Synthetic degradation question

We discussed this ad nauseam last week, so I'll summarize what I can:

Yes, it has lost loft. How much depends more on use and storage than time.

The shell material and insulation itself has likely not suffered at all from time if it was stored uncompressed in a dry, dark space. It takes a lot longer for UV damage to break down a shell than 10 years.

If the bag was used a lot, especially under compression or for repeated nights, it has likely lost somewhere up to 20% of it's loft. Extensive use could lead to more loss in insulative properties.

If you wash it with Nikwax Down Wash or similar, you'll restore some loft. Put it in the dryer on low or no heat for a long time with a few tennis balls (but wash the tennis balls, or the bag will smell like chemicals).

The best answer is to test it and see where you're comfortable to. Depending on the manufacturer, you may be able to get it restored or replaced.

As a general rule, all synthetic sleeping bags get compacted over time, typically faster than down insulation will. If you store it compacted, this speeds up even more. So, if you know how much loft was in your bag when you brought it home from the store, and then if you measure the loft now, you will see how much compaction effect there is.

If you take your sleeping bag out and shake it, then twist it 90 degrees and shake it again, and then repeat that, you will get just about as much loft out of it that you can.

–B.G.–

Thanks Max. Could you point me to the thread where it was discussed. I searched the forums, but I am not terribly skilled at using the BPL search function. Thanks!

(Found it. Not really about how to tell/measure degradation but still relevant to my situation. Thanks.)

Thanks Bob.

I don't know what the original loft was (it is a TNF snowshoe) but I will definitely try the twisting.

It has also never been washed, so I may give that a try. In recent years it has been stored uncompressed, but I honestly do not remember how it was stored for the first few years of its life. Given that I was still a noob, I suspect I mistreated it in its early years.

Christopher, there are a couple of issues here.

Synthetic insulation degrades with use. I've yet to see any good quantification of how much and under what circumstances. I wouldn't expect a stored bag to loose anything. Polarguard Delta is probably a bit better in this regard than Primaloft, due to differences in construction. I do not think washing it will do much good unless the bag is really filthy.

There's also the question of how accurate that 0F rating was to begin with.

The only thing to do is test it out. Sounds like a backyard campout is in order.

To give you a data point, almost four years ago I built a synthetic quilt of Polarguard Delta and Climashield. For me, it was a 20-25F bag when new. It's probably been used somewhere around 300 nights since then. Now I'd estimate the warmth has dropped to 35-40F. Not bad in my book.

Thanks David. I live in downtown Philadelphia, so no backyard. My neighbors would likely call the cops if I set up camp on the sidewalk.

I'll have to plan an actual field test with a "B" plan … unless BestBuy or the Apple store is releasing something new in the next week where everyone is camped out.

del

I've had good luck with synthetic bags and clothing being washed and dried to restore some lost loft – I think the dryer does most of the good, BUT you have to be very careful about temperature. A hot dryer will trash the bag, and some laundromat dryers are too hot even at their lowest setting.

Thanks Rick and Paul!

I intend to wash the bag and see what happens. I'll be careful.

Rick, I know the Polarguard Delta was supposed to be 2.45clo/inch loft when new. My bag presently is between 3.5 and 4 inches double sided loft. Unfortunately I have not yet figured out how to interpret this data! LOL.

del

I would suggest hand washing or using a front loader at a laundromat. Anything else will likely tear the bag up too much…if it even needs a wash.

Like some other posters, I would say it was probably a 10-15F bag at first and depending on how much use it's seen it could be degraded to 20-25F range. If you and your insulating clothes to it, you should survive most winter conditions but may be cold all night =/

Awwww man.

Here I thought I had a mildly degraded zero degree bag in my closet. 35 degrees would be worse than my summer down quilt!

I guess it's better to know now than freeze later … although freezing may be my only choice. At least it will be a conscious decision.

I would not assume that its a 35F bag from loft measurement alone

You have to test it out in the field to really find out

Measuring the loft of synthetics and deriving insulative values may not be correct

A case in point the new PL synergy that patagucci promotes on their DAS has 80% of the clo of PL1 … Yet its "loftier" (thicker) …

The othet question to ask is whether yr old bag rating was exagerated even when new … Not uncommon with old bags

Read this to userstand thermal ratings

http://www.mammut.ch/images/Mammut_Sleep_well_pt1_E.pdf

Ill post up some 90s us army research that shows the problems with trying to figure out "wamth" from loft in synthetics when not on an iphone

;)

Inches of loft is not an accurate way to measure warmth; not in down, and absolutely not in synthetic fills.

Can I take that original 2.45 clo/inch for Polarguard Delta and have it mean anything at this point, or are those numbers only relevant when new?

If u do the math and assume a total clo of ~8-8.5

You can go here to richards graph and make a guess…

Of course other things such as fit or your body type may affect "warmth"

http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/9378/index.html

;)