IMPORTANT FEATURES OF SLEEPING BAGS

TEMPERATURE OR COMFORT RATINGS

The first consideration in buying a bag should be how comfortable it will keep you when outdoors. Sleeping-bag manufacturers assign a comfort or temperature rating to their bags to help consumers determine the best bag for their uses. Basically the rating refers to the lowest temperature at which the bag remains comfortable.

Unfortunately, most comfort ratings are overly optimistic and vary widely between manufacturers. The ratings assume you are an average hiker under normal conditions. The problem lies in trying to define who is “average,” what conditions are “normal,” and what is considered “comfortable.” These ratings do not take into account whether or not you are hungry or well fed, hydrated or dehydrated, whether you just hiked 1 mile or 20, or whether it’s snowing or the hottest day on record. The ratings also do not reflect the benefits of wearing clothes (you’ll be a lot cooler sleeping in the nude and a lot warmer wearing long johns) nor whether you are sleeping in a tent or out in the open (nothing cools you faster than being exposed to bone-chilling wind).

The useful information that comfort ratings provide is the idea of relative warmness. A 10-degree bag will keep you warmer than a 20-degree bag and, when comparing reliable companies, a 20-degree bag from one company will be in the rough ballpark of another’s 20-degree bag. This situation should soon be improving. An agreement among 22 European countries will standardize comfort ratings (based on lab tests using a mannequin) for bags sold on the continent. These European ratings should quickly filter into American usage, allowing shoppers to make apple-to-apple comparisons when buying a bag.

Before deciding on a comfort rating, try to determine the range of temperatures in which you will most often be hiking while on the A.T. This can be a challenge, especially for section or thru-hikers, who can cover a wide range of elevation changes (and the ensuing temperature and weather changes) during a trip. It is better to buy a warmer bag (or at least, a bag liner or overbag) than you think you will need than to face a 20-mile day after a cold and sleepless night. If it’s too warm to slip into your bag, you can always sleep on top of it! If you intend to do a lot of cold-weather camping, you’ll probably want a bag rated between zero and 20 degrees, though for most three-season hiking on the A.T. a 20-degree bag should be adequate. If your hiking will take you through both cold and hot weather, a combination of sleeping bag and bag liner can extend the range in which your bag keeps you warm. Of course, if money is no object, you may prefer to buy several bags with ratings ranging from zero to 45 degrees.

Some people choose to cut down their backpack weight by carrying a blanket (and in one case we know of, a table cloth) instead of a sleeping bag. It is unwise to forfeit your sleeping bag for the sake of weight. Any meteorologist will admit that weather is unpredictable, seemingly changing at whim from hot and muggy to cold and stormy within 24 hours. During our backpacking career, we have had both our coldest and hottest days in Pennsylvania in June. We definitely recommend that you purchase a sleeping bag, even if you only intend to make overnight trips. It’s the difference between sleeping warm and shivering wide-awake and could be the difference between life and death.

“You can endure great hardship as long as you can sleep warm.”

—SIR FRANCIS GALTON, THE ART OF TRAVEL, 1867

SLEEPING-BAG FILL

Down bag (GoLite Feather Bag)

Hard as it might seem to believe, sleeping-bag-fill technology advances almost yearly. Regardless, there are six main categories into which these stuffers have been delegated: down, the old synthetics, the new or short staple synthetics, the continuous-filament synthetics, pile or fleece, and proprietary synthetics. Keep in mind that the primary concern that should influence your decision when choosing a fill is what happens to that fill when it gets wet, though weight and packability are also important concerns. Once again, your choice will be a question of preference.

DOWN: Down has long been lauded and is still number one when it comes to providing maximum warmth and comfort for minimum weight and bulk. Down sleeping bags breathe better than polyester fiber bags and are less stifling in warmer temperatures than their synthetic counterparts. But when a down bag gets wet, it loses almost all of its ability to warm and gains much more in weight than synthetic bags. Down bags also mat and clump worse than synthetic bags. Down bags are notoriously bad for hay-fever sufferers. If you’re allergic to feather pillows, you’ll be allergic to down bags.

