Why isn't down waterproof?

[Doughnut]

I had time to ponder (never a good thing!) and got to wondering: geese and ducks don't get wet, so why is down not waterproof? I assume it's because the oils are removed during a process, but that's just my assumption. Anyone know?
Thanks,
DoughNut

[Feral Bill]

On the bird, the down is covered by water resistant feathers. Ask any goose.

[Desert Reprobate]

Yeah, the ones without the waterproof outer feathers drowned a long time ago

[ColdFire]

It's because the Goose is removed during the process..

[Manwich]

There are Feathers and Down. The Down is protected by the feathers, which are waterproof.

[wrongway_08]

If they coat the down in a water proof treatment, it looses the ability to retain heat and loft, when crushed it would stick and not loft again. When washed it would get ruined by the coating they put on it to keep it water proof.

So untill something new comes along that will work with the down to retain loft ... you just got to keep it dry or use a water proof fabric to hold it in.

[wrongway_08]

On the duck or goose, the skin makes an oil that keeps the feathers/down water proof. When you see ducks and geese fluffing their feathers, they are recoating them with the oils. This is how they seem "water proof".

The feathers are thicker and are used as a wind break and rain water deflector. The down is also coated in oils but is there to retain heat and keep the bird warm.

[Compass]

I am not an expert but I would bet that the placement/orientation of the down when it is attached to the bird would help the water roll off. Once it is all mixed up it unfortunatly traps water but still holds heat. IMHO

[Ox97GaMe]

It is a combination of several things.

a) feathers cover the layer of down.
b) oil on the feathers makes them more water repellant
c) feathers are stacked/overlapping, sort of like shingles so as to keep water from penetrating multiple layers.

When down is placed in a bag or jacket, it is in a haphazard manner. There is no oil or other 'waterproof' substance added to it. Therefore, down in a bag and down on a duck do not portray the same characteristics.

Same would be true if you threw several shingles in the yard. They would not be very waterproof either, although they are if you properly install them on the roof.

[Wise Old Owl]

On the duck or goose, the skin makes an oil that keeps the feathers/down water proof. When you see ducks and geese fluffing their feathers, they are recoating them with the oils. This is how they seem "water proof".

The feathers are thicker and are used as a wind break and rain water deflector. The down is also coated in oils but is there to retain heat and keep the bird warm.

I agree it's called preening, the duck is moving the UL oils around with its beak to make itself "clean"

[Jayboflavin04]

There are SOME natural oils in the down. This is why you wanna be careful when laundering your down bag. U dont want to use a typical detergent as they are too harsh and will strip these oils.

Has anyone seriously gotten their down bag soaked on a trip....rendering it useless. I hear that it is really kinda hard to soak your down bag. Because of the tight weave of the fabrics and the water treatment on the outter fabric.

I always try to keep in mind "nothing is waterproof" when it comes to backpacking.

[4eyedbuzzard]

My understanding is that when down is commercially processed prior to use in sleeping bags, pillows, etc, it is thoroughly washed before it is sorted (by weight/fill power) and the natural oils are removed. If the oils were left in it wouldn't loft properly. That's why as it gets dirty with dirt, oils, and our own body oils it starts to lose its fill power.

[saimyoji]

So untill something new comes along that will work with the down to retain loft ... you just got to keep it dry or use a water proof fabric to hold it in.

aerogels

http://en.wikipedia.org/wiki/Aerogel

[Alligator]

It's because the Goose is removed during the process..

Very true.

[sheepdog]

I agree it's called preening, the duck is moving the UL oils around with its beak to make itself "clean"

An Owl should know a duck doesn't have a beak
A duck walks into a store and says "give me some chapstick." The clerk says "will that be cash or charge?" The duck says "put it on my bill"