Life of insulation: If you lie on the insulation in your sleeping bag or parka, and then move sideways to turn over, you put shearing force on the insulation. That tears synthetic insulations, and rolls Down into pieces of “string” from which it will never recover. Stuffing your bag or parka does the same thing, plus puts excessive loads on seams. Prior to 1966 we had people bring 2 to 3 year old bags in to restore loft, and we found the lost loft was entirely due to “strings” of Down caused by lying on it. Since 1966 our bags with pads IN them have never had that problem. If you are using a bag loose on a separate pad, put some straps on the bag bottom to hold it securely to the pad, and shift as much of the Down out to sides and top as you can so you won’t lie on it. To pack a bag, always carefully fold and roll it. Uniform end compression of the roll to fit in a sack won’t harm it. Don’t stuff anything you don’t want to rapidly destroy!
Washing and drying Down: A simple test will show that equal dry thickness of Down will dry much faster than synthetics. As Down dries from the surface, interior moisture wicks to the surface where it has access to dry air and heat for rapid evaporation. With synthetics the surface lofts and insulates the interior so it takes much longer to get the needed heat in and the water out. BUT, if you saturate a Down bag and let the Down all clump together, drying will take much longer: you have greatly reduced surface area and greatly increased thickness to be dried. Thus the stories of Down being slow to dry! Those stories are correct when you put them in context. Wool is similar to Down in wicking ability and moisture holding, but being available only in dense heavy woven form it doesn’t compress as it gets wet (it’s already compressed). Both Down and wool can absorb many times their weight, within the fibers, with no effect on insulating ability. Add more than about 5 times their dry weight and Down starts to collapse and lose insulating ability, while air spaces in wool fill up and you lose insulating ability. In each case people get misled, not realizing how close to total collapse their nice Down bag is after 5 or 6 nights without inside vapor barrier, or thinking their wool shirt can continue to keep them warm without rain gear.
A common misconception is that rainy weather means high humidity. Observe how all that dense summer haze disappears after a rain storm. Rain is COLD, formed at cold high altitude, and acts as a dehumidifier as it falls thru lower levels. Where there is regular rain and overcast (as in the NW) the humidity stays low most of the time, and that dry air flowing over the mountains causes desert conditions to the east. In the SE, quick storms soak everything and then intense sun evaporates that water, causing 100% humidity and continuous haze (thus the Smoky mountains).
We often hear of people using short or narrow pads to save weight. When sleeping you need MORE insulation at your feet since you are no longer producing lots of excess heat in your legs and feet as you do when hiking. If your pad isn’t wide enough to support your arms when on your back you won’t be able to stay comfortable and won’t sleep well. It’s good to minimize weight, but you can carry much more if you get a good comfortable night’s sleep.
Polyester fiberfill is usually the lightest practical insulation per inch for clothing. Good Goose Down is much lighter, but weight of extra fabric used in construction usually offsets the reduced insulation weight. Only in the very thick insulation needed for sleeping bags is the great advantage of Goose Down really important. We are regularly told that such and such synthetic fiberfill is “as good as Down and much cheaper”. But when you compare numbers, for same insulation they are ALL much heavier than good Down bags, yet cost as much. Are they lying? Not quite: Poor duck Down can have loft as low as 200 cu.in. per lb. while best fiberfill can have initial loft of 200 to 300. The rub though is that synthetics lose that initial loft rapidly from lying on it and packing it. Thus they can be as good as worst Down when new but never anywhere near as good of quality as good Down.