It’s simple. Rain gear should keep you dry. The best rain gear keeps water out while allowing moisture on the inside (read: your sweat) to escape. The former is straightforward. The latter is often difficult to nearly impossible, a fact obscured by the marketing hype that surrounds many waterproof-breathable materials. Understanding both features is essential to selecting—and having realistic expectations for—your rain gear…
BARRIER TO ENTRY
Rain gear must feature a barrier that is impenetrable to liquid water. These barriers come in two primary forms: laminates and coatings. A laminate is a thin sheet of material glued to the inside of the jacket’s outer layer. GORE-TEX and eVent are the best-known examples, though many manufacturers offer other proprietary versions. Durable and effective, laminates easily last for years but are relatively expensive compared to coatings (laminate jackets generally run $200 and up).
A coating is a thin layer that is essentially painted on the inside of the jacket. (Marmot’s PreCip and The North Face’s HyVent are common examples.) Coatings are typically lightweight and more affordable (jackets run roughly $100 to $200), but less durable—they can rub off in high-wear areas with regular use. As a general rule, laminates and coatings are equally waterproof, though they vary in their breathability.
Durable water repellency, or DWR, is a chemical treatment applied to rain gear that causes water to bead up and roll off without penetrating the fabric. Its effectiveness has implications for breathability, but contrary to appearances, DWR does not make rain gear any more or less waterproof. DWR wears off with use; it can be reapplied using after-market products but never regains its original effectiveness.
BREATHABLE? DON’T BELIEVE THE HYPE
A lot of rain gear features a waterproof-breathable laminate or coating, which allows water vapor to escape from the inside. Despite the marketing hype, however, even the most breathable materials fail to work well in practice. Why? First, in order for water vapor to exit, the fabric must remain essentially dry (hence the value of an effective DWR coating). No water vapor can pass through saturated fabric, so breathability becomes effectively nil once rain gear is soaked. Second, even under optimum conditions, the most breathable waterproof materials can’t come close to transferring all the sweat you produce during moderate to heavy exertion.
All that being said, waterproof-breathable materials do allow some water vapor to escape, especially in cool to cold conditions when a strong temperature gradient between the inside and outside of your jacket helps drive moisture outward. As a general rule, laminates are more breathable than coatings—and even limited breathability is preferable to none. But ultimately, good venting options offer the most effective ways to stay dry on the inside. Jackets with zippers under the armpits (“pit zips”) provide good ventilation and you can also loosen the waist and open the collar as conditions allow.
For maximum protection and comfort, a good rain jacket should fit easily over multiple layers without constricting motion. The sleeves should not pull away from your wrists when you extend your arms and the cuffs should seal tightly to prevent water from leaking in. The waist should extend below your lower back and the hood should tighten snugly and move with you as you turn your head. For rain pants, the most important feature is the ability to easily slip them on and off while wearing bulky footwear. Stay dry out there!