Sleeping Bag - Buying Guide
Introduction
Sleeping bags are made to various standards and price points depending on the intended use. At first glance it may not be apparent what all the differences are.
What type?
The main difference in a sleeping bag is the insulation that is used. Generally speaking the more expensive the bag the better or more advanced the filling material will be. This will allow the bag to pack smaller and lighter.
Down
Good quality down filled bags are usually lighter and will pack down to a smaller size than an equivalent synthetic bag. They will also keep you comfortable in a wider range of temperatures than an equivalent synthetic bag. If looked after the bags will last significantly longer. The main disadvantage with down as an insulation is the fact that if it gets wet it will lose a great deal of their insulating properties.
Down generally comes as either Duck down or Goose down. Usually duck down is slightly cheaper and the goose down being finer has better insulation properties. However the quality of the down used in a bag will have a significant effect on the warmth. The quality of down is measured in “fill power”. This is a measure of how much space 1oz of down will fill (i.e. 750 fill power will mean that 1oz of down will fill 750in3). Fill powers usually range from 550 to 800.
Synthetic
Synthetic fillings are less expensive to produce than Down and will retain the majority of their insulating properties even when wet. They will also dry out quicker and are easier to care for as most can be machine washed.
Synthetics come in a range of qualities here are just a few types:
Hollowfibre: a collection of polyester fibres, each with a single hole (like a straw). This is the most basic fibre used in any of the bags that Craigdon sell.
Siliconised hollowfibre: This is the next stage up, where the fibres are coated in silicon. This makes the fibres more durable.
Insulite 3D spiralised: This filling is a siliconised hollowfibre that has been twisted into a spiral. This crimping allows each fibre to trap even more air providing more insulation.
Temperature/Season ratings explained
Sleeping bags will either be rated in seasons or given a temperature rating. Both these ratings assume that the bag will be used in a tent on top of an adequate sleeping mat. The season rating is a general guide and is as follows:
1 season Summer (or indoor) +25 to +15?C
2 season Late spring to early autumn +20 to +10?C
3 season Early spring to late autumn +15 to +5?C
4 season Winter +10 to -10?C
5 season Expedition /high altitude use +5 to -20?C
Temperature ratings give an idea of the range of temperatures that the bag can be used in. Usually there are the following figures quoted:
Upper temperature limit: This is the warmest temperature that the average male could use the bag with the zip open and sleep without being too hot.
Comfort temperature: This is the lowest temp that the average female would be able to sleep whilst wearing light clothing having the hood and zips etc fully shut.
Comfort limit: As above but the average male.
Extreme rating: This is based on the average male fully clothed curled up for 6 hours. Although you will be alive you may be suffering from frost bite or even be hypothermic!
These ratings should always only be treated as a guide as there are a number of factors that will affect how you feel in a sleeping bag. These can be physiological such as age, physical fitness, body weight, how well nourished and hydrated the user is. Physical factors like the environmental conditions and altitude can also have an effect on your experience.
Construction methods
Down bags:
Stitched through construction
This is the simplest construction where the stitching goes right through the outer and the lining of the bag. This is only suitable for 1-2 season bags as there will be little or no insulation where the stitching is.
Box wall construction
This style comes in many different forms but basically the bag has small walls or baffles stitched in either vertically or offset this eliminates the cold spots and allows the down to loft better
Synthetic Bags:
Stitched through construction
This is the same as in the down bags. It is by far the most cost effective construction method but is only suitable for 1-2 season bags.
Double construction
This is where two layers of insulation are used and over lapped to eliminate cold spots (some manufacturers will call this offset quilting).
Shingle construction
Slabs of insulation are sewn between the outer and inner of the bag – a bit like slates on the roof of a house, they overlap and this eliminates any cold spots. This is the most effective warmth to weight construction but is also the most expensive.
Features and what they do
Neck yoke or shoulder baffle: This is an adjustable collar at the neck/shoulder area. This stops warm air escaping out of the bag.
Hood: An adjustable hood will allow you to close the bag around the face, which is essential in cold weather.
Zip baffle or draft tube: This is a flap which is usually insulated that will cover the zip and stop warm air escaping through it.
Foot box:
Feet and toes crush insulation. To compensate, good quality bags will have a foot box as part of the construction. This also allows for a more natural sleeping position.
Mummy Shape: This means the bag tapers from the shoulders to the feet, meaning there is less air in the bag to be heated so the bag will be warmer than an equivalent rectangular shaped bag.
Zip options: Left handed people will prefer a right handed zip and vice versa. This will also allow two bags to be zipped together if they are left and right handed.
Women specific bags: These are generally shorter and have a bit more room in the hip area. Some may add extra insulation at the feet.