminated fabrics designed to be windproof, breathable, and water repellent are more robust than their flimsy and inexpensive cousins. While I've found total windproofness useful in some situations - - like trekking in dry, windy places - - the tradeoff in terms of inhibiting the escape of water vapor isn't a fair bargain.

High-Quality Fabrics: Many of the quality technical apparel makers use polyester"microfiber" fabrics to impart water repellency. With microfibers, the fabric itself presents a mechanical barrier to water penetration due to a very tight weave using small diameter threads. And, unlike nylon, polyester is inherently hydrophobic - - it and water do not get along - - which further helps keep water out.

Microfibers are quite efficient at allowing water vapor to escape, and they break the wind nicely too. An uncoated polyester microfiber shell is twice as breathable as the very best of the waterproof-breathable fabrics.

The coup de grace comes with treating the microfiber fabric with an "encapsulation DWR" that totally surrounds the fibers, unlike lesser DWRs that merely adhere to the fabric's outer surface. With encapsulation DWRs there is no coating to wear off, and the garments are not damaged by washing machines. On top of that, these fabrics maintain good breathability.

As for garment construction, look for the following: flaps that fully protect zippers and pockets from rain, a zip-in/zip-off hood, and no seams at the leak-prone shoulders. At a minimum, a jacket's venting options should include a full front zipper; "pit zips" under the arm, and vents at the chest or back are extra insurance you won't overheat and drown in your own sweat.

What you wear beneath water resistant outerwear is vital to your comfort, just as it is when wearing waterproof-breathable garments. You already know not to wear cotton, so instead wear bicomponent polyester underwear in which the face of the fabric is absorbent, and the side against your skin repels moisture. Recommended are Sierra Designs MC2, Marmot Dri Clime, Lowe Dry Flo, and TNF Micronamics. If the weather is warm, then opt for a technical T-shirt made of Cool Max, silkweight Capilene, or other wicking fabric.