High Tech Fabrics
For the Outdoors

Photo by Wart Dark, licensed under Creative Commons Attribution-Share Alike 3.0 Unported

A Guide Through the Maze of Chemistry’s Latest Miracle Fibers

The ages old problem of being miserable in cold, wet weather has been solved. At least that’s the claim made by today’s high-tech textile mills!

by Timothy P. Banse

Modern outdoors clothing is woven with fabrics that are waterproof, breathable and toasty-warm even in the most adverse conditions. If you buy and wear the right clothes, apparently, you can comfortably ignore a sleet storm. Unfortunately, this modern miracle has created a new problem of its own. We counted more than 200 fabric names during research for this article. Without carrying a computer printout, how can a person confidently walk into a store and buy the best garment for his needs? The answer lies here on this page as we are about to walk you through the jungle.

Jargon Buster:
A microporous material is a material containing pores with diameters less than 2 nm.

Buyers of outdoors clothing, and this includes everyone from hunters to campers to football season-ticket holders, are confronted with clothing racks filled with a dizzying array of tradenames like: Hydrofil, Versatech, Quallofil, Ultrex, High-Trek and dozens of others. Some fabrics come directly from chemical labs like DuPont, Allied, Amoco and 3M. Some come from fabric companies that purchase fibers and hybridize them. And still others come from clothing manufacturers that market proprietary names.

The best way to demystify this puzzle is to separate fabrics into their three basic categories:

1. Shells
2. Waterproof/breathable fabrics
3. Insulation linings

The shell is simply the outside layer that holds the garment together. It’s constructed from synthetic or natural fibers, or both. Depending on the mill, the shell may be coated or bonded with a semipermeable laminate or membrane.

No doubt the most fascinating question regarding high—tech fabric is: How can a single garment keep rainwater and wind out while allowing perspiration to escape and keeping body heat in?

The answer is as simple as the sea is salt: Waterproof/breathable fabrics are semipermeable membranes, coatings or microporous fabrics capable of differentiating between body generated vapor and outside drops of water. GORE-TEX, from W.L. Gore, probably the best known, high-tech outdoors fabric is actually a thin film with 9 billion microscopic pores per inch. Each of these pores is 20,000 times smaller than a drop of water, yet 700 times larger than a water vapor molecule. This means rain drops are too big to penetrate while vaporized perspiration is easily expelled. When Gore-Tex is bonded with an outer shell you end up with a breathable, but totally waterproof, windproof garment.

Photo by Alinja under GNU Free Documentation License, Version 1.2

Rain drops beading on a GORE-TEX jacket.

Microfine, from DuPont, is also microporous, but it isn’t a separate membrane or layer. Instead, it is a fabric that achieves water repellency and vapor breathability by way of the density of its weave.

Sympatex, which has the same characteristics as a microporous membrane, is actually a nonporous membrane.It achieves breath ability through hydrophilic chemistry, which diffuses perspiration along water attracting regions in the solid membrane. The same effect can also be achieved by certain coatings.

These differ from membranes in that they are spread in liquid form and cured on the shell. Thickness is critical. The coating must be applied as thinly as possible or the water vapor will be trapped inside. If applied too thinly, pinholes allow water droplets to migrate inward.

MicroTec, from MicoPore is a microporous coating.

Aqua-Guard from Rotofil is a nonporous coating.

Helper finishes such as Zepel are often combined with coatings to induce water to form is large droplets and more easily run off the shell.

Being wet is bad enough, but being cold and wet is insufferable. A good lining eliminates this misery by providing insulation and a degree of moisture management. Insulating fabrics slow down the natural process of air warmed by body heat from migrating outward to the cold. But high-tech textiles, such as Du-Pont’s Thermolite and 3M’s Thinsulate, not only combine high heat retention with minimal bulk, even when sopping wet.

Another kind of insulating fabric is composed of fibers that are hollow. Dead air is trapped inside and insulates while the surface area wicks perspiration away. Fabrics that fall into this category are DuPont‘s Coolmax, Thermoloft, Quallofil and Thermax.

Long underwear, the ultimate warm-weather item, should wick perspiration away from skin, transfer it to outside layers of clothing and provide insulation. To accomplish this, Duofold uses a 2-layer system combining Thermax and wool. The Thermax layer feels soft next to skin and enhances the wool layer’s natural warmth and tendency to wick moisture away.

High Tech Hiking Boots

Not too long ago hiking boots were as heavy as a pair of bricks. But not anymore. Super tough Cordura, from DuPont, now replaces leather in upper panels to reduce weight. Microporous membranes and water-wicking insulations, equally lightweight, perform their magic to keep feet warm and dry. Vibram soles, developed by the U.S. Army for humping jungle trails in Vietnam, offer good traction and seem to last forever. The result is a rugged boat weighing just 2 pounds.

Hype Versus High Tech

It‘s impossible to be familiar with every single fabric, fiber and proprietary brand name. Several new ones, in fact, seem to sprout every day. That said, there is a way to shop for high-performance clothing and find the garment you need. First read the hang tag and determine whether the waterproof/breathable component is a membrane, a polyester coating or a microporous weave. Membranes do a slightly better job managing moisture and may last longer. Coatings, on the other hand, tend to be softer and more supple. Micro porous weaves, becoming widely used, may be the wave of the future.

Next, check details of construction. Because water tends to seep in at the seams, quality garments tape shoulder seams. The best designs eliminate shoulder seams altogether. Also crucial for keeping out water are flaps behind zippers and closure cuffs.

Waterproof/breathability makes good sense if you anticipate spending extended periods in a driving rain, but may be overkill for alpine skiing where you might be better served by a waterproof shell.

Some dastardly manufacturers tend to confuse buyers by inventing proprietary names. The main thing to remember is that searching tags and labels for primary fibers is the best way to separate high tech from hype.