How Bad is Sleeping Bag Compression?

I can't be the only one wondering! Anyone that compresses a bag regularly that can chime in on warmth?

How hard are you compressing it?

My Caribou Mountaineering (remember them?) had 1st gen. Primaloft fill.
After just ONE summer of backpacking (about 25 days) the Primaloft bacame just "Prima" with no more loft. And this was with good storage by hanging the bag.

Perhaps by now the newer iterations of Primaloft are better at resisting repeated compressions but I'm not going to try it again.

My Mt'n. Hardware -20 F. winter bag uses Polarguard Delta (hollow triangular fibers) which seems to maintain decent loft. BUT… it does not compress well and is HEAVY!

However Climashield appears to be the best current synthetic fill at retaining loft after repeated compression but still having decent compressability. Climashield would be my choice if I ever buy another synthetic bag.

P.S.
Most likely, given the new down DWR treatments now emerging, I'll hold off a year or two and get one of those for a winter bag. Got to see how each kind of down DWR shakes out in field use. Let others be "early adopters" and discover the best one.

The good thing coming out of down DWRs appears to be that most of them actually increase the down's loft. This bodes well for retaining loft over time.

Max, remember that sleeping bags were designed to be repeatedly compressed for carrying and lofted for sleeping… so I think you're being unduly worried about its performance, given what it was designed to do! I think the whole anti-compression thing is more about not storing it compressed for years, and then expecting it to achieve full lofting power.

Frankly, this would be a good question to ask MH's Customer Service folks, if you really want to know how extensively they tested the exact bag you have…

Let us know what/if they get back to you.

I have a 5 ounce Apex bag I've used for maybe 50 nights – so 50 cycles of stuffing into my pack. I tried not to compress it too tightly.

I just measured the loft at 1.125 inches.

I measured the loft of new 5 oz Apex at 1.4 inches, so it lost 20% of it's loft.

It's R value probably dropped about the same percentage.

Valerie, I'd agree with you except that for me, "regular compression" could be nightly for months and months. Long trips. I sleep in my sleeping bag about 50% of the nights that the weather is in the temperature range. Every weekend and a lot of weekdays.

I'll be putting it through a gauntlet that may well push it past the acceptable limit. I should probably email MH.

Ultimately, when I'm backpacking it's lofty in my pack and when I'm casually touring it's lofty in my large pannier. If I was bikepacking, I'd have to compress it (not to an extreme, but pretty tight) to reduce the volume and keep it balanced on the bike.

Jerry,

Thanks, that's the kind of data I'm looking for.

This thread has some info on the fill in a MHW bag: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=76982

but, two things:

1. I don't think this conversation necessarily needs to focus on my bag. I'm interested in other synthetics and down, too.

2. The ultimate compression rebound question is still unanswered….

I've been using an old NF Hot Tamale for quit some time now. Being left compressed has never hurt it. It does take time to regain loft, but it does regain it. If I can leave it loose in the pack, it has more loft at night, likewise the second day in camp, it has regained most in not all of it's loft.

Hi Max,

I have stumbled across some papers on this question in years past, but the general consensus is that repeated daily compression and expansion of a down bag won't affect it's loft for years. This is also contingent on the environmental conditions you are in, as much as anything else. Furthermore, it would take a substantial amount of compression to "damage" the down in the sleeping bag.

Regardless, I can't find the "smoking gun" article right now, but here are two articles I remember:

http://ningpan.net/Publications/101-150/129.pdf

http://etd.gatech.edu/theses/available/etd-11202004-003552/unrestricted/wilde_timothy_p_200412_mast.pdf

The one thing to consider is that you can always open the bag up and add/replace the down as needed (or have a professional do it). I just gifted my son with a TNF bag that I got in the mid 80's. The reason why it is still in great condition is because I sent the bag back to them TWICE to have it cleaned and re-lofted to it's original specs.

hope this helps,

Matt

I have no idea exactly how much warmth you will lose each time you compress your bag.

My solution is to simply compress my bag as little as possible for a given situation. You're going to have to compress your bag to use it backpacking, so I can't really see any way around just making peace with the fact that you are slowly killing your bag's loft with each use and that's just the way of things.

With that said, my experience with down vs. synthetic fill is that down loses loft to a much smaller degree than synthetic fills. I have a 10 year old down bag that I still use regularly (and the loft is probably still 90% of what it was when new), but I've never had a synthetic bag last for much more than a couple seasons of extensive use.