Both goose down and duck down are used as fillings, with the difference discernible only under a microscope. But goose down is generally considered structurally superior. The fill power or loft of down is measured in cubic inches and simply represents the number of cubic inches 1 ounce of down will expand to in a 24-hour period. For example, 600 cubic inches is considered to be a superior loft, 500 to 550 is very good, and so on. That infamous “do not remove” tag will inform you of the bag’s loft. By the way, for you, ultralight hikers, the consumer is allowed to remove the tag once the product has been purchased.

“OLD SYNTHETICS”: Quallofil and Hollofil/Hollofil II. You can find these synthetic fills in the budget bags these days although just a few years ago they were considered state-of-the-art. While they will keep you warm when they get wet, these fillings are a lot heavier and bulkier than the newer synthetics.

Quallofil fibers are hollow, and feature four microscopic tubes that allow for good insulating ability and increase fiber surface area. This polyester filling, which is as soft as down, is nonallergenic and retains most of its loft when wet so that it doesn’t become thin and hard or lose its warmth.

A type of polyester, Hollofil fibers are about two inches long and must be sewn to a backing to prevent clumping; this leads to cold spots in a sleeping bag. Similar to Quallofil, Hollofil has a single hole in the fiber; but it allows for more “air” per ounce and thus provides more insulation. The added insulation is gained at a price because the backing materials used for the filling add weight. Like other polyester fills, Hollofil loses only about a tenth of its warmth when wet. The newer Hollofil II has silicone added to make the fibers easier to compress and the bag, therefore, easier to push into a stuff sack.

Synthetic bag (The North Face Cat’s Meow)

NEW OR SHORT STAPLE SYNTHETICS: Lite Loft, Micro-loft, Primaloft, Primaloft 2, Thermolite Extra, Thermolite Extreme. These fills come pretty close to matching down’s warmth and softness. They are also a good deal lighter and more packable than down. But, unlike down, heavy-duty use reduces their loft.

Thinsulate Lite Loft by 3M is the warmest synthetic insulation available for its weight. Its microfine polyester/olefin fibers make it lightweight even when wet and easily compressible. Microloft is made by Du Pont and boasts the smallest of the microfibers. These tiny fibers enable Microloft to trap more heat and remain soft and supple. The Primalofts mimic the structure of goose down with tiny fibers interspersed with stiffer fibers. Unlike down, Primaloft is water repellent and retains its warmth when wet.

CONTINUOUS-FILAMENT SYNTHETICS: Polarguard, Polarguard HV, Polarguard 3D, and Polarguard Delta. More durable than the short staple synthetics, these fibers, which are long and interwoven, don’t become matted, which eliminates the need for a backing to prevent cold spots. Polarguard HV also retains its loft—thus its warmth when wet. The new Polarguard Delta and Polarguard 3D perform best, though they tend to be bulkier and heavier than the short-staple synthetics.

PILE OR FLEECE: Pile works great for a jacket, so why not a sleeping bag? The bulky material tends to be used in inexpensive bags. Though fairly lightweight, they are really only used in a few warm-weather sleeping bags and are not a good three-season option. Some overbags and bag liners use fleece to help boost your sleeping bag’s rating for colder weather.

PROPRIETARY SYNTHETICS: These are synthetic fills produced by the manufacturers of some sleeping bags to fill their own bags. Quality varies according to manufacturer. You will want to check the Internet for online ratings of these by other hikers before making a purchase.

According to tests conducted by Recreational Equipment Incorporated (REI), “a synthetic bag will lose about 10 percent of its warmth while gaining about 60 percent in weight” when the sleeping bag gets wet. Conversely, they report that a water-soaked, down-filled bag “will lose over 90 percent of its warmth, gain 128 percent in weight, and take more than a day to dry.”

What this means is that your ability to keep a down bag dry is a major factor when deciding to purchase a bag. All six fills have strong proponents. When purchasing a bag, decide how much trouble you want to go through to keep your bag dry. Stuffing your sleeping bag into a plastic garbage bag before putting it in a stuff sack will keep it dryer. And if you will be fording a stream or are expecting hard rains, put the stuff sack into another bag for extra protection.

