Dale Evans: "Roy, what are BVDs?"

Roy: "Oh, just something us menfolks know about."

-- The Roy Rogers Show, c. 1955

Roy certainly wouldn't like us discussing it here in front of the ladies, but there's a revolution going on in long underwear that affects everyone from GIs standing watch in Reykjavik, Iceland, to glamor guys carving S-turns on the slopes at Aspen.

It turns out that synthetic fibers aren't just for bowling shirts. Polypropylene underwear, polyester pile vests, jackets and sweaters, and outer shells treated with polytetrafluorethylenes (PTFE) like Gore-Tex are changing the way Americans handle cold weather.

The northeaster that blew in over Halloween should have warned you that winter is coming. Now you'd better make sure all components of your layered, cold-weather clothing system are in place and operational.

That means a suit of polypropylene long johns to absorb moisture from your body, should you perspire while exercising in the cold; a variety of polyester pile garments with plenty of loft in the pile to trap body warmth and keep you toasty, and a PTFE-treated outer shell to block rain and wind but still breathe adequately to allow damp body vapors to escape.

Just how good are these systems? Peter Gilson at Gore-Tex, the giant granddaddy of PTFE producers, says the Army and Marine Corps liked them well enough to rewrite their ancient specifications for extended-cold-weather uniforms last month, shifting from natural fibers to four layers of synthetics and in the process reducing average total uniform weight by about 23 pounds and bulk by about half.

But Gilson has a vested interest, if you'll pardon the pun. How about responses from nonaffiliated outdoors types?

John Page Williams of the Chesapeake Bay Foundation on polyester pile: "I've done everything from work in it to sleep in it, and it's never been in the dryer yet. I just throw it on a chair and leave it for a half-hour to dry."

International yachtsman Gary Jobson on polypropylene: During a bitter cold, wet race off England, "our foul-weather gear was soaked inside and out," he wrote recently. "Cotton when wet never dries, but if our polypropylene jackets and pants were wet when you went in your bunk, by the time you woke up, they were dry."

Arctic canoeist John Lentz on polyester pile: "I love the stuff. One time I was freezing. I reached into my pack for my pile vest, and my hand felt warm the instant I found it."

These are some representative comments from rugged outdoors types who use the new synthetics, which have been available for less than a decade after being developed for Scandinavian commercial fishermen.

Many other hunters, anglers, hikers, campers and the like professed a reluctance to try the new materials. They're sticking to their old woollies on grounds that when you go out in survival conditions, you shouldn't experiment.

That's a reasonable attitude, but my limited experience with polypropylene and polyester suggests that time will prove them significant advancements on natural fibers.

Duck hunting last month, for example, I went too deep in the water for my chest waders and took a minor bath. Had I worn my old wool and cotton Duofold long johns, I'd have been wet and miserable all day. The polypropylene, which retains only one to five percent of its weight in water, dried out in minutes.

Practically everyone you ask has something good to say about polypropylene underwear and polyester pile garments. But reactions are mixed on the subject of "breathable" outerwear treated with PTFE, which is expensive and apparently works better in certain applications than others.

Turkey hunter Jim Clay said he finds Gore-Tex-treated jackets too hot for the kind of tramping through the woods he does. "I honestly don't think they breathe like they're supposed to." Fisherman Bill Brener bought a $130 PTFE-treated rain suit for his son, who reported that it was no more or less comfortable to run in than the $30 waterproof suit he'd had before.

But others swear by Gore-Tex and its PTFE kin. They say a Gore-Tex jacket serves a double function as an outergarment that breathes in fair weather and stops rain in foul. "It means one less garment I have to own and carry," said Dudley Parr, a paddler and hiker who sells outdoors gear at Appalachian Outfitters.

(PTFE, by the way, is a thin film of plastic that is applied to any standard outerwear fabric. The film is perforated with nine billion tiny holes per square inch, the holes being big enough to let vapor out but not big enough to let water in.)

Parr said PTFE has been improved since its invention in the 1970s, when it had problems with leaking. He also pointed out that polypropylene and polyester pile are not without problems.

You must be careful washing and drying both polypropylene and polyester pile garments, because at 120 degrees, they melt. "Put 'em in the dryer," said Parr, "and they're history."

Gilson, the Gore-Tex man, said polypropylene doesn't hold dye well, either, which has led his company and others to seek ways to improve the product. He said Gore-Tex has a new material coming out next year that is "both hydrophilic (absorbs water) and hydrophobic (repels water)." That means it will absorb moisture from the body, then suck it up on the outside of the garment and transfer it to the next garment for transfer to the atmosphere. To work properly, this material must be integrated with compatible garments in a cold-weather component outfit.

Many more improvements like that and you'll need a college degree just to put your underwear on, especially in the dark.

Oops. Sorry, Dale. Forgot you were here.