I have no experience with the newest versions of Primaloft or Climashield though, so maybe they are better? I sort of gave up on synthetic insulation for sleeping bags a few years back.

What Ive always understood is that by the time you compress a synthetic bag 50 times, it has permanently lost "quite a bit " of loft.

I have a MH ultralamina that probably has 20 nights on it by my son in scouts. It is nowhere near as lofty as one hanging in the store, not even close. Cant say I ever remember it being though. Washing it might help, havent yet.

I dont recall the exact EN rating of mine, but I think it was around 25F. Mine weighs 2 lb 8oz. Less than the advertised 2 lb 15oz. Even with stuffsak its not 2lbs 15 oz. I do know he was never cold in it (in a tent), and was usually HOT taking his upper body out of bag some. Coldest night was downn to 22, but in a tent with another, so inside of tent probably didnt get less than 30.

I remember he said his tent partner was freezing in a cheap 40f synthetic bag, and asked him thru chattering teeth if he was cold. He said "No, actually Im kind of hot"

Washing it definitely helps. More so with down (which others have noted is definitely more resiliant), but it helps with synthetic too. Oils, dirts, etc. can really affect loft. I wash my bag about every 20 nights in it, unless it gets extra dirty for one reason or another.

I had a mountain hardware lamina 35. It was a nice bag when I first got it, kept me warm through the winter. Then after the winter I used it extensively all spring, summer, and early fall. There was a big gap between early fall and winter break when I finally got out again for a week long winter trip.
Throughout that year the loft had become incredibly damaged but I didn't notice because it was warm out. On the winter trip I had serious problems. I figured it would be mid thirties, but it was more like mid to low 20's. I was forced to sleep by a campfire every single night just to get some sleep. I spent one borderline hypothermic night up a ridge.
The day I got back I returned it to rei and said good riddance to synthetic fill.
Synthetic bags are good for someone just getting into backpacking and who can't afford a quality down bag, but they should be replaced with a good down bag once it wears out. Synthetic fill is cheap but not cost effective at all in the long run. Over time synthetic fill is very expensive compared to down.

Huh. That doesn't fill me with confidence…

1. What is the warranty from MH on your bag? If they are putting out a product with certain claims about it, then they should back up that product.

2. I know you're trying to get established in the writing business, so if you want an older MH down bag that's been sitting in an attic for 9 years (just "found" all this stuff that we stored) — PM me. It weighs 3.5 lbs, but if you only use it for bike touring, you could save your synthetic bag (uncompressed) for backpacking only.

I bought the bag from L.L. Bean. I had a great big useless gift card and nothing to spend it on; the MH bag was the closest thing to ultralight. Even if MH doesn't cover it in case of premature failure, L.L. Bean will (although I'll be stuck with $300 in a gift card and be back to Square 1!).

Assuming it doesn't fail, it's the nicest synthetic bag I've ever seen or owned or slept in. I would say I'm enormously happy with it. But, you know, time will tell.

Thanks Valerie, but I actually have an old 3.2lb synthetic EMS bag I can use as a beater. That's kind of you, though.

Luckily, and against all stereotypes and odds, my "getting established" period in writing comes with pay so I'm not suffering too badly yet ;D haha.

youll lose about 5 deg in the first or two year of NORMAL usage and another 5 deg or so after that IME for climashield

by normal i mean using it about 30-60 days a year outside stuffed loosely in your pack … this is what "normal" people do who cant climb/hike everyday …

i use my cats meow everyday indoors and out … we have no heating indoors so i sleep in it every day … however i dont compress it unless i need to and never in a stuff sack, just at the bottom at the bag

note that even the best down bags will suffer loft loss if used daily for years …. i use my EB down vest daily for years and its starting to suffer …

from a BPL member who basically spends hundreds of days outside a year …

Sleeping bag: I have been using Western Mountaineering sleeping bags most of the time and depending on the climate I am alternating between the Summerlite, the Ultralite, the Versalite and the Puma. Generally speaking the bags are high quality and very durable. After about one year of constant use the slider of the zipper can wear out. As all WM bags have two sliders and usually only the top one that is most used wears out this is not a life-threatening problem. The slider can be replaced very easily if you have the appropriate spare. After about half a year of constant use the down in the bag will start clumping and thus reduce the warming capacity of the bag. Washing will restore the loft, but still it is my experience that no matter how and how often you wash the bags, after one year of constant use they will have reduced loft and after 2 years of constant use the down has so much deteriorated that I am now thinking of replacing it after about 700 nights in it. I am now using a BPL 240 synthetic quilt.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=59312

;)

That thread was awesome, and surprisingly relevant to me as I've been living in a tent 95% of the time since August.

