Waterproofing a down bag

I knew that would get some attention. I didn't want to highjack the thread a few posts down.

Is it possible (or advised) to use one of the (many) spray-on applications on the shell of a down bag to at least make it a little water resistant? Specifically I am speaking of warding off condensation, frost and the drips from opening the rain fly, etc...not exactly waterproofing. I've never owned a down bag, and I'm ignorant.

Regards
Andy

No. at least I wouldn't.

Condensation from the outside isn't much of a problem.

Nope.

And here's why: When you waterproof the shell of a down bag, you increase the possibility that the condensation is going to form INSIDE the bag, in the down. Wet down doesn't do a very good job of keeping you warm, so that's a bad thing.

You can sleep in a bivvy bag, which is more or less waterproof. And then your down bag won't form quite so much condensation on the inside. But it will usually form condensation on the outside...and since the shell isn't waterproof...

This is why tents were invented.

Yeah, before that happened the outdoors was a miserable place. The pity and horror I felt looking down from my hammock on all the poor ground dwellers sleeping in puddles was almost enough to make me stop going out.

I think that the recommendation of a bivy was a great idea. As far as spraying something on the bag I would agree....I wouldn't do that. Just get a good water proof bivy(and there are plenty) and sleep inside that. Just a thought...sabre11004...

I'm going to go against the consensus-so-far (first four replies) and note that the O.P. wasn't really talking about water proofing a down bag, just making it somewhat water resistant --- and that this is very common, bags typically come with some sort of DWR (durable water resistant) finish, sometimes even with water resistant fabrics such as EPIC. In fact, I think it would be hard to find a sleeping bag marketed today that doesn't have some sort of water resistance.

Depending on how the DWR is applied or built-in, it's possible a person might want to renew it, and there are products to do that too. I use a single-wall tent, where condensation can be an issue, so I recently did this with my down bag using a product that you spray on and then put the bag in the dryer to let the heat sort of bake it in/on.

In terms of a bivy sack --- if all you want to do is prevent a little condensation, IMO that's overkill in terms of weight (and cost). And even very breathable bivy's can trap moisture inside, creating exactly the opposite effect you're looking for. I'm sure I'm not alone in the experience of waking to find my bag wetter for the bivy I slept inside than folks just cowboy camping under the stars with no bivy --- this can work either way, depending on the dewpoint, wind, local water sources, how much your body perspires, etc etc.

FWIW, the company that makes the down sleeping bags I own (one with a very fine reputation in the backpacking world), talks about renewing the DWR on their bags; they suggest ReviveX brand spray-on, which is what I used. You can read what they have to say about it here.

Yes, my question was more related to drips and such from inside the tent - condensation shaking off when opening the fly, and general thrashing about. This time last year, I had frost inside the tent that came down in chunks whenever I moved, and thoroughly soaked my old bag. The only cold-weather bag I have is a 0° cabin-type, non-backpacking bag that was not water-repellent in any way. So as I stand here with a can of silicone spray, preparing to douse my old bag, my mind began to wander towards owning a down bag.

Brian, I'm siding with you. I think a lot of "condensation" problems with down bags is due to a general lack of awareness about how to use and handle down. Its easy to find fault, harder to gain the experience to avoid problems.

Basically Andy's question was this
1) can a breathable non-water proof bag be made significantly more waterproof by spraying a DWR on it, and would that help in a tent from occasional splashes - well sort of maybe. I think its worth a try. To those who say it will have more condensation problems after application of a DWR, I say BS... a bivy will have far worse condensation.

2) Is it a good idea to have a sort of water proof shell on a down bag inside a tent? - I say yes, others say no. Personally I do not have condensation problems with my down where I go and how I use it. Also goretex works perfectly for me and I have 30 year old goretex jackets that work nearly as good as new, and I have a goretex bag and a [I think its drylight] bag, and I love both of them.

soap box on:

HOWEVER question "common sense" and "camping trends" because they rarely are based on deep experience, but rather on first order physics. For instance people will say titanium pots are poor conductors because titanium has a lower conductivity coefficient, but what they totally ignore is the laws of thermodynamics and don't realise they must divide the coefficient by the thickness, and titanium is made thinner and actually titanium pots conduct better than thicker steel ones. If you set a stainless steel pot and a titanium pot same size on snow and pour boiling water in them, the water in the titanium pot will cool much more quickly.

I mean the condensation arguement completely ignores that water is a three phased material that can pass directly from any phase to any other. Ice can evaporate without first melting, and vapor can freeze without first liquifying.

and finally - Some of the most experienced influential outdoorsmen are total crackpots.

soapbox off

Jim

Making a down bag totally waterproof for temps above 0F is a mistake. If you do get condensation in a bag with a waterproof shell it will be from your perspiration, and then you will need a few hours of sunshine on the breathable liner.

What kind of tent are you using? Does it ventilate?

I really did not mean to make it such a difficult question. We occasionally will have a family "camporee" in late fall, in farm country where it is perfectly flat, no trees or windbreaks and on a clear night with no wind all the ground heat quickly radiates away. When there is no breeze at all, campfire smokes rises straight up 50-60 feet and it is almost eerily calm. Everyone gets a heavy coat of frost inside and out. I have a mesh tent with a fly, the fly will be covered inside and out and on a few occasions the mesh as well. Then when you move around, big sheets of frost will plop down on you and instantly melt. So I was asking not about waterproofing, but if it was possible to add some water-resistance to make the water bead up and roll off.

I don't even have a down bag. But every sentence where somebody writes about down, they also say "don't get it wet". Well, how wet is wet? Throwing it in the creek, sure. Slop a little water on it while getting a drink? Dew? A little rain comes in when you're making a potty dash? This sort of thing.

Yep. that's wet.

Not really

Could be, but a few drips from condensation, not really


Generally no. particularly if you dry it out during the day or at night.

I've gotten dew/frost/etc on my bags and not had much ill effect. I get them wet when I breathe on them in the winter. Generally it's just the shell. a wipe off and a layout is fine.

Down bags don't dissolve at the first sign of moisture.

Do I make sure I air out the bag and give it an opportunity to dry moisture off the shell? yes at every opportunity.

If you've ever tried to wash a down item in a tub of water, it's actually pretty hard to get it soaking wet.

Ventilation isn't about wind, exactly. It sounds like your campsite is in an area that sets you up for the condensation.

I would get a driducks poncho and drape it over the bag.