Compression damage to down Sleeping Bags

[Richard Fraser]

I've been thinking of getting a new sleeping bag and going for a down bag. My main reason is that warmth for weight and volume seems generally much better than their synthetic counterparts. I'm wondering however if compressing a bag down as much as possible in a compression sac could potentially damage the down filling reducing its effectiveness. Is this a valid issue of concern or should I worry more about the down bag getting wet story?
Cheers
Richard

[CW]

Over compressing any bag, whether it be down or synthetic, will eventually lead to loft degradation. I personally don't use any compression sack or even stuff sacks for my insulation (certain conditions excepted). My quilt or bag goes in the bottom of my pack (inside my liner) and gets compressed as necessary to fill up the pack.

[Travis Leanna]

I don't use compression sacks either. I do use a stuff sack that keeps my bag nice and small, but not one that I have to have three full grown men help get it in there. Generally, I find that manufacturers stuff sacks are a tad small.

[drowning in spam]

A compression sack might not save you much space due to the hard shape that can create wasted air pockets at the corners and edges. I use a stuff sack for moisture and cut protection. Keeping it loose allows it to fill the little nooks and crannies in your pack.

But yes, you can damage anything if you try too hard to compress it, including down.

[Richard Fraser]

Thanks for the quick replies guys :)
I guess this is going to be harder than I thought, searching for the ultimate compromise between volume, weight and warmth.
Do you know of a comparison between packed sizes of sleeping bags?
Thanks once again
Richard

[Philip Maynard]

Does anyone have anything to back up those statements? I called Western Mountaineering and they said I can compress their bags like rocks with no long-term damage. They said it's the stiffer feather components that are damaged by compression, wheras down content nestles together and compacts neatly, without crunching or folding anything.

They did say it will take longer to loft, meaning a colder night if it's too compressed. But, get home and toss it in the dryer and it'll be 100% again.

So, their recommendation was to compress it only as much as necessary, but that was to stay warm that night, not to keep the down from being damaged.

Also note that there's a big difference between using a stuff sack, using a compression sack, and standing on a compression sack while using hydraulics to crank it down to a stone. I have a -10ºF bag from Western Mountaineering, and it takes up my entire pack when fit into the WM stuff sack. A Granite Gear Air Bloc Solid stuff sack compresses it another 50% or so, but it is far from being a rock, and lofts up fully every night when I pull it out.

I also find the GG sack's square shape packs better, filling out the corners of my bag. It's also quite waterproof.

In my experience down is nearly half the size of synthetic when stuffed comfortably into a sack. However, synthetics ARE damaged by being compressed, whereas you still have room to move with down. Note that the fabric portion of the bag along with the zipper takes up a lot of space, so a 40 degree synthetic bag might be very close to the size of a 40 degree down bag, due to the shell dominating. However with a -40º bag down compresses into a manageable size, while synthetic bags are just enormous. To make this more amazing, realize that for a given amount of warmth, synthetics have a much thinner lofted size, usually around half the thickness of down!

Keeping down dry is a red herring. Certainly take care to keep your insulation dry no matter what kind it is, but don't let that affect your decision.

In general, down bags are higher quality and more expensive, offering more choices in shell fabrics. You can get nice Rab bags with Neutrino Endurance shells that are nearly waterproof which is what I use instead of a bivy when sleeping in a tarp in wet and windy weather. Few if any synthetic bags offer such an option.

[Ike Mouser]

stuffing in your pack will be fine, and you will not have to carry those heavy stuff sacks. Weight adds up there quick when you realize you have stuff sacks for this, compression sacks for that, dry sacks for this, etc.

[Mike M]

I posed this very question last year, Tim Marshall (Enlightened Equipment) among others, said no worry on compression damage. If WM said the same thing, I believe it's a non-issue. I will add they are talking about short term compression- obviously the bag should be stored loose in a large bag for longer storage

[Joe Clement]

I'm surprised by Philip's discussion with WM. I could have sworn that there was a statement on the web site, or in the supplied instructions, to never use a stuff sack smaller than the one provided by WM. Maybe not.

