Underquilt stored in the pack... OK, or No?

**hutzelbein** · 10-30-2016, 12:42

Originally Posted by Carrico

the conflicting information that bothers me is, are the fibers damage from the actual compression or being stored compress for long periods of time?

I would assume both. Overcompressing down or synthetic would surely damage fibers. And most materials loose form when kept under tension for a long time. I think down is a bit more resistant to this than the current synthetics, though.

Nonetheless, I would not compress my down gear for long times if not absolutely necessary. Get a big bag and simply store the quilts next to your pack. It only takes 5 more minutes to stuff the quilts into the backpack.

**bamudd** · 10-30-2016, 14:33

Originally Posted by W8lkinUSA

I would probably relate it to a spring. The more frequently (and intense) a spring is compressed (think car suspension system), the sooner the spring will lose its strength.

I wonder this as well. For example, it doesn't matter if you store your magazines loaded because it's not the compression that damages the springs, it's the cycling.

I don't know about insulation.

**Carbon** · 10-30-2016, 15:28

The down loses its loft just like the spring can lose its original unsprung length.

**W8lkinUSA** · 11-01-2016, 14:43

Originally Posted by bamudd

I wonder this as well. For example, it doesn't matter if you store your magazines loaded because it's not the compression that damages the springs, it's the cycling.

I don't know about insulation.

I'd imagine new magazines provided a greater spring force, then older springs. How are your fully loaded magazines a decade or two later?

As a newbie, my car's clutch system was highly affected when I stepped on the clutch at red lights; I wait in neutral gear nowadays.

**Caminante** · 11-01-2016, 15:44

My solution for your scenario would be to get a $1 laundry bag from the dollar store and keep it in that in the van, then put the quilt in your pack if you get a window of opportunity.

If just compressing a down bag/jacket/etc. damaged it, they'd be pretty useless since you couldn't ever pack them. Speaking from a purely empirical standpoint, and making no legal claims, I've owned a number of down items and can't say that I've ever seen one "give up the ghost" with the exception of an old army bag that was surely decades old. I've even "lost" a down sleeping bag in the attic, in its stuff sack, for almost a year and it still lofts fine. However, I do not in any way recommend trying that.

I keep my down quilts in the $1 laundry bags I mentioned at home in the closet, pack them when I need to, use them when I get to, and I'll replace them as I have to (I doubt that is anytime soon).

**Carbon** · 11-01-2016, 15:55

Even my Big Agnes sleeping bag, in addition to the compression sack, also came with a large mesh storage sack.

**gfortune** · 11-01-2016, 16:05

Originally Posted by cmseeley

Thanks for the tips all. It did come with a storage bag. I was just curious if there was any kind of suggested maximum time frame that it is ok to leave it in the stuff sack.

I got an HG 20 Incubator last year and it came with a small nylon bag. Definitely not the sort of bag I would store it in long term if I could help it. It's more stuff sack than storage bag. My down is currently in a couple big plastic tubs so it's not compressed at all.

When I'm getting ready for a trip, the plastic tubs travel with me and I stuff and load at the trailhead or the morning we leave for the trailhead. Might be extreme, but I'm trying to baby this gear as much as possible. I'd like the initial purchase price to last as long as humanly possible

**kitsapcowboy** · 11-01-2016, 17:28

It is worth mentioning in this thread, regardless of how durable any insulation product happens to be in the face of either extended compression or compression cycles, that not all "stuff sacks" are created equal. Any storage bag has a volume that can be expressed as a function of the total volume of the quilt it contains at maximum loft, i.e., 0% compression. That means a loose storage bag might compress a quilt only slightly, say down to 95% of its maximum volume, or 5% compression, while a moderate stuff sack might compress its quilt at 50% and a compression sack cinched down very tightly might compress its quilt at 80% or more. Thus, the mechanical effect of the sack on the insulation in the quilt and its potential for damage when stored long-term may vary greatly.

The approximate maximum loft volume of a down quilt in would be its length x width x average baffle height. Therefore, an 80" x50" down quilt with 2.5" baffles (average height) has a maximum loft volume of 10,000 cubic inches, or 163.9 liters; if you store it in a square-bottom stuff sack that packs out to 13.5" in diameter by 18" tall (40.6 liters), you'll compress it to 26% of its maximum volume, or at 74% compression.

The maximum loft volume of a Climashield synthetic quilt can be approximated given a rough average loft of 1/4" per ounce of insulation. Thus, a CS 6.0 quilt has approximately 1.5" of loft, and an 80" x 50" quilt of that thickness would have a maximum loft volume of 6,000 cubic inches (98.3 liters), so packing it into the example (40.6-liter) stuff sack above would only compress it to the 57% level.

Obviously, the mechanical effect of compression on insulation is not a linear one, but rather exponential in nature. Compressing identical quilts long-term at 90% and 80% of max volume respectively (a 10% difference in compression and an 11% difference in occupied volume) probably has negligible effects, but compressing the same two quilts for an extended period at 20% and 10% of max volume respectively (the same 10% difference in compression but now a 50% difference in occupied volume) could produce significant differences in effect on the insulation, not to mention meaningful damage to the quilts over time.