Caring for Down
There are other general topics which need to be covered to give a more complete picture about down.
The one major criticism of down is its poor performance when wet and there's no denying that it can lose up to 90% of its insulation value when soaked through. The responses to this vulnerable point are; don't get it wet, use a proofed outer material, waterproof the down itself.
'Don't get it wet'
For many people this works fine. Cold conditions present less problems and care can avoid most other potential soakings - but not all. An overflowing stream, a poor tent, even a long stay in very humid conditions with heavy condensation, and you may have a wet bag. In those circumstances a synthetic bag would be performing better, but so might the right down bag.
PHD's Drishell outer fabric is waterproof, highly breathable and very light. We think this is the best way at present to tackle the problem. However proofed outers are not perfect. Bags made with Drishell and similar fabrics do carry a small weight penalty (Drishell is the lightest we know of this type), and they do let water in at the stitch line (e.g. if you are sleeping in a puddle). Bags can also be made with complete taped outer shells (we offer this option), which will be proof against nearly all situations, but the weight penalty of an extra skin is considerable.
The only remaining alternative is to waterproof the down itself. Methods for doing this have been around for years, all making substantial claims about improved performance in wet conditions. We test this kind of material ourselves at regular intervals for 3 simple criteria:
- Does the down wet out more slowly?
- Does it absorb less water when fully wet (weight gain)?
- Does it dry more quickly (left to dry without applied heat, as in a true 'field' situation)?
Right up to the present we have found no measurable difference between treated and ordinary untreated down.
The fillpower test gives a measure of the loft of the down tested at that moment, nearly always new down. It gives no indication of how long any particular down will hold that performance or of how quickly it will deteriorate. The only method of assessing long-term performance lies in the experience and skill of both supplier and manufacturer. As before processing can affect the future life of the down as much as the raw material itself and experienced eyes know what to look for in a new down.
The criteria which ensure longevity differ a little from those which produce good results in the first fillpower test. For example cluster size: I have seen downs composed of small clusters, which only afforded average - good results when new, still giving undiminished performance after more than twenty years of regular use, several washes and continual stuff-sac storage - while other downs with larger clusters have deteriorated much more quickly. However these are not scientific tests - no two bags get identical usage over a period of years and deliberately storing bags under compression bears no resemblance to the hard treatment of real use.
Overall this may appear a discouraging point: you can buy a bag with good down in it, but with no guarantee of how long it will last. That is true enough, but the factor most likely to degrade your down bag is your usage of it - how often, how dirty and wet the conditions, how you care for it, store it, etc. Read about cleaning and washing down. Console yourself with the thought that even downs with a comparatively 'short' life are likely to last 3 times as long as a synthetic equivalent, and a down with long life . . . well, you may give up the sport first!
Bag design and construction
The whole point of high quality down is to provide warmth for the least weight (otherwise you might as well use feathers - much cheaper and just as warm if you put enough in). To maximise the effectiveness of the finest fill requires good design. Down with the highest fillpower in the world will not provide the best weight/warmth package if the shell uses inferior materials or poor construction. And such is the price of the best downs that they are an expensive folly unless matched by design and craftsmanship of an equally high order.
PHD's bag design is covered in this article, but it is worth remembering that high fillpower figures by themselves are only the start of a superior bag.