The outer material must be lightweight, windproof, waterproof and breathable.
The inner material must be light and hypoallergenic, the most used are polyamide and polyester absorb little moisture and dry quickly, and unlike cotton can not rot. They get less dirty and absorb less odours so it is not necessary to wash them often, extending their life.
Which padding to choose for my sleeping bag?
There are two different types of padding: feather/down and synthetic.
- Feather/down jacket
- Feather, Duvet
The feather/down jacket is still today the most used material both for the best sensation (of course it is subjective), both for its reduced dimensions in relation to the comfort temperature, and for its great compression capacity. The padding can be made with feathers or down.
The feather (left) is less valuable and less performing in terms of heat retention, the down (right) is more valuable, has a better thermal capacity and greater compressibility. Today many sleeping bags contain both elements in different percentages (if you find the wording down 90/10 it means that 90% is made up of down and 10% down). The defects of this padding are the high price and the almost total loss of wet insulation capacity.
The synthetic padding is made of a highly effective material and has excellent standards of temperature and comfort. These ultra-thin hollow fibres are technological and have excellent insulating properties even in wet conditions.
But this fibre is heavier than feather/down and has a limited compression capacity. This padding is less resistant to compression and decompression cycles (compared to down), which reduces its ability to expand and thus retain heat.
If you are looking for a small sleeping bag, with a good thermal capacity and a reduced weight, the feather is the ideal solution, while in humid climates is better a synthetic padding, which even when wet keeps the same warm and dries more quickly.
You also need to keep in mind the moisture produced by the body through sweating and evaporation even in restful situations, which can change the performance of the sleeping bag. For this reason it is very important that the inner lining is hydrophobic (does not retain water).
The shape of the sleeping bag
The shape of the sleeping bag can be mummy or covered.
The mummy shape (A) is recommended for cold climates, because its reduced surface allows the body to heat better and faster the ‘inside of the sleeping bag which is equipped with a collar and hood for the head that allows to avoid unnecessary heat loss.
The deck or square shape (B – C) is recommended for hot climates and has a much larger internal surface that allows better mobility and comfort, obviously have a larger footprint when closed. This type of sleeping bag can be without collars and hoods or be equipped with them.
What is the Thermal Coefficient?
On almost all sleeping bags are indicated the temperature of use that are regulated by European law DIN EN13537 is good to check that there is the writing, the number of the law to be sure that the manufacturer does not write wrong information. I also recommend reading the instructions given by the manufacturer to better understand the parameters indicated.
The indications are:
- Maximum temperature is the one that allows a standard man a continuous sleep without sweating abundantly with the sleeping bag open and arms out.
- Comfort temperature is the temperature that allows a woman of standard weight and body to sleep for a whole night in a relaxed position at the lowest temperature indicated.
- Limit temperature is the temperature that allows a man of standard weight and stature to sleep all night without interruption in a cuddled position (this posture is assumed to minimize heat loss) without feelings of cold (usually are about 5 ° C less than the temperature of comfort).
- Extreme temperature is given by the lower external temperature in which the sleeping bag protects the user (standard woman) from hypothermia (but with symptoms and freezing at the extremities) and manages to have 6 hours of sleep curled up not comfortable and not continued.
When I write standard woman or man I refer to a subject of average weight and height, they are not superman, trained people or survival experts, but not even sick elderly people. And keep in mind that they are measured temperatures without the addition of clothing, so the clothes you wear when you use the sleeping bag lower the limit of it (helping to preserve heat).The type of shelter is not calculated either, if you sleep in a tent or bivouac these will help to lower the limit. when you choose a sleeping bag you must choose it according to the temperature of comfort, obviously the feelings of heat and cold are subjective and there are several factors that affect the performance of the sleeping bag.
What are the factors that affect the feeling of haste?
- The metabolism is different in each of us and the sensitivity to cold varies
- Age, older people usually have a generally slower metabolism and therefore take longer to produce heat.
- Body weight, fat people can draw on their reserves to increase their body temperature, and the fat itself acts as a thermal insulator.
- Sex, women have a higher perception of cold than men, about 5°C more.
- Habits, who is accustomed to living in very warm homes suffers more cold than who is accustomed to lower temperatures.
- The experience that leads to better know the equipment and your body managing to make the most of both.
- The level of psychological health, in fact, who is under strong emotional stress has a higher perception of cold.
- The level of preparation and physical health, both the training of the body and the level of fatigue, in fact an exhausted body produces less heat than a rested body.
- External humidity, you should always try to stay as dry as possible trying not to wet the equipment and not to sweat too much.
- The presence of wind that can lower the perceived temperature by several degrees.
- The diet, if we eat little our body does not have enough carburetors to burn to keep us warm also must always keep hydrated.
The different characteristics
The characteristics of a sleeping bag can positively affect its ability to keep you warm, such as a good hood, is the one that wraps around your head well but that leaves your face uncovered to allow you to breathe. The collar is very important because it holds the heat inside the bag.
The long zippers allow you to enter and exit comfortably and to let out the excess heat and have good ventilation, the short ones are used to save weight, volume to reduce heat loss at the expense of ventilation.
The size of the sleeping bag is very important because if it is too large it allows more air to pass through than necessary, it keeps less heat and weighs more.
If it is too small, you will be forced to crouch down and compress the padding to make it cooler.
To be able to choose it, you need to know what is written above and try to understand what your needs are and in what area the sleeping bag will be used.a good sleeping bag must be suitable for your body, it must retain the heat released from the body, it must be light and compressible. After buying the sleeping bag you must take care of it and I recommend reading the article “How to use the sleeping bag”.