Wool: Why It Is the Fiber for Cold, Wet and Long Days, and What to Own in It

Because the situations where clothing decides the outcome are cold and wet, and wool is the only common fiber that keeps working in both. It insulates when soaked, it takes on a third of its weight in water before it feels damp, it does not melt or flare near a fire, it does not stink after days of wear, and it lasts for years. Cotton kills in the cold, synthetics melt and smell, down collapses when wet. Wool does none of that.

Yes. The crimp in each fiber traps air even when the fiber is wet, and wool can absorb up to 30 percent of its weight in water before it feels damp on the skin. As it absorbs water it releases a small amount of heat, and it moves moisture away from the skin as vapor. A soaked wool sweater is heavy and cold to touch and still warmer than anything else you could be wearing; a soaked cotton sweatshirt is a wet towel that pulls the heat out of you.

Naturally, yes. It needs a high temperature to ignite, it chars rather than melting, and it goes out on its own when the flame is taken away. That is why a wool blanket is the one you sit by the fire in and throw over a small fire, and why synthetics, which melt into the skin, are not. It is not fireproof; it will burn in a fire, just slowly and without sticking to you.

Wet wool is heavy and slow to dry, so a soaked wool coat on a long walk is a burden a synthetic is not. It shrinks and felts if it is washed hot or tumbled dry, so it needs care. Good wool costs more up front, though it lasts many times longer. Coarse wool itches some people. And moths eat it in storage, so it lives in a sealed bin with cedar.

For warmth when wet, for fire, for odor and for the long haul, wool wins. Synthetics dry faster, weigh less and cost less, and are the better outer layer in rain and the better choice for a hard-sweating climb. Down gives the most warmth for its weight, and is useless the moment it gets wet. The answer in a kit is layers: wool against the skin and on the feet and head, synthetic or down in the middle, a shell on the outside, and a wool blanket for camp.

True wool allergy is rare. What most people call a wool allergy is the itch from coarse fibers, about 30 microns and thicker, prickling the skin. Fine merino, under about 24 microns, does not do it, which is why merino base layers and socks are comfortable for people who cannot wear a coarse sweater. A few people react to lanolin, the natural grease in wool, and superwash-treated wool has most of it removed.

In this order. Socks, medium or heavyweight merino, two pairs per person, because feet are where cold and blisters end a day. A base layer, top and bottom, in merino, worn against the skin. A hat that covers the ears, because that is where the heat goes at night. A blanket, 80 percent wool or better, 60 by 80 inches, which is a bed, a coat, a shelter wall and a fire blanket. Then a sweater, gloves and a coat as money allows. Military surplus is the cheap route for the blanket and the sweater.

Cold water, a wool wash or a mild soap, no agitation, no wringing, and never the dryer. Hand wash or use the wool cycle, press the water out in a towel, and dry flat or over a line out of the sun. Heat plus agitation is what felts wool into a child's size. Between washes, air it out; wool does not need washing nearly as often as anything else, and the blanket gets washed once a year at most.