FYI re: Rayway quilt insulation

[Jeffrey Wong]

<p style=”text-align: left;”>The saying goes:  Funny thing happened on the way to the forum. ..</p>
In 2014 I made a Rayway quilt, alpine weight. Loft 1.8″. Good to 30 degF. I used it for 25 nights on the PCT in 2015, using a large stuff sack for minimal compression , then sent it home in favor of a Zpacks down quilt. It came out of the stuff sack a month after I shipped it. Aside from that trip, I’ve had it in the stuff sack maybe 30-50 times.

It has always been really hot until the last week when it suddenly seemed cold. I inspected it: the loft had dropped to about 1.125″ or less. Strange that it should change  so suddenly. Looks like I have a little Climashield project ahead of me,  if I don’t give it away. I hope this doesn’t happen with Climashield! (Does it?)

[Anonymous]

All synthetic insulation so far, has loft that degrades much more quickly than decent and high quality down. The continuous fiber batting like Climashield is the most durable of the synthetics. Also generally speaking, the finer the fibers become (for synthetics), the better they still air, but the less durable they become. This is why many synthetic insulations use a combo of thicker fibers with thinner fibers. The thicker fibers are for the structure/durability and the finer fibers are for greater insulation at lower weight.

If Dyneema or Spectra type fibers can start to be produced smaller than 50D and closer to microfiber size–they might give down a bit more close competition as to weight and durability since this material is about 30% less dense than polyester (most common material used for synthetic insulation) while being more durable.

[James Marco]

Jeffrey, yes, that happens. Once it reaches about 1/4 to 1/3 of it’s initial thickness it slows down a lot. But any loft is mostly gone and with it the warmth.

Synthetics are about equivalent to cheap down when new. 550-600fp or even 650-750fp for some of the newer stuff. But, given the rigors of backpacking, it quickly degrades. You might not notice it on a day to day basis. But, I don’t think a 20F synthetic will last a thru hike of the PCT without help, say 100-150 nights. Generally down will last a LOT longer and compresses tighter/smaller the whole time. Volume can also save weight.

Actually, Dyneema and Spectra are Ultra-high-molecular-weight polyethylene. As such, they are made up of long straight chains. This is NOT ideal for thermal insulation. Mixing this with other forms of plastics does not produce a twisted fiber which would be more ideal for insulation. It only produces a regular gridded molecule. (A helix twist allows a thread to take up maximum space between threads, thus giving more air pockets (think loft) to a thermal insulation.) Spectra/Dyneema just lay flat allowing minimum space between threads. This results in a relatively poor and heavy insulation since none of it’s mechanical strengths are used.

Mechanical production of a down substitute does occur. But, random sized down plumes, random down fiber thickness, random branching to barbules, etc all conspire to keep down on top. Machines are great at producing the same thing over and over. It is currently not possible to reproduce artificial down clusters with the same properties. Indeed, even the strength of most materials fail compared with natural sources, example spider silk compares with current benchmarks for aramids but is lighter. Rayon, nylon, etc are all attempts to reproduce silk. Complex structures are still beyond us.

Indeed, the older Holofill was polyester, also. Again, it suffered from longer straight chains of molecules. They tried to fix this by making micro-tubes (hence the name holofill -“hollow fill”) and mechanically interlocking fibers. Yup, this helped. They all suffered greatly from compression (think kinking of the tubes.)

While they do have a higher resistance to water, it has been my experience that sleeping in water is always a cold night. Doesn’t mater what type of insulation you use. You have to avoid sleeping in puddles.

[Jeffrey Wong]

Thanks.  I did once sleep in the zpacks quilt surrounded by an inch of water when snow melt from a May storm gathered and flowed over my ground sheet.  Happily, I was on a 2.5″ Neoair, which kept me high & dry.  Location, location, location!  :)

Well, I’m encouraged that Enlightened Equipment, which most people regard highly, uses Climashield on some of its quilts.

Cheers!

Jeff

[Anonymous]

James speaking of synthetic insulation: “But any loft is mostly gone and with it the warmth.”

I’ve seen a few posts here (including at least one by Richard N.) talking about how synthetic’s loft loss does not lead to a corresponding, 1 to 1 ratio loss of it’s Clo value. I think the theory is that the original loft has a bit too much open space to begin with that allows a certain amount of convective heat loss, and as it compresses the fibers get closer to each other becoming a bit more efficient in that.  Yes, course it does lose some Clo value, but not as high as one might initially think when thinking solely in terms of loft=insulation.  I don’t remember the exact ratios, but it’s something like, some synthetic insulation’s can loose up to 40 to 50% total loft (and fairly quickly), but lose around 10 to 20% of their Clo value in connection.

