Down Sleeping Bag Question

Compression sack: No. Lots of anecdotal evidence claiming tight compression damages the plumes over time. I let my down just fluff up and fill all the nooks and crannies in my pack liner to minimize compression. You're not supposed to store it in stuff sack long term so why do it short term if you don't have to?

If you don't compress it, you can pack it the day before imo.

I don't drape mine over my backpack, ever. Then again I live in a place with minimal humidity where our trails are surrounded by spines and thorns and well maintained looks like bushwhacking in many other places (and our sun bleaches fabric after just a few days). Draping a sleeping bag sounds like the best way to literally rip it to shreds out here. So I'm probably not the best source of advice on that question.

I use a CCF pad unrolled inside my pack for structure, then a pack liner goes inside the pad, then the sleeping quilt gets stuffed into that. If things are dry, I'll put clothing, especially any insulation layer inside too. Then I roll or twist up the top of the pack liner and pack remaining items on top.

There is some "light" compression as things get placed into the pack but nothing like a compression stuff sack.

I will usually leave my sleeping quilt in the cotton stuff sack in the car if I am driving a while to a trailhead. However, I putter at the TH, and I usually wish I would get completely packed at home, where I can just pull up to the TH and put the pack on. I don't think you'll do any longterm damage with packing the day or night before.

+1 on the cloud packing suggestion. For no other reason than otherwise you are packing a huge solid brick in the bottom of your pack and are wasting valuable space in the bottom. Let the fluffiness of the down fill all those nooks and crannies that will otherwise go unused.

Generally, anything up to about 10:1 compression will likely not harm down in a sleeping bag.
Link to: http://ningpan.net/Publications/151-200/176.pdf
"Compression behavior evaluation of single down fiber and down fiber
assemblies", Jing Gao ab; Ning Pan c;Weidong Yu a a College of Textiles, Donghua University, Shanghai, People's Republic of China b Key Laboratory of
Textile Science & Technology, Ministry of Education, People's Republic of China c Biological and
Agricultural Engineering Department, University of California at Davis, California, USA
First published on: 08 January 2010"
(As copied from the PDF file I was looking at…)

This is one of few that actully study down compressibilty and recovery.
This is the conclusion at the end of the paper:
"Conclusions
Physicomechanics of fiber itself influenced assembly compression
and recovery, so the bending properties of single
down branch were quantitatively analyzed at first in this
paper. The data show that the equivalent bending modulus
of down fiber is much lower than wool, and the rigidity is
1/10th as low as that of wool. There is a hysteresis loop
during bending and recovery courses of single fiber, the
possible explanation for which is the internal friction and
slippage between the fibrils and themolecular chains.Down
has less hysteresis loss thanwool, because ofwhich it is considered
that down has better bending-recovery ability than
wool. We think that it might be owed to the more compact
crystal structure of down.
Down fiber assembly has the better compressibility than
wool. The morphological structure and physical properties
of single down fiber are considered to greatly contribute to
that. The large numbers of bifurcate structures on both the
down branch and down fibrils could occupy abundant space
and make down fiber assembly greatly bulky. That provides
enough porousness for assembly deformation. In addition,
the lower bending rigidity of single down fiber is the other
factor to make assembly compress easily. When the pressure
on assembly is slight, the plentiful fibrils on down branches
and the triangle nodes and crotches on down fibrils extend
provisional support function to the down branches. So the
Vf of the assembly has a slow change phase at the primal
pressure of 0–70 gf. Contrarily, when the pressure vanishes,
the bifurcate structures prevent assembly recovery again.
So the down fiber assembly exhibits poor compressionrecovery
ability. The appropriate agitation is an effective
approach to unlock the intercrossing among the fibrils or
the nodes or the crotches and make the contacts among
fibers separate on the instant.
In addition, the lower bending rigidity of single down
fiber and the better compressibility of down fiber assembly
mainly contribute to the soft handle of down and down
assembly."

Basically this says once compressed, say by a factor of twenty or so, it tends to stay that way because the fibers interlock. Shaking the down out will loosen the interlocked fibers again, allowing the bag to loft fully again. It takes really extreme pressures to do permanent damage to down plumes, in agregate. Note that dirt, moisture, the presence of any oils, etc. is NOT considered. Nor do they mention static repulsion which can be considered a minor loft aid in seperating fibrils connected on a single somewhat dryer plume, as is normally used. Anyway, enough of the scientific type gibberish.

Soo, back to your questions after the explanation.
"Compression Sack? yes or no" Yes.
It actually depends… Give your bag a good shaking out, if you use a compression sack. Compression/dry bags have weight which can be avoided by not using them. For those that consider the reduction in volume worth it, just remember to shake them out before sleeping. Personally, I use them. Using compression sacks, I get my base pack weight down to reasonable for most outings and volume down to very small. Example: 17# for a week long (6 nights, 7 days) using a Murmur. I was accused of carrying a "glorified purse" in the past. Small volumes let me save about as much weight (by letting me use a smaller, lighter pack) as not using a compression bag would require. Works for me. The sack *just* fits into the bottom of the Murmur.

