On some backpack trips you hardly need any clothes at all, but in the high mountains it becomes cool or cold at night, even in midsummer. It may freeze any night in the year. Your good down sleeping bag will defeat the cold once you go to bed, but as soon as the sun goes down (which may be as early as 3 P.M. ) you will want to put on something warm. And unless you sleep very late, you will want to put on something warm in the morning. There may be entire days when you’ll want to wear something warm.
What keeps you warm is an envelope of warmed, still air around your body. If air would stick to your body like molasses, you would be warm naked on Mount Everest . But air doesn’t stick—it circulates. First, your body heats the air close to it, and this heated air rises and moves away. Then some cooler air flows in to take its place. So you need something to impede air movement. The thicker this something is, the thicker is your envelope of still air.
Naturally, when you’re cold, you’ll want to put on all the clothes you brought. By selecting these layers carefully, you can assure yourself of being warm and dry as efficiently as possible, which is vital when you carry every pound. The clothing layers are divided into four categories: long underwear, shirt and pants, insulation, and wind/rain shell. By adding or removing one or more of these layers, you should be able to get comfortable over a wide range of ambient temperatures and levels of activity: from working up a sweat hiking in cool weather to sitting around after dinner on a cold evening. Likewise, you’ll be prepared for rain and wind.
Underwear
The underwear layer has seen a significant technological advance with the use of polypropylene (known as “polypro”). This fabric has gained great popularity because of its light weight and its wicking ability. Wicking is the process whereby polypro (and some other fabrics), when next to the skin, carries moisture away from your skin. Moisture is wicked to the outside of the garment, where it can evaporate without cooling the wearer as much as if it evaporated right next to the skin.
Polypro has disadvantages too. It retains body odor remark ably well, so after prolonged use it smells terrible. When washing it, you must avoid heat: use cool-water wash and no dryer. There are some similar fabrics that achieve the same wicking effect and don’t have some of polypro’s drawbacks.
Two natural fibers—silk and wool—also work for the under wear layer. The high price of silk deters many people from using it, though it works quite well. Wool can be uncomfortable next to the skin but it has the advantage of keeping you warm even when it is wet. Avoid cotton for active pursuits in cold weather, as it will chill the body when any moisture in it slowly evaporates.
Clothing
The next layer outward is the clothing layer. This can be any of a variety of articles of clothing, preferably something absorbent that will help draw moisture through the underwear layer to where it can evaporate away from the skin. This layer is usually the long-sleeved shirt and long pants—or shorts—you’d wear in mild weather. More on that later.
Insulation
The third layer is the insulation layer. Here your choice of garments can vary considerably according to your personal preference, your budget and the temperatures you expect to face. If you don’t expect very cold temperatures, the possibilities include a wool sweater or one of the newer synthetic pile or fleece jackets. I prefer a jacket that zips up the front for easy ventilation and easy removal. The advantages of pile and fleece jackets are that they are lightweight, keep you warm when wet, and dry quickly. These jackets are expensive compared with an old wool sweater you may already have or can buy cheap at a thrift store.
If you expect cold temperatures or get cold easily, you will need to supplement this layer with an additional sweater or vest, or use a warmer jacket. A down jacket is a lightweight option that offers warmth and protection from wind. You must not get it wet, or it will become almost worthless for keeping you warm.
As with sleeping bags, the nearest equivalent to down-filled garments is synthetic-filled garments. Heavier filling is required to confer the same amount of warmth, but synthetic garments don’t lose much of their warming ability when wet. They also cost less than comparable down garments.
Rainwear and Windwear
Finally, you have an outer shell to protect you from wind and rain. Whatever stops water stops wind. You want an outer layer that will keep you dry in the rain and warm in the wind. Until recently, any garment that was totally impervious to water would keep all the rain out, but it would get you very wet by keeping your body vapor and your sweat in. Now you can buy an outer garment made of nylon coated with Gore-Tex or another water proof but breathable fabric. As noted earlier under “Sleeping Bags,” Gore-Tex presumably keeps out rain but lets out your body vapor.
Waterproof-breathable fabrics work because they have very tiny pores. Water in its liquid phase won’t fit through these pores, but water vapor (a gas) will fit through them. There is a limit to the breath-ability, however, since some of your body moisture condenses before it reaches the Gore-Tex. Leakage can be a problem in Gore-Tex garments at the seams if they are not sealed (most should be factory-sealed with tape) or when the garment is dirty. The garment may also leak at pressure points like shoulders under straps and at the knees when kneeling.