WEIGHT

In conjunction with comfort rating and fill, weight is the third element in considering which bag to buy. Weight is related to the comfort and fill rating. Usually, the lower the comfort rating, the more the bag weighs. However, within a given comfort rating, bags will vary quite significantly given different fills. Generally, the lightest bag that gives you the greatest warmth for your comfort needs is best. Unfortunately, the lighter the bag, the more it’s going to cost. As a rule, do not buy a bag that weighs more than five pounds. For A.T. backpackers, a bag in the two- to four-pound range is probably the best bet for cost-efficiency and warmth.

Keep in mind that it is likely that the bag you buy will eventually get wet, and that its weight will increase as a result.

OTHER BAG CONSIDERATIONS

SHAPE

Sleeping bags come in three basic shapes: mummy, rectangular, and semirectangular. Most backpackers choose the mummy-shaped bag because it offers the most warmth and space for the least weight. Most bags offer what is called a draft tube behind the zipper to prevent air from leaking into the bag. If you intend to use your bag in windy or even cool weather be sure that the bag you choose has a draft tube.

MUMMY: The name describes the shape. Formed to the contours of your body, the mummy has the least amount of air to warm and takes less material to make (and, therefore, to stuff). This saves on weight as well. The mummy’s “head” is designed to draw down over and around your own on cold nights, limiting your body’s heat loss. Most mummy bags also feature a “boxed” foot section, which keeps the insulation in place over your feet so that they stay warmer. But like everything, the mummy has its drawbacks. There is absolutely no room to turn around in it. You either toss and turn the entire bag or sleep in one position through the night. Also, the short zippers hamper ventilation.

RECTANGULAR: This is the roomiest and the heaviest of sleeping bags. Three sides of the bag are zippered, allowing you to ventilate to the point of making the bag a blanket. Room and ventilation become the bag’s drawbacks on cold nights because there is more air to heat and no hood to prevent heat from escaping through your head.

SEMIRECTANGULAR: This bag has the taper of a mummy bag without the hood. The design saves some on weight, provides good ventilation because it, too, is zippered on three sides, and has a bit less air to heat up. Like the rectangular bag, there is no hood for cold nights. It is a good choice for large-framed hikers who don’t mind carrying the few extra ounces.

When purchasing a sleeping bag, make sure it fits. A bag that is too narrow or too short will affect the quality of your sleep. Because a mummy bag follows the contours of your body, make sure that it is not too tight in the shoulders and around your head. If you are planning extended backpacking and/or cold-weather trips, you may want to buy a bag with extra room at the feet. The extra room will accommodate water bottles, boots, socks, or any other things you may want to keep from freezing.

SHELLS

Another important consideration when buying a bag is the shell or outer covering. Although there are numerous materials to choose from, you will want to consider only shells made from DryLoft, Epic, Microfiber, Pertex Endurance, ripstop, and taffeta.

DryLoft is made by W. L. Gore and is a highly breathable and water-resistant fabric. DryLoft is very similar to Gore-Tex and will hold at bay wind, condensation, and light rain. In a sleeping bag with a DryLoft shell, you can sleep under the stars or in a snow cave without having to worry about waking up cold and wet.

Epic by Nextec encloses polyester microfibers in a very thin silicon-based polymer film. A durable, breathable barrier is then created between the fiber bundles. The soft fabric allows body vapor to escape, keeping you drier.

Microfiber is a tightly woven nylon or polyester fabric that is usually more supple and lighter than DryLoft. It is, on the other hand, less resistant to water than both DryLoft and Gore-Tex. But it does repel wind and breathe well.

Pertex Endurance faired well in a 2004 Backpacker magazine test claiming that this material “raises the bar for repelling moisture.” The only negative is that many bags made with the fabric are not seam-sealed and not as water repellent as they would otherwise be.

Ripstop nylon and polyester feature heavier threads interwoven in the fabric every quarter inch or so in a checkerboard or diamond pattern to prevent rips from running down the bag. It also forms a web of reinforcement to reduce stress. Strong for its weight, ripstop nylon is also wind resistant. On the other hand, it does not repel water and therefore gets wet easily—although it dries quickly.

Taffeta is a flat-weave fabric that is softer than ripstop but isn’t as strong or as resistant to wind. It, too, gets wet easily. Nylon taffeta is often used as an inner lining.