"Packing the day before? yes or no" Yes.
As above, it doesn't really hurt dry down to be compressed for a couple days. It will shake out, though it does take a bit longer, maybe a minute rather than 30 seconds…for example. Down will take a "set." Leaving it compressed for three or four days is not something I would do or recommend. Even a 2×4 can be warped with pressure on it for long periods of time. Down is much more delicate. But, occasional compression for a couple days won't do permanent damage.

"On average how long should it be draped on backpack the next day?"
That one is tricky. Depends on the climate…Generally, I leave mine out while I make coffee, packing into the sack just before loading the pack. Once ever few years, it gets a bit of moisture, or spray. I generally stop early and hang it out on a few trees and shake it out every 5-10 minutes or so to dry, if possible, when this happens. Otherwise, I know that my body heat will dry it over the course of a night, pretty much. Though, I have been known to wake up cold, climb out and shake it out good and climb in, again. Sort-of like exercising to warm you up at night. But, this happens rarely.

by the guy that answered the phone a western mountaineering. first he pointed out how their bags are stored and shipped which is compressed. he then went on to explained that using a compression sack is not so much (unless you super compress the bag) a damage issue as it is attaining full loft when it's time to use the sleeping bag. if the bag is heavily compressed it could take a couple of days to regain full loft. not something you want to happen. he said the stuff sacks that come with the bag are the best balance between compressibility and regaining full loft in a reasonable period of time. he also didn't see much of an issue going without the stuff sack (which i do) and just putting the sleeping bag into the bottom of your pack.

Exactly. People that work with down, and have to maintain guarantees, know that compreesing down is not a real issue. Hmmm, as I remember the military supplies artic survival kits (or used to) on planes that include down coverings. These are vacume sealed in small packets typically at very high compression ratios for long periods of time. Some damage is done, but space is more valuable. Going without a compression bag is never an issue, of course.

The resiliancy of down means that it will start resisting pressure long before the down is damaged. It is doubtfull that damaging force, except locally, could be applied by hand using a compression bag. Every fiber will resist you, giving a LOT of resistance, in total, even if the individaul resistance is slight.

I will note that WM does not mention shaking/agitating down from what was said. As mentioned in the paper, there are nodes within down that can "catch" on other fibers. Shaking down is an easy way to restore loft(again, referencing the above paper.) Note that the wording is odd because of the translater used.

Some of the lighter bags/quilts are intentionally under filled. Used in conjuction with continuous baffles, this also allows you to shake down around a bag for maximum effect. Shaking it towards the bottom usually means a cooler bag. Shaking to the top means a warmer bag. And, of course, you carry a lighter weight.

Since as much or more heat loss can be through conduction with good down bags, rather than through air loss or convection within them, there has been a LOT of interest in sleeping pads the last 10-20 years. Using a good pad, many claim cold weather sleeping under a quilt is comfortable. Using a NightLite (Mt. Washington or Nunatak Luna) with a bag, I find them to be warmer than the R2.5 would suggest, warmer than a 1/2" pad of about the same weight by considerably, though the thinest portions are only about 1/4". I would suggest that the bumps supply loft pockets allowing the down of a bag to loft more than a flat pad. NeoAir's also supply a similar effect, though not as pronounced, since they are simply designed to hold shape, but allow lower pressures to be exerted against some areas of your body. The Klymit Inertia takes this effect to a bit of an extreme with Loft Pockets, a happy coincidence with body mapping.

Compression Sack? – It is optional. My 3 season bag packs so small (6×10" in the original stuff sack it came with) that there is no reason to bother. Depending on the trip and what I am carrying I might stuff it in the original stuff sack or I might pack it loose in the pack. If using a bigger bag or if space were more critical, I'd use a compression sack.

Packing the day before? – Yes

On average how long should it be draped on backpack the next day? – No need to IMO, unless it needs to dry or air out and you will be making camp late that there is no sun left and/or you are going right to bed. I have never hung my bag on my pack, ever.

I'm with most of the others and just stuff it loose in the bottom of the pack.

I usually pack everything a day or two before a trip, I don't have any problem leaving it compressed for a few days. It spends nearly all of its time fully lofted in storage, I'm not worried about the effects of an extra day being stuffed.

I've never draped my quilt over my backpack. Do you mean stopping sometime in the middle of the day and letting the bag dry out? I've never done that. I usually wait to pack up until I'm done with breakfast then as soon as I get to camp I set up my shelter and pull my quilt out to begin lofting again. The only time I'd consider pulling it out during the day is if it somehow got wet but its a down bag so I avoid that at all costs!

Adam

Compression sack sounds risky, but stuff sack is fine— as pointed out above. There are several styles to packing, so another +1 on this method:
Use a stuff sack. It frees up a LOT of volume in your pack for other stuff. That’s a big help if you carry a small pack. The extra clothes (like socks and long johns) help fill the nooks and crannies.

+1 on packing a day before.

-Barry
-The mountains were made for Tevas