The upholstery of sleeping bags does not produce heat, but reduces heat loss of the body during sleep; sleeping bags can be produced with a synthetic fibre insulation or feathers.
The synthetic fibers are preferred in cases of wet/rainy weather conditions long trips where there is a risk that your sleeping bag to get wet and have no chance to spread it out to dry. On the other hand, however, synthetic fibers make the sleeping bag heavier, bulkier (because less compressible) and less comfortable than feathers.
Feathers in fact guarantee more heat in relation to their weight; the sleeping bag stuffed full of light weight feathers takes up less space and is also more durable, maintaining almost unchanged its softness. It should be noted though that sleeping bags with this type of padding are more expensive and that water is the biggest enemy of feathers: when the feathers get wet lose their softness and their ability of thermal insulation. If you decide to buy a sleeping bag with feather padding is important, so you make sure not to expose it to water, even if you recently launched some sleeping bags filled with waterproof feathers: in these products the feathers are treated with hydrophobic substances that block the filter a small amount of water (of course if you soak in a storm even these treated feathers get wet). In addition to known aversion to water, there is also another element that drives consumers to opt for a synthetic, or ethical issues associated with feather padding (it is believed that the process used to derive the feathers is extremely painful for animals), which direct the vegans and animal rights activists to advise against buying these products.
You must also keep in mind that there are different types of feathers, which are distinguished by their quality: goose feathers are those that are considered the best ever, but having become rarer are much more expensive.
To summarize it all, choose the padding suits you carefully evaluating all the factors:
- The climate. If you cross the rainy/humid climates or multiple locations with different climates you should opt for a synthetic fur;
- The weight. Synthetic fibers are generally heavier and less compressible feathers.
- The cost. The feathers are more expensive than synthetic fibres.
- The longevity of the product. With the passing of time and the continuous compressions synthetics break and thus reduces their ability to conserve heat. From this point of view the feathers last longer.
- Maintenance. The feathers are more delicate and for this more careful maintenance and is made with specific products; Unlike synthetic fibers can be washed safely machine washed using detergents.
Fabric and shape
Normally the sleeping bag tent is used so there is a risk of tearing or ruin; more than tough, then, the fabric of the sleeping bag should be light. Sleeping bags with better quality lightweight synthetic fabric can be recognised, which makes the product less heavy and more comfortable. If you purchase a sleeping bag for winter climates, make sure that the fabric is waterproof/breathableso will keep the inside of the sleeping bag dry even if the tent there is a bit of moisture.
As regards the shape instead, there are essentially two: to Mummy or rectangular. In sleeping bags Mummy shaped the interior space is smaller because it fits the body; This means that if even more uncomfortable because it allows less freedom of movement at the same time reduces heat loss and thus is preferable in colder climates. Also another advantage of mummy sleeping bag is lighter than rectangular ones; the latter are more similar to a blanket and are recommended to targets with mild climate. I recommend, if you get the chance, try the sleeping bag to verify the measures, which are also very important: a sleeping bag too wide holds less hot than a narrower, but at the same time lets in cold climates to guard inside your technological devices, a bottle of water, etc.