[Greg Mihalik]

Posted somewhere on this site was the first-hand report of a down bag stuffed tight and lost under the bed for 3 years…

… and after a bit of fluffing, lofted like new.

YMMV

Also, a granite gear Air Reduction Block with the eVent bottom will keep your bag dry under all circumstances, as well as conform to any available space in the bottom of your pack – no "void volumes" to contend with.

[D G]

Sometimes if the bag is old and the down is dirty/contaminated with body oils etc it can loose it's loft, especially after compression.

I heard a podcast a few years ago where the owner of Western Mountaineering was interviewed. There where many instances where an old, flat bag with no loft was returned to them and he said that they just washed the bag and it was restored to full loft and returned to the owner.

[drowning in spam]

Let's look at this a different way. Instead all the weight of a sturdy compression sack with its buckles and straps you could put that weight towards a slightly larger pack. As a bonus you get a pack that's easier to pack and saves you time in camp.

The only reason I would want to stuff a bag supertight is if I was trying to camp in a place where camping is not allowed, which means I'd want my pack to be the size of a daypack. Of course the pad would go inside and be inflatable.

[John Nausieda]

For WIW my Sierra Designs Mist came with a compression sack standard. This bag is rated as 0-15 degrees and lofts like crazy. I use a large Granite Gear airvent compression sack which is very light using cord pulls instead of straps. I lay on it to compress the bag-otherwise the cords are hard on your fingers. The bag ends up being a semi-rectangular package which totally fills an outdoor research Dry Peak Bagger which is strapped to a Mountainsmith Ghost. I do lots of day hiking after setting up a base camp. This way I have the equivalent of 2 dry bags covering my down even though it's outside the main pack. I wouldn't be able to use this set up without the compression sack.

[Richard Fraser]

Thanks for all the differing views :)
I know there not going to ever be a definitive answer that will cover all situations. I'm NOT an ultra-light trekker, I may become one but I don't think I'm ready to go that extreme yet. I've pretty much settled for a Karrimor SF Sabre 45 Lt + two detachable side pockets (12.5 Lt each).I have been advised to go for something more like the Golite Jam but I think the flexibility of the Karrimor system will suite my needs better.
The above is the reason I want to find a bag that is both warm, light, and compressible. I'm also impressed with the water resistant qualities of the Rab bags with Neutrino Endurance.
So my criteria are that it fits within my carrying system, keeps me warm and can be protected against what nature can throw at it in the UK.
I'm also intrigued with the self inflating down mats. These look great and if it takes the same (=/- not much) volume and weight as my current Vango mat then its a winner. Is this also the reason why I seen offers of high quality quilts here and on a few other sites. I've never heard of anybody using a quilt for trekking before but in combo with a down mat I can begin to see its possibilities.
Lots to ponder
:)
Richard

[James Klein]

I agree with most here…loose stuffing tends to be more effiecent for volume and wieght than compression stuffing.

WRT to compression damage…with a down bag I would be more worried about damaging a baffle than damaging the down cluster when compression stuffing.

Most reports, surveys and the like I have read indicate the down loft is relatively unaffected by overstuffing (esp. compared to other factors affecting loft like oil/dirt).

Also, if you were worried about compression damage I would stay away from synthetic, as it is probably much more prone to stuffing damage.

[drowning in spam]

The above is the reason I want to find a bag that is both warm, light, and compressible. I'm also impressed with the water resistant qualities of the Rab bags with Neutrino Endurance.
So my criteria are that it fits within my carrying system, keeps me warm and can be protected against what nature can throw at it in the UK.
I'm also intrigued with the self inflating down mats. These look great and if it takes the same (=/- not much) volume and weight as my current Vango mat then its a winner. Is this also the reason why I seen offers of high quality quilts here and on a few other sites. I've never heard of anybody using a quilt for trekking before but in combo with a down mat I can begin to see its possibilities.

A quilt can totally get rid of part of a sleeping bag as well as a long zipper, so it weighs less and takes up less space. Taking up less space also means a smaller lighter pack can be used. Double weight savings.

