Nov 13, 2009 at 6:48 am #1241652
Good morning, all!
I'm an experienced hiker/camper, but relatively new to lightweight camping, and I'm interested in making some of my own gear.
Recently, I bought a Hennessy Hammock, which I'd like to adapt a bit for cold weather. I know they sell a lot of "add ons" for cold weather camping, but this might be a good place for me to start my experimentation.
To start, I was looking for a thermally reflective but breathable layer. I found a fabric called "Insul-Bright" that is polyester (good wicking characteristics?) needle-punched through a mylar space-blanket.
Does anyone have any experience working with this material? I've emailed the manufacturer for specifications, but have received no reply.
Thanks in advance for any info! I think this will be a fun adventure!
TedinskiNov 13, 2009 at 8:03 am #1545017
The following are a couple of my lab photos showing the construction of the insulation. The first photo is at 10x and the second is at 60x.
The insulation, in combination with the appