Sleeping bags are arguably one of the top 5 most important items to take with you on any overnight expedition in the outdoors. So when you head to the store searching for a sleeping bag for the first time you may be surprised to find how many options you have. As with all gear guides I have or will be publishing I’ll apply my thoughts and knowledge to the topic and let you decide for yourself by getting informed. The goal of this article is that you find that the multiple options you are presented with to be less than overwhelming, and to select the right piece of equipment for the right application.
There are a handful of things to think about when selecting what bag is right for the job:
- Design Type (Rectangular, Mummy, Mate-able)
- Insulation (Synthetic, Down, Cotton/Wool)
- Temperature Rating
- Craftsmanship and Material (zipper, drawstring, fabric)
Design Type Considerations
Rectangular sleeping bags are probably the most recognizable design type to the unfamiliar shopper. It is most simply described as a filled/insulated blanket that can be folded in half and zipped on two sides to create a pocket for you to sleep in. Though they can be used in cold weather, the opening at the top of the pocket in most rectangular bags allows for a significant leak in the insulated warmth the bag provides and will allow cold air drafts to enter the bag. That being said, these bags are the easiest to pack due to their simple design and are fantastic in warm weather. Mate-able sleeping bags are most commonly a rectangular sleeping bag that are made such that you zip two of them together to create a large sleeping bag, this is a method for couples to be able sleep together (leading the type to be a double entendre?).
Mummy style sleeping bags are better for colder weather camping by design. The name describes their look perfectly, they taper from head to foot reducing the surface area and volume. By reducing the surface area and volume it takes less body heat to bring the insulation to a comfortable level, and increases their ability to keep heat from escaping. A drawstring at the head end of the bag to pull the top of the bag around your head, further increasing heat retention of the bag. Typical mummy bags do not have a zipper in the foot end of the bag because the zipper is one of the weakest points in the insulation of a sleeping bag and the toes are one of the more vulnerable parts of the body regarding heat loss. If you are purchasing a mummy bag for use by a female camper there are special considerations made by some manufacturers – construction differences in the female bags are additional material in the torso and hip areas to accommodate the differences in body type.
Insulation and Temperature Ratings
As I mentioned earlier the typical insulation used in sleeping bags are synthetic, down (feathers), cotton, and wool. The features we will be looking at specifically in each of the different types of insulation is loft(or resistance to compression), weight, water absorption and retention, and cost. Loft is important because the more space insulation takes up the greater the r-value (thermal resistance). Reducing the amount of heat lost is the goal of a sleeping bag so this is a vital consideration, though some materials have higher r-values for less material used. Weight of material is a consideration anytime weight plays a pivotal role in the amount of gear you take, specifically backpacking. Water absorption and retention is more of a consideration as for how miserable you could be if your bag gets wet.
Wool is known for its properties of water repulsion and resistance to compression though it weighs more than just about any fill material used in sleeping bags. Cotton does not repel water well at all and weighs marginally more than all materials aside from wool but it is cheap and can pack much smaller than wool. If you are going cabin camping or to a sleepover in some form these materials are a great choice for those situations and others where the drawbacks are not of major concern.
Synthetic materials provide the highest r-value per inch versus the other fill materials, have the best water absorption and retention qualities (virtually none of either), dries easy, and even provides insulation while wet – a lifesaving feature that can prevent common cases of hypothermia while wilderness camping. Synthetic fill also insulates well under compression (like laying on the bag, for instance) and lofts quickly to provide maximum insulation faster. The drawbacks to these properties are that it does not compress easily and therefore requires more space to store than easily compressed materials, it also weighs more than down. Down fill is one of the best heat retainers of fill material by density. It also costs the most, and is nearly useless when wet.
Craftsmanship and Material
As with most things, the quality of the material and attention to detail in the craftsmanship in sleeping bags is directly proportional to the life of the bag. A couple of things you may want to look out for when choosing a bag is the zipper and material surrounding the zipper. Will the zipper get caught in the bag? Will the zipper jam easy or bind on itself? One of my favorite bags had a nylon webbing material that surrounded the zipper teeth such that the fabric on the inside and outside of the bag were kept out of the way of a closing zip. Unfortunately, the zipper pull itself was not constructed of hardened material and the zipper failed due to other circumstances. Another feature to check the material and craftsmanship on is any drawstring attached to the bag. Is the drawstring secure to the bag, or simply attached by a single stitch at a fold? Is the cord itself resistant to rot over long periods of time? Lastly, the fabric used for the inside and outside of the bag needs to be investigated. Is the fabric thin and easily worn out after a few dozen times in and out of the stuff sack or is it durable? Does the external shell of the bag resist water, stains, or other environmental factors that may play a part in the breakdown of material? Does the inner material warm up quickly to the touch? All of these questions should be in the back of your mind when investigating the construction of a sleeping bag.
Care and Storage
Care of your bag will be a concern if you plan to keep the bag for many trips, particularly keeping it clean. After each trip I take, I open my bag and turn it inside-out to lay it on a clothes line or the back of a couch. Airing it out helps prevent it from getting smelly quickly. If after a dozen trips or more it gets to the point where it no longer supports breathing, there are specialized detergents designed with your sleeping bag and other camping gear in mind. Most, if not all, sleeping bags will include instructions for washing on a tag either attached to the bag or a storage sack. Typically they will tell you to use a hand washing method, or a front-loading (non-agitating) washing machine with light amounts of detergent (like woolite or a specialized soap) in warm water. Air drying or press drying are highly recommended for drying a washed sleeping bag. Do NOT dry-clean a down sleeping bag unless the manufacturer explicitly recommends it, as the chemicals used will strip the feathers of natural oils necessary in keeping the insulating value of down.
With all materials settling will occur causing cold spots to appear in the bag if care is not taken to minimize the amount of settling. Down is the fill material most affected by this, so much so that while in periods of extended storage it should be kept in a large back so it is not forcibly compressed. Short periods of time, like while packed in a backpack, are okay for this compression but will continually degrade the loft and insulation characteristics of the bag.