In search of the perfect fake fabric.

In the 1980s, the spectrum of fabric quality ran from beloved natural fibers down to mediocre cotton-poly blends, then dipped into trashiness with pure polyester. Today polyester fleece is the uniform of hikers, climbers, backpackers, college kids, and people who want to look like them. As in the '70s, you're nothing in the '90s if you're not in polyester--preferably polyester from Patagonia, The North Face, Marmot, REI, or L.L. Bean.

Don't write this off as a mere fashion fad. Polyester is undergoing a renaissance because fleece is truly a miracle fabric: It's warm and durable but lightweight, and it dries faster than natural fibers. At the same time, it feels natural to the touch, not scratchy like the poly of yore. And while fleece takes over the sweater and sweat shirt market, other synthetic fabrics are horning in on the long underwear business, with equally good reason. Polypropylene and other newer polyester blends beat out cotton for keeping your skin dry and warm. In short, in high performance clothing, fake is great.

Fleece is a 100 percent polyester fabric that's made like terry cloth. First a machine knits the fleece, leaving tiny loops on its surface, then the fabric is treated in three ways. 1) Napping: Machines smack the fleece with tiny wires that break the loops. 2) Combing: The strands of fleece are groomed to stand up crew cut straight, thereby creating air-trapping space. The trapped air creates warmth. 3) Shearing: The upright strands are shorn to a uniform height, which stops the strands from getting tangled up like dreadlocks, a problem that leads to pilling.

All this manufacturing goes on not at Patagonia or The North Face or any of their competitors--these companies just design and sew the garments. The fleece used in high end outdoor clothing is made by two textile firms: Malden Mills and Dyersburg, the Coke and Pepsi of fleece. Malden Mills holds a near monopoly on high performance fleece (to find out why it's a monopoly you can love, click), while Dyersburg feasts on the leftovers. By all accounts, both mills produce superb fabric.

So, is all fleece basically the same? It is if you're the kind of shopper who only buys premium brands. Otherwise you have to contend with cheap Asian imports. People I talked to at Malden and Dyersburg complained mightily about shoddy Asian fleece flooding the market and undercutting them. In this case, there's a good reason to buy American: Most Asian fleece has been napped, but it hasn't been combed or sheared. Thus 1) Its subpar air trapping begets a pitiful warmth-to-weight ratio; and 2) it tends to pill. Some Asian fleece will even pill--horrors!--before it leaves the sales rack! (You can test this by rubbing the fleece with your palm.) To be fair, the Americans admit that Asian fleece has made great strides, but the West is still best.

Asian fleece is mostly relegated to down-market brands--the name "Kmart" was floated by one Malden spokeswoman. The top brands proudly announce that they use Malden (trademark: Polartec 100, 200, or 300) or Dyersburg (trademark: E.C.O. or Dyertech). All except for Patagonia, that is, which pretends its Synchilla fleece is something else. Despite costing more and supposedly being better, Patagonia's fleece is from Malden and Dyersburg, just like everyone else's. If there's some other difference between them, I don't know about it, because despite many phone calls and e-mails, Patagonia refused to answer my questions on this point.

Why not buy the cheapest gear you can find that uses American fleece? Because design makes a difference. Compare Campmor's $60 Polartec 300 jacket with The North Face's $160 Denali jacket, also featuring Polartec 300. Both use the same fabric, Malden's excellent heaviest weight fleece. There are three good reasons to pay $100 more for the Denali, and one so-so one: 1) The Denali has a nylon shell over its torso, improving wind resistance. 2) The Denali has more pockets, with zipper closures. 3) The Denali has flaps behind the zippers in its armpit vents (all high-tech jackets have zippered armpit vents), while the Campmor has no flaps, so cold seeps through. 4) The cool North Face logo and jacket cut will impress your gearhead friends more than the budget Campmor logo and cut.

To test the designs of these and two other popular fleece tops, I went to Duke University's zoology department, where many walk-in refrigerators and freezers are to be found. The entrants in my little competition were the Campmor, the North Face, the Marmot E.C.O. vest ($89, fleece made by Dyersburg from recycled plastic soda bottles), and the Patagonia Synchilla Snap-T ($86, the it-fleece of the prep-school, Phish-fan set).

Duke's walk-in fridge runs a cool 40 degrees Fahrenheit. With a long sleeve, polypropylene T-shirt as a base layer (more on that later), I wore each fleece in the fridge for about 10 minutes. The Marmot vest performed best, keeping my torso toasty but, of course, leaving my arms quite cold. The other fleeces would have been plenty warm during exercise, but standing still I felt a bit chilly. The North Face did a fine job here, while the Campmor faced the aforementioned armpit zipper problem. The Patagonia had two drawbacks: While in calm conditions the Snap-T was the warmest of the entrants, it was especially nonwind-resistant (the fridge had a fan). That was in part because it had no nylon lining, but it was still less wind-resistant than other competitors without a lining. Also, the Patagonia had no pockets for my hands--a shocking oversight.

Next, I ventured into the freezer, a chilling minus 8 degrees Fahrenheit. None of the fleeces came close to weathering this kind of cold. An outer layer is clearly necessary in these conditions, even when you're vigorously exercising (which I tried to do in the freezer until I quickly became lightheaded from the icy air).