Maybe four years from now I'll end up making my own "constant use" thread…

I think a lot of synthetic bags get over compressed as they larger to pack. Just because a compression sack will approach black hole event horizon levels doesn't mean you should crank it down that tight. I store mine loose and don't try to go medieval on it.

The trick is to realistically size your pack for what you carry. Gaze with green eyed envy the photos of people hiking with tiny packs full of down: you ain't going there with a 20f synthetic bag.

The only reason to use a synthetic bag is wet weather (and I'm there). I'm talking about days of dampness and drizzle and living at the dew point, not just an occasional thunder shower.

just to add here is her actual site … as you can see she gets out ALOT for months at at time… more than most here

http://www.christine-on-big-trip.blogspot.ca/p/what-breaks-when-and-why.html

she has since added these thoughts on her sleep system …

After a lot of problems with clumping down due to extended use and/or humid conditions I have now changed to synthetic quilts. I am using a BPL 240 quilt for 3 seasons and a Enlightened Prodigy 20 for colder temperatures. The BPL quilt has about 300 nights and the Enlightened Prodigy about 120 nights of use without any significant deterioration of loft or any other substantial defects.

also some might find this interesting …

Clothes: Here is some good news: Clothes like T-shirts, fleece pullovers, trekking shirts and pants have a surprisingly long life expectancy. No matter whether you buy cheap no name/generic stuff or expensive brands outdoor clothes survive up to a year and more before they start falling apart. It does not pay off to invest a lot of money into brand stuff. Pants have a shorter life expectancy and survive only about 6 – 9 months before the zippers start wearing out or the fabric starts ripping. But if you have chosen a light colored (T-)shirt you will encounter a cosmetic problem first. After a couple of months of wear the shoulder straps of your backpack will start rubbing off onto your shirt discoloring it. No washing machine will be able to remove those discolorings and the shirt will always look dirty. Either chose a dark color or live with the discoloring.

Insulation jacket: I have used a Montbell Thermawrap jacket for 4 years and it still has gotten some life in it. To my big surprise the zipper has not worn out yet and the synthetic insulation is still decent, though degraded by several washes and hundreds of times being compressed into the little storage bag. I will definitely buy it again.

;)

Uh oh. Just when I thought I had wrestled an understanding out of this thread, Eric teams up with a super-hiker to set me back to square 1…

For the record, if my synthetic bag loses 10-15% warmth in the first two months and then stays like that for hundreds of nights, that's awesome by me. I don't know if this is the case, though. I do think that the quality in MH's Ultralamina bags is probably on-par with the synthetic quilts she's using, since it's been so good to me.

Christine is definitely the real deal, but her experience does not match most people's. For example, I've got a Feathered Friend's down bag I've used for 3 thru-hikes, and a Marmot down bag I've used for two more, and if they've lost any loft at all I haven't noticed it. I usually wash my bag about once every four months of use.

I've had some expensive synthetic bags, all of which have lost more and more loft as time goes by.

Yup, synthetics are better when wet. I choose to keep my down bag dry and have a lighter, more compressible, longer lasting sleeping bag.

I store my sleeping bags hanging up or in a huge storage bag that barely compresses them.

No to discount Justin Baker's story, but I think BPL'ers are definitely subject to prejudice based on emotion rather than data from time to time. A single trip with a loftless synthetic bag is not an indication that all down bags are better, or all synthetic bags are worse.

I am certain Justin's bag lost loft and that this made him cold. I am not certain all synthetic bags are a hypothermia risk compared to down because of loss of loft. I don't want to condemn every manufactured synthetic without reason.

I think Christine's account should be an indication that looking deeper into the life of synthetic is worth it.

I've sent an email to MH to this effect; I'll let you know what they say (however anecdotal that turns out to be).

BPL definitely has a "group think" mentality at times …

not to say that synth doesnt degrade faster, or that down can last longer … generally thats true

but one needs to be wary of many "accepted truths" on BPL

i remember years ago having to argue that fleece works just fine in certain conditions … and that synth has its uses, even pointing out previous articles from mr. jordan using synth on BPL didnt convince many people at all

in fact it probably wasnt till mr skurka's "stupid light" article where he wished he had a fleece, that fleece and synth once again became more "accepted" for certain conditions on BPL

like all intraweb forums, on BPL we all like to think were always right and my way is the only way

myself included

;)