Warm, Layered Look Makes Scientific Sense

High-tech underwear may not appear to be any more glamorous than grandpa’s long johns, but there’s a major difference, say textile technologists at the Polypropylene Council of America.

Although layering clothes for the cold isn’t a new idea, it helps to know which layer serves which purpose in the process. Fabrics of new-generation man-made fibers are engineered to perform specific functions in keeping you drier and warmer, the council points out.

There are three basic layers to a cold-weather clothing system: the vapor-transmission layer (sometimes referred to as the “wicking” layer), the insulating layer and the protective layer.

The vapor-transmission underwear layer is most important, now as always. The news is in fabric of polypropylene, a most effective fiber for transporting moisture away from the skin and for preventing heat loss when you’re active in cold weather.

Polypropylene actually can’t absorb moisture. It transmits vapor from the skin, keeping a dry layer next to you.

The next layer is for insulation; that is, to keep a space of still air around your body and to absorb the wetness being thrown off by the first layer. Many of the new fabrics are designed for this layer, and old reliable wool is often used.

You may pile as many sweaters, jackets and tops as you need into this insulating segment of the clothing system--knit shirts topped by woven wool shirts, topped by a parka, for example, to prepare you for the final shield in really wet, brutal weather.

The outer layer should be chosen to protect you from the elements. It should be water repellent and comparatively impervious to winds. The important factor is that its outer shell be breathable and water resistant, which is the way many of the new breathable membranes laminated to tough outer layers of fabric provide protection without sacrificing comfort.

These fibers and fabrics are marketed under a number of trade names, and manufacturers prominently display tags that identify the fiber content, benefits and care instructions.