If you want the ultimate in warmth, lightness and compressibility, along with water resistance, then you want to contact Tim Marshall about getting a cuben fiber down quilt made for you. You could get a 0° F quilt that weighs less than 20 ounces. That was part of a gear list that allowed me to pack 11 days of food at 4500 calories a day, a down jacket, a fleece jacket, 5 liters of water, a tarp and a bivy into the main compartment of a ULA Catalyst with room to spare.

[Bob Gross]

It has been my experience that excess compression does not really cause any permanent damage, unless you leave it stuffed for a long period of time. If you stuff a bag in the morning, carry it all day, and then pull it out in the evening, a certain amount of fluffing will get the necessary result. If you stuff the same bag and leave it that way for two weeks, you will pay a penalty. If you leave it for six months, you will pay a larger penalty.

–B.G.–

[Mary D]

As are many others, I'm rather paranoid about my Western Mountaineering Ultralight bag due to the $$$ invested! I keep having to remind myself of the information posted above. However, you really can damage high-quality down by leaving it stuffed for long periods, especially when it's damp. Always get it out and air it out right away after a trip. I use my clothes dryer on low for just a few minutes, but it will puff up just as well–maybe better–outdoors in the sun or indoors in a heated room. Store the bag very loosely, in the big breathable storage bag (which should have come with it), or under the bed or hanging in the closet.

If you use a waterproof pack liner, just shove the sleeping bag into the bottom of your lined pack without a stuff sack and put the rest of your stuff in on top. I prefer to use a dry bag for my sleeping bag instead of a pack liner, but I don't stuff the bag very hard–I want the results squashy rather than rock-hard. Stuff sacks are not waterproof (even if the material is, the closure isn't) so won't keep your sleeping bag dry anyway; they therefore add unnecessary weight with no protection. You will never need a compression sack for a down sleeping bag–the down bag will take up no more than 1/2 to (at the very most) 2/3 the space of a heavily compressed synthetic bag.

[. .]

The key is keeping the bag dry and clean while storing, whether stuffed or not – but especially when stuffed.

[Philip Maynard]

Thank you for reminding me of that part of my conversation with WM: they said not to compress it any more than I had to when wet, as that could cause issues. They cited people sticking their heads in their bags and soaking the hood from condensed breath as an issue.

[Paul McLaughlin]

I'm in the big stuffsack camp – I like the way a big stuffsack fills any nooks and crannies, plus I find it's just easier – especially in cold weather. I've been through the pleasure of trying to get a sleeping bag into a tight stuffsack with cold hands and I'll skip that next time, thanks. Plus a compression sack is so much heavier than a simple stuffsack.
One word on long-term storage – maybe the best reason to store your bag loose is to ensure that it can dry out thoroughly. Keeping a completely dry down bag compressed for a long period may do no harm, but keeping a damp down bag compressed (and a down bag is generally slightly damp at the end of a trip) will.

[Mike W]

…

[Franco Darioli]

This may help a bit.

I have had these two bags for about 15 years and were purchased used. They have been washed at least 3 times.
The one on the left has been kept inside a loose mesh bag, the one on the right was compressed inside the stuff sack for most of two years.
It has been out of that sack for a few days now and fluffed up by shaking it.
At first after a few shakes it was still a bit flat however it has regained most if not all of the loft.
It is probably 600 loft down however I cannot feel any "feathers" inside.
Franco

[Jim Morrison]

Franco;  that seems like a good comparison and sort of the “proof of the pudding” you might say.  My issue is that I would like to keep a top insulation (jacket) stuffed in my pack so it is ready to go quickly.  I might get a call and need to get packed up and go quickly. I didn’t want to keep my nice new down hoodie jacket stuffed because I thought it might get damaged.  My solution nowadays is to just lay it on top of my pack and stuff it when I get to the trailhead.

[HkNewman]

My down quilt has been good for many many outside nights doing long sections of the long trails so figure about 300, and I worried as sometimes I’ll forget to unpack it for up to a week.

So I car-camped where the low was forecast at my quilts’ advertised rating a few weeks ago, ..double checking with thermometers in the pre-dawn cold.   This is where humidity was low.  Works like new when dry (I have dedicated sleep layers that double as storm baselayers).

Inadvertently used it next to a stream bed the next weeks trip, and the humidity made it colder as should be expected.

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