SO YOU ARE LOOKING FOR A SLEEPING BAG?
There are a few things you may wish to consider before purchasing a sleeping bag for your outdoor activity such as:
- Temperature Rating
- Synthetic or Down-Filled
- Rectangular, Barrel, or Mummy
- Sleeping Pads
Temperature ratings of sleeping bags range widely. The ratings are determined by the manufacturer according to the lowest temperature the sleeping bag will still remain comfortable. Ratings generally depend on fill, construction and loft. It is advised to determine the coldest temperature you anticipate using the bag in, and then dropping that number by 10 to20 degrees to find your ideal temperature rating. The chart below can be used as a guideline. Remember, however, that ratings are not an exact science and many other human factors come into play such as body fat, fitness, fatigue, hydration, and diet which determine how warm you sleep.
|Bag Type||Temperature Rating (°C)||Temperature Rating (°F)|
|Summer Season||2° c and higher||+35° and higher|
|3-Season Bag||-12° to +2°||+10° to +35°|
|Cold Weather||-23° to -12°||-10° to +10°|
|Winter/Extreme||-21° to -50°||-10° to -58°|
SYNTHETIC , DOWN-FILLED
Outdoor s specialists usually prefer either synthetic fill (e.g. PrimaLoft), or natural fill (e.g. down), and they have debated the merits of these materials for years.
Synthetic fill sleeping bags do not readily absorb water (hydrophobic), dry easily, and provide warmth even when the bag is thoroughly soaked. This material is firm and resilient insulating well underneath a person's weight. Synthetics cannot be compressed as much as down fill bags and generally weighs more taking up more space in a pack. On the negative side synthetic insulation tends to break down faster than natural material.
Down fill weighs less than synthetic and is superior at retaining heat, however it usually costs more. Down must be kept dry; a soaked, down sleeping bag may provide even less insulation than no sleeping bag at all which could leading to hypothermia. Newer, more technically advanced sleeping bags often have water-resistant shells and can be used in damper conditions.
Whether you decide on synthetic or down fill, it is very important not to store it in bag/compression sack it comes in. Allow the sleep bag to hang. This will ensure that bag will not form any dead spots (where the fill has been crushed) no longer providing an insulative barrier.
Loft refers to volume. The greater volume of a sleeping bag translates into more trapped air resulting in warmer insulation. A quick comparison between two bags of different insulation ratings can be done by simply observing the height of a bag when lying on a flat surface. The beefier volume, height, or general ‘fluff’ denotes warmer, higher quality insulation. Technically speaking, loft is measured as volume per ounce and is a direct reflection of insulative power. Down used in most technical sleeping bags ranges from 550 Fill Power to 750+ Fill Power. A 550 down fill bag, utilizes insulation that occupies 550 cubic inches per ounce of down. A 750 Fill Power down occupies 200 more cubic inches of space per ounce!
RECTANGULAR, BARREL, OR MUMMY
Rectangular bags are suitable for warm weather, and are not the best choice for most backcountry travellers. Although inexpensive and roomy, they let a lot of body heat escape and are heavy and bulky for the insulation they provide. If you choose 2 bags with compatible zippers, it's easy to mate them and create a double bed
Barrel bags trade thermal efficiency for extra room. They have no hood, are slightly tapered, and incorporate a patterned oval foot section. They are slightly heavier and bulkier than mummy bags. These bags are especially popular with larger-frame backpackers or restless sleepers who don't like the tight fit of a mummy bag.
Mummy bags are designed to save weight and maximize heat retention. They narrow at the feet, flare out at the shoulders, and then taper to a fitted hood. With less space for your body to heat, a close-fitting bag has superior warmth to weight than a roomier bag. However, some people find them too constricting.
Sleeping bag construction methods vary in cost and the benefits provided.
|Sewn-through is used primarily in lightweight or warm-weather synthetic or down bags. Being inexpensive to make, it is prone to cold spots at quilt lines|
Offset Quilt is used for synthetic bags only construction. Since the stitching is offset there are no cold spots at quilt lines.
|Shingles are used for synthetic bags only. It is the most warmth-to-weight efficient construction however, it is more expensive than offset quilt.|
|Baffles are used primarily in down bags only. They feature mesh partitions at quilt lines to prevent cold spots and keep down from migrating through the bag. Very warm but pricey.|
Sleeping pads are integral part of the sleeping bag system. A pad cushions you against the hard ground, and keeps you warm by forming a thermal barrier between the ground and your sleeping bag. Without a sleeping pad, conduction draws heat out of your sleeping bag into the cold ground. The result? Your sleeping bag's performance is compromised, and you experience a colder night's sleep.
Inexpensive blue foam is reasonably durable, and it insulates well. Although all blue foam looks much the same, its quality varies. Squeeze the foam between your thumb and forefinger. Inferior foam will spring back slowly, if at all.
Some closed-cell foam pads feature molded-in hinges and contoured ridges. The hinges make for easy packing, while the ridges increase cushioning and insulation without increasing weight.
Self-inflating pads are more expensive than closed-cell foam pads, but they insulate well and are light and compact. Most contain open-cell foam, which is an excellent insulator when filled with air. When inflating a foam-filled pad, it's best to open the valve and allow the pad to self-inflate. Add a few breaths later if required (or use the pump system on a down-filled pad). This will prevent moisture from accumulating inside.
Store you pad unfurled and with the valve open. If required, you can wipe off dirt with a damp cloth and allow the pad to air dry. Never store your sleeping pad if it is damp, dampness encourages mildew. You can repair a punctured pad with a dab of urethane glue or a simple patch.
Check out Joe’s Sports & Surplus for your sleeping bag needs. We offer The NorthFace, Chinook, and Hotcore Sleeping systems for various temperature regimes.