Gore-Tex parkas are expensive. You can get by more cheaply with a poncho, which is so loose-fitting that it has many places for your body moisture to get out—and rain to get in.
Fig 3-1: Rain parka with hood; Poncho covers more, flaps more
in wind
As for the style of the rain-wind garment, I wear a hooded Gore-Tex parka with full front zipper. Like all good mountain clothing, it opens down the front, so I can wear it open or closed to adjust the amount of heat retention. This style is also easier than a slipover to get into and out of. If I am pretty sure it will not rain during my trip, I save about 3/4 pound by substituting for my parka a thin, uncoated nylon windbreaker. One attraction of my parka is the four large pockets in front and the one super-large pocket across the back. If my pack is too full, I can put some things in the pockets of the parka, which travels on top of the pack, ready for instant use if rain or wind comes up. And the pockets carry all I need for a day’s hike away from base camp. Be sure you get a parka large enough to fit loosely when you wear it over all your other clothing. Also be sure it has drawstrings at the hood and waist, and some device for closing the wrists snugly.
Since skin dries quicker than clothing, I prefer to keep hiking in my shorts and t-shirt during a short rainstorm on a warm day, rather than stop, retrieve my raingear from my pack, and over heat while hiking with the raingear on. I stay plenty warm while hiking, and am no wetter than I probably would be with my sweaty clothes under raingear.
Rain pants are not a necessity, but during a downpour or walking through wet brush, you’ll appreciate keeping your lower half dry. If your rain jacket is not long enough to cover your backside, rain pants are a must, to keep the water that’s dripping from the bottom of your jacket from soaking your hiking pants. Rain pants also prevent the water that pours down your legs from filling your boots.
Think ahead to stay comfortable. Add layers before you get chilled and unzip or remove layers as you become active. Don’t let yourself get all sweaty before you remove your jacket.
Vapor Barriers
Vapor barriers have been touted as an excellent way to stay warm and dry. Though the reasoning is sound, the idea hasn’t caught on. This may be due in part to the uncomfortable feel of a waterproof fabric right next to the skin. Regardless, this is how it works:
If your skin weren’t slightly moist, it would crack and bleed. Not surprisingly, the body has a built-in mechanism for keeping the skin moist. When triggered, this mechanism turns on the organs for making “insensible sweat”—which is water vapor as distinguished from “sensible sweat,” which is water. What triggers this mechanism?—the drying out of the skin, of course. Now, skin exposed to air dries faster than unexposed skin, but skin under a garment also dries out—unless the garment is vapor-proof. Breathable fabrics are not vapor-proof, and they allow body vapor to pass outward, into the surrounding air and also, of course, into the surrounding clothing such as a down jacket. As the vapor passes outward, the skin humidity starts to fall, so the organs produce more insensible sweat. The clothing is cool enough that the water vapor condenses in it. This water in the clothing makes it far more conductive of heat—20 times as conductive as dry air. So the garment you have put on to help you stay warm begins to conduct heat away from you at a rapid rate.
This whole process is accelerated when you are in cold air, because cold air is dry air. Being dry, it gobbles up your water vapor faster, your skin-wetting organs have to work faster, and more water condenses in your garments. (It also condenses in your sleeping-bag insulation when you are in the bag.) The water that condenses in the clothing eventually re-evaporates, when it has absorbed enough of your body heat to vaporize it. It takes 555 times as much heat to vaporize a gram of water as to raise its temperature 1°C and all that heat comes right from your body.
How to avoid this chilling? Vapor barrier theorists say you should wear, right next to the skin, garments that are absolutely impermeable to water. (Some allow wearing a thin layer of polypro under the vapor barrier to minimize its slippery feel.) They also recommend that in cold weather you wear plastic sacks on your feet under your socks, and cheap plastic painters’ gloves on your hands.*
When you wear a vapor barrier, your skin stays moist even with very little output of insensible sweat, and none of it can get into your clothes. Hence your clothes stay dry and give you the maximum insulation they are capable of. On the outside, you can wear a waterproof garment because there’s no need to let body moisture escape. But since the barrier won’t let water out, you can’t afford to let yourself start to sweat profusely. Opinion among vapor-barrier theorists varies on how to solve this problem. Your options include ventilating through zippers under the armpits to let out heat, opening outer garments at the neck as soon as you notice any sensible perspiration, and removing those outer garments.
