DOWN VS. SYNTHETIC: WINNER IS A SLEEPER.

Byline: Jeff Everist Albuquerque Tribune

There's a question that has puzzled backpackers and campers for a couple of decades now, and today we're going to answer it, once and for all:

Which is the better filling for a sleeping bag - feathers or fibers, down or synthetic insulation?

Here are the arguments.

We'll start with down, since it's been around the longest.

Actually, down and feathers are two different things. Feathers have a central shaft with barbules radiating from it; down plumules grow in soft, little tufts all over a bird's skin, underneath its feathers.

A bird uses its feathers for flying; its down keeps it warm. It keeps people warm, too. We have been stuffing our beds and clothing with down and feathers for centuries.

Down has to be kept clean and dry or it will lose its insulating ability, but if you are willing to take care of it, a down-filled sleeping bag will last virtually forever.

All down is rated by the amount of volume an ounce of it will fill. That's called its fill power. The industry standard for sleeping bags is 550 fill power down - that is, an ounce sample of down will fluff up to occupy 550 cubic inches.

Ounce for ounce, 550 and better down creates more dead air space - and therefore more warmth - around your body than any other material. Also, down drapes over you, eliminating cold, drafty areas, better than any synthetic.

And nothing returns your warmth quite as quickly as down. When you slide shivering into a down bag, it's like snuggling in your mother's arms.

So, the bottom line is, if you buy a good-quality down sleeping bag and keep it clean and dry, it will provide the most warmth for the least weight, with the highest-comfort level and at the lowest cost per length of service of any bag, period.

Here's the case for synthetics.

There are several variations on the polyester theme being used in sleeping bags - Polarguard, Thinsulate, Hollofil, Quallofil, Primaloft, Microloft and Lamilite among them - but by and large, all synthetics tend to have the same disappointing traits.

A down-filled bag that will protect to 20 degrees Fahrenheit will weigh right around two pounds, more or less, depending on the quality of the down. A synthetic bag of the same temperature rating will weigh at least three pounds and perhaps as much as 3 pounds, 12 ounces.

Besides being heavier, synthetic bags are bulkier than their down counterparts. If you carry an internal frame pack, that means less room for everything else. Also, where a well-cared-for down bag will likely outlive its owner's desire to backpack, synthetic bags lose a little loft every year, no matter how well you care for them.

Synthetic fills don't drape as well as down, nor do they warm up as quickly. It's beginning to sound as if the choice between down and synthetics is clear, isn't it?

But then, I've been leading you ``down'' the garden path. Again, down will keep you warm only if you keep it clean and dry. Trouble is, down soaks up body oils, and it acts like a magnet on grit and grime. In high humidity, down will absorb water right out of the air.

Yes, there are waterproof stuff sacks and Gore-Tex shells and other ways to keep down from getting wet, but not one of them is foolproof or catastrophe-proof.

Therefore, if you can own just one sleeping bag, it ought to be a good-quality synthetic-filled one. You can trust it to keep you warm, even if it gets wet.

It may not have the life span of a down bag, but it will cost less and you won't need to be nearly as fussy about keeping it clean. The newest synthetics are only steps behind down in performance and weight, and the technology improves yearly. Besides, who wants to be stuck with the same sleeping bag for the rest of his or her life?

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Photo: Polyester-filled sleeping bags, while heavier and bulkier than their down-filled counterparts, keep campers warm even if they get wet.

Michael J. Gallegos / Albuquerque Tribune