As with sleeping-bag fillings, some manufacturers make their own proprietary shell materials, which are hard to assess. Once again, checking online ratings at a site like www.epinions.com can help separate the reality from the manufacturer’s potentially hyped advertising.

MATED BAGS

For couples interested in hiking, some sleeping bags may be zipped together. Many sleeping bag manufacturers offer bags with right and left zippers. If you intend to buy mateable bags, you may want to consider one lightweight (approximately 40-degree) and one heavier (about 20-degree) bag. That way, if it’s warm, you can use the cooler bag on top—and vice versa.

ADDED FEATURES

Some extra features you might want to keep in mind when purchasing a sleeping bag include:

OPTIONAL FABRICS: Some manufacturers will allow you to pick which shell fabric you want on the bag.

BRUSHED INNER LINING: This fleecy lining feels soft and cozy on cold nights. On muggy nights, this lining can wick away the perspiration from your body but some people claim the lining holds in too much heat.

INSULATED DRAFT COLLAR: This is a puffy yoke or collar that can be cinched closely around your neck (usually with a drawstring) to keep the warm air in the bag and the cold drafts out of it. A draft collar makes a huge difference in how warm you stay on a cold night.

HOOD: As most people know, most of your body’s heat is lost through the head. That’s what makes wearing a hat so important in cold weather and, similarly, what makes having a hood on your sleeping bag so important in frigid conditions. Look for a hood with a contoured cut that is snug but not too tight and that features plenty of insulation. Some hoods use elastic to snug the hood, others feature a drawstring.

POCKET: Some sleeping bags feature a zippered pocket at chest level to provide you with handy storage of things you might want to keep close by, such as contact lenses, a flashlight or headlamp, and lip balm. This works well for those who can maintain a single position throughout the night.

STORAGE BAG: This is a big, breathable cotton bag designed to prolong the life of your bag when you are not using it. If you cram your bag into its stuff sack and forget about it for a few months, it will lose its loft.

ZIPPER OPTIONS: This essentially means that you can choose whether or not you want a right-handed zipper or a left-handed zipper or whether or not the zipper can be mated with another sleeping bag.

INSULATED ZIPPER DRAFT TUBE: This is basically a draft collar for your zipper and is a wonderful option. The tube should hang from the top of the zipper so that it stays in place over the teeth.

WOMAN’S MODELS: Some sleeping bags are designed with a woman’s needs specifically in mind, particularly some models from Sierra Designs. What does that mean? Usually these bags feature extra width at the hips and less at the shoulders, more insulation in the foot box, and less overall length.

CARING FOR YOUR BAG

Synthetic sleeping bags can be washed by hand or in a commercial washer with warm or cold water. They should be cleaned with a mild soap such as Ivory, and, if not air dried, they should be dried at a low setting in your dryer. When air-drying any bag, make sure it is well supported. Never hang it by one end because the weight of the wet filling may tear out the inner construction and ruin the bag. Supporting the bag on a slanted board is a good option. Don’t wash your sleeping bag after every trip. That stresses the fabric. Rather, wash it only when it is really dirty.

Down sleeping bags should be hand washed. If washed in a machine, your bag could lose its loft because the detergent breaks down the natural oils of the goose down. Down bags should not be dried in a household dryer; rather, they should be drip dried for several days. The bag can then be placed in a commercial dryer on low heat to fluff it. Throwing in a clean pair of tennis shoes will break up matted down.

Sleeping bags should not be stored in the tiny stuff sacks that they are normally carried in on a hike. A big, loose bag is the best container for keeping your bag in good condition when you’re not on the trail. Stuffing your bag into a small sack every day while hiking is all right because you’re taking your bag out almost every night. But if you store it that way at home, the filling becomes packed together and it is hard to restore its loft. Never roll your bag up neatly because this compresses the insulation. Stuffing the bag into its sack assures you of a different pattern of compression each day, which is better on the loft.

Another way to increase the life of your bag is to wash up each night before crawling into it. The dirt and oil on your clothes and body will find its way into your bag’s fill and inhibit its ability to insulate. If you can’t wash up, change into clean clothes.