The opposite view, of course, is the breathability view, and it is still the majority view. Gore-Tex and other similar fabrics are merely the latest in a long series of answers to the question of how to let out our body moisture while barring the rain from coming in through our clothes. Breathability advocates say that when you wear a vapor barrier while exercising, as in backpacking, you are bound to nearly drown in your own sweat. I personally find it very hard not to overheat, even with underarm zippers, unless I remove some garments as I heat up. If it’s raining, that presents a real problem, and of course you have to take your pack off to add or subtract garments. Nevertheless, I often use vapor barriers.
Vapor barriers in sleeping bags are more common than vapor- barrier clothes. It makes sense: when you’re asleep, there’s no problem of avoiding overheating and consequent sweating. A vapor barrier will add more warmth to your bag than an equal weight of additional down, and it eliminates the need to dry your bag before you pack it the next day.
* The owner of Warmlite Company enjoys telling how, in Vermont where she lives, she always carries a supply of plastic gloves when she goes skiing. When she encounters a skier with cold hands, she gives the person one plastic glove to wear under a ski mitt. Very soon, she says, the person notices the difference between the two hands, and approaches her to ask for a second plastic glove.
Shirt and Pants
Fortunately, you don’t need to buy high-technology shirts and pants. Because your clothes always take a beating in the wilder ness, wear the toughest material you can get. If you may run into cold, wet weather, choose wool. Wet cotton can literally lead to death. The more pockets you have, the better. Choose a long sleeved shirt that can be buttoned at the neck. It will protect you from the sun and mosquitoes. To cool off, unbutton the neck and the cuffs. To warm up or to avoid mosquitoes, button up.
Many hikers prefer short pants for walking, but short pants are silly in brushy country, and no help in mosquito land. Some hikers carry both shorts and longs, and some are switching to overalls.
On most trips, no change of clothing—except socks—is necessary. If anything gets so dirty or smelly that it bothers you or your companions, wash it and let it dry in the sun while you do other things.
Hat
I don’t see why anyone would backpack without a hat. The mountain sun shining on your head can make you downright ill, and the desert sun can kill you. Unshaded eyes are subject to their own painful version of sunburn. In addition, your poncho hood or parka hood, even though you put it up during rain, probably won’t keep wind-driven rain out of your face and eyes, but a hat brim usually will. Finally, a hat is a garment you can use to cool off or heat up. For instance, on a hot day, push the crown up to create a larger dead-air space between your scalp and sun’s hot rays. For bald people, a hat is an even better device for regulating temperature. Since about one third of the heat your body radiates is given off by your head, you can hold in a lot of heat by putting on your hat, or get rid of a lot by removing it.
Your hat should have a wide brim all around, as a barrier against both sun and rain, and it should be able to take a lot of hard use. Choose one with an ample crown, not a flat top. Give it some water repellency by spraying it with a repellent. But don’t wear a waterproof hat; it won’t let out the water vapor your head gives off, and your head will be drenched.
If you expect cold temperatures, bring along warm headgear too.
Fig 3-2: various hats
Bandana
Experienced hikers play the game of finding new uses for the bandana. Beginners know that a large bandana makes a good out- of-doors handkerchief, and then they see it can be a washcloth. It can also be a dishcloth, a towel, a pot holder, a scarf, a makeshift hat (knotted in each corner), a mosquito net for the face while napping, a sling for an injured arm, a tourniquet, a bandage, a food cover, a headband to keep hair and sweat out of eyes, in ever-ready rope for tying things, a wrapper for freshly caught trout, a visible warning tied to clothesline or tent guy-lines in camp so that people don’t walk into them, a signal flag (if it’s red), a swimsuit, and a carrying bag for side trips. For me it is everything but a towel; my towel is super-absorbent rayon.
Swimsuit
Oddly enough, some law of nature seems to be eliminating the need for a swimsuit just when one is becoming necessary. A few years ago, the wilderness hiker could usually find a private place to bathe, and didn’t need a swimsuit. Now it is much harder to find privacy; however, many wilderness travelers’ attitudes toward nude swimming are changing. You’ll have to decide for yourself each trip whether you want to carry the few extra ounces of a swimsuit.
Of course, underwear works too.
Gloves
I strongly recommend a pair of cheap cotton gloves. When you are breaking firewood or moving fireplace rocks around, gloves minimize cuts and punctures. When mosquitoes are peskiest, gloves protect the back of the hand and the wrist. When it is cold, they give warmth. They also substitute for a pot-grabber (see Section 4) and may weigh no more than one.
In colder seasons, take a pair of wool gloves instead.
Sleepwear
Sacrifice all else to stay warm and dry, have happy feet, and sleep well. If you need a pair of pajamas or a nightgown to sleep well, bring it. Most people quickly get used to sleeping in their clothes, their underwear or nothing.
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