When I bought my first down sleeping bag, I really didn't know what I was looking for. I simply picked what looked the warmest, felt the softest and...cost the most. Sure, the guy selling me bag answered some of my questions, but how much did he really know?
What does Down mean and what should you consider when purchasing a down sleeping bag?
Down consists of clusters of the light, fluffy undercoating that geese, ducks and other water birds use to keep warm. Unlike feathers, down has no quill shaft, instead growing from a central quill point. Down is a three-dimensional structure, and can expand in all directions. Because of this down can capture thousands of tiny air-pockets making it an excellent insulator.
Down is measured in both it's Fill Quality and Fill Rating or Loft.
Generally the best down comes from more mature birds and as a general rule goose down is of a higher quality than duck down. The down from younger birds tends to be more fragile than that from older birds and will not bounce back as well if crushed.
Both ducks and geese have way more feathers than they do down, so getting a 100% down bag is rare. Infact, alot of down can contain up to 30% of chopped up feathers. You should look to see what the mix of down to feathers is. You should also look to see what percentage of the down is goose and what is duck.
Other attributes which affect Quality include; Density (how close the fibres are at the centre); Cling (how much the down fibres stick to one another); and Breathability (how much moisture the down will wick away). Density and Cling will affect the insulating abilities of the down, while Breathability will reduce the clamminess often associated with synthetic fill.
Loft is directly related to the insulating attributes of the down. Loft is determined by measuring the expansion of one ounce of down in a standardised Plexiglas cylinder under controlled conditions. A specific weight is placed on top of the sample to simulate the load that the covering fabric will exert on the down. The higher the Fill Rating the greater the warmth for it's weight. Additionally, high Fill Rating comes from more mature birds and hence will tend to last longer.
Important: Fill Rating or Loft has no legal standing. The loft measurement is an informal agreement between suppliers and retailers. As there is no legal enforcement you should consider whether any independent testing has been completed. In the event that you cannot determine this, you will need to rely on the reputation of the manufacturer when making your purchase.
Some people sleep cold, others move around alot in their sleep and others still just want to increase the insulating capacity of their sleeping bag. For this reason, manufacturers will sometimes offer an overfill option. Additional down is added to the bag and will generally reduce the temperature rating by 5F or 2-3C. Bags with an overfill will normally be shown with a + after the Loft Rating (eg 800+).
Most high quality down sleeping bags will use geese down over duck down. Most commercial down comes from ducklings, meaning the down is more likely to be fuzzy and not as dense as the down which comes from older geese. Down from older ducks also tends to cling to the feathers during the processing stage resulting in a higher amount of feather being mixed into the down. In reality, down is often a mix of both duck and geese down. You should look to see what the makeup of the mix is.
Benefits of Down
- Down is up to four times as thermally efficient as synthetic materials
- Down is very light
- Down can be compressed very tightly and still spring back into shape
- A well looked after down bag will last many years
Disadvantages of Down
- Down costs alot more than synthetic materials
- Down loses it's insulating benefits if it gets wet and takes a long time to dry
- Down will compress when you lie on it, exposing you to the cold ground
- Down can clump, leaving poorly insulated spots
- If you tear your down bag the down will fly everywhere
Things to remember
2 bags of the same weight, higher Loft = warmer
Other things to think about
- Shape of the bag: (this will affect how much air can move around in the bag and also how much you can move around in the bag).
- Size of the bag: (the last thing you want is to have bag which only reaches your armpits. At the same time a bag which is too long will allow too much air to move around in the bag).
- Temperature Rating: (manufactures will generally provide a temperature rating for a bag. This will include both a Comfort Rating and a Survival Rating. There is no standardised rating system for all manufactures so it's often difficult to compare bags from different manufactures).
- Hood: (most body heat is lost through your head, so consider whether you want a hood).
- Zippers:(when your freezing cold, trying to pull on a tiny zipper may be a little frustrating. Consider larger, sturdy zippers).
Picking a down sleeping bag isn't as simple as grabbing the one with the best colour scheme. There are a lot of things to consider and down bags really are designed for specific reasons. A bag with an 800 Loft rating is going to have you sweating like a pig on a warm night. While a poorly designed bag may have you freezing on a cold winters night. While I'm never a fan of paying more than I need to, when it comes to Down, price usually does translate to quality. As a general rule, if two bags have the same weight the bag with the higher Loft will be warmer. Of course, the difficulty comes when trying to compare different weights and different Loft (for example, 700 grams of 600 Loft versus 600 grams of 800 Loft).
All the above rules can be applied to any Down items, including Sleeping Bags, Jackets and Gloves.
And remember, always stored you down items hanging up and in a dry place. This will provide many years of enjoyment.
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