Sleeping Bags And The Two Types Of Fill – A Guide To Choosing From Goose Down Sleeping Bags And Synthetic Filled Sleeping Bags.
There are two types of mummy bags; down filled bags and synthetic filled mummy bags. These are distinguised by the type of fiber that is used for the fill. The fill is the most vital part of the sleeping bag. It's what prevents you from losing heat. The fill should do a good job of trapping air, providing you with insulation against the cold outside air.
Down Filled Mummy Bags
Down is the most efficient fill for mummy bags, warmth for weight, and traps air better than synthetic bags. This warmth for weight efficiency makes it ideal for backpacking.
Down Filled Mummy Bags compress better than any current synthetics and so are less bulky when packed. When unpacked, a down filled bags fluffs back to its open state more readily and quickly. It also acts almost fluid like as it readily fills up the void compartments of the mummy bags.
Good quality down originates from China. A debate has been made in the past whether white goose down are better than gray goose down but both are good with minor differences.
Down sleeping bags are marked as 600-fill, 700-fill or 800-fill. This is called the fill power. Fill power is the amount of space that one oz of down will occupy.
The bigger the number of fill power means that for the same amount of space, less amount of down is used which makes the sleeping bag lighter. This is accomplished by using fluffier and longer-tendrilled down.
The American Society for Testing and Materials (ASTM) ordained standards for down content and fill power. By law, down must be at least 80 percent down i.e. cluster and fiber rather than quills, beaks, etc.
A good down sleeping bag will bounce back when you poke it with your finger. When properly taken care of, a down filled bag can last for a long time. One spirited hiker I personally know used his for more than 20 quite some time.
But down is not quite perfect. You need to avoid getting it wet or it will stop keeping you warm and you'll have better luck drying mud on a rainy day than drying a down sleeping bag on your trip.
Down is murderously expensive and requires more care in maintenance. In some cases, infrequent as it is, an allergic reaction may occur.
Synthetic Filled Bags
Synthetic fills have been around for quite some time. They come in are distinguisedent name like Primaloft, Thermolite Micro, Hollofil I & II and more. The names tend to change and the producers will likely come up with fancier names.
There are three forms of synthetics characterized by the length of fiber. All the three forms of synthetics can be lubricated with silicon or other liquids to make them feel more silky, more like down.
Even though down is still the best fill for sleeping bags, synthetics are not far behind. Unlike down, they can keep you warm even when wet and they dry more readily.
The biggest advantage, however is that they are a lot cheaper than down and a further improvement will take down into extinction in sleeping bags and even apparel.
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