“Actually, Dyneema and Spectra are Ultra-high-molecular-weight polyethylene. As such, they are made up of long straight chains. This is NOT ideal for thermal insulation. Mixing this with other forms of plastics does not produce a twisted fiber which would be more ideal for insulation.”

Yes, these forms of PE (and all forms of PE really) are pretty conductive, but that doesn’t matter much in lofted materials where a lot of air is being stilled.

Fiber shape can have some effect on insulation efficiency, but it’s minimal compared to the thickness/fineness factor–particularly in relation to continuous fiber batts like Climashield.  You would NOT want to use Dyneema/Spectra as loose fill–totally agree on that, but as a thin strand, continuous fiber batt, it would be ok and it’s durability (not so much it’s mechanical strength) and lower density would come in handy then.

I’ve haven’t looked at Climashield Apex fibers under a microscope yet, but I suspect there is nothing special about the polyester filament/fiber strands they are using as to shape and the like. They are coated in silicone I believe to help with moisture resistance. They are probably your typical, round extruded fibers.

Anyways, it’s kind of a pointless discussion since apparently manufacturers cannot make highly oriented UHMWPE fibers smaller/lighter than 50D currently (which is way too large/thick for insulation purposes).

Also speaking hypothetically, but somewhat less than the base premise, is that one could plasma treat the surface of the Dyneema/Spectra/UHMWPE fibers (once small/thin–smile) and then bond a stiffer, shaped, and/or less thermally conductive material to them and thus also potentially use it also as loose fill.

None of this will matter too much once advancements are made (and they are being made currently) in flexible, durable polymer aerogels. These have the capacity to eventually rival and maybe even surpass high quality Goose down as to Clo per weight values, though probably not in compressibility.

[James Marco]

Justin, Yeah, I agree. Loft does not equate directly to warmth or insulating value. Even down does not loose its warmth when damp and starts compressing. It only looses some of it. But, that is pretty much the same for any fibrous matrix including down. Soo, even though it is incorrect, I sort’a ignored it. Down has to be pretty wet to actually collapse. So do synthetics. But, synthetics have more stiffness in the fibers holding an airspace better when wet. Still, I would much rather stay dry.

I should have written “much of its warmth” and not had everyone inferring that an inflatable blanket would be as warm as one stuffed with insulation.

Yup, aerogels promise to change the way we do things, maybe we will see some sub 4oz, 20F quilts that will last as well as down in the future.

[Elliott Wolin]

Try washing it.

I had an old synthetic vest I made, maybe Polarguard, that looked like it’s days were over.  But after washing it lofted up to almost new.  I used mild soap, gentle cycle in washer (I don’t do down in the washer, only by hand in a tub), then tumble dry with some tennis balls.

[Joe S]

I read on here somewhere that synthetic insulation decreased in warmth 10 degrees in the first year and then 3 degrees every year after that.  I do not know how true this is, or what degree sleeping bag or quilt it was based off of since it would be different for a 0 degree bag and a 50 degree bag.  Of course usage, storage, and washing it would all effect the reduction of warmth, but I do not know what the implied usage was in that original guide line along with what type of insulation it was.  But whatever the real numbers are, the warmth definitely plateaus after a while.

[Jeffrey Wong]

These posts are so informative.  Thanks, all!

Justin, I used that Rayway quilt on the PCT for 2 1/2 weeks down to temperatures I estimate at 45-50 degrees.  Now, it can’t keep me warm at 65 deg in my house, though part of that might be that my cold tolerance has suffered from having lost 2 more pounds than what I gained after finishing the 2015 hiking season.  Aerogels sound intriguing–how does one follow that progress?  I haven’t seen any of the same stuff you’ve been reading.

James, yes, I would have been miserable for many nights after the synthetic honeymoon.  I was just lucky that my fellow hikers clued me into just how massive my Rayway was (in both weight and stuffed volume), that I called zPacks while at Ziggy and the Bear’s at the I-10 and took delivery at Big Bear.

Elliott, thanks I may try washing it.  If it revives, I’ll never stuff it again.  If it doesn’t, I hope the comfort rating levels out as Joe remarked and it’ll be a 65 degree quilt.

Happy trails, all!

[Anonymous]

Hi Jeffrey, the latest development in aerogels that I know of are the polymer aerogels and more specifically the kind that use Kapton/polyimide. These are stronger, more durable, and much more flexible than other forms of aerogels, while still being fairly low density and highly insulating.

I had contacted a company that sells thin sheets of this type of material, but while they initially responded back, I never heard back as regards specific pricing.

One thing I am fairly certain of, is that this material will at least be really good for sleep pads in combo with some air or a little foam for comfort (you could have a honeycomb foam grid backed with thin sheets of the aerogel for example).

But when it comes to sleeping bags and quilts (large volume and need for high compressibility), I think Goose and Eider downs will continue to remain the best all around for awhile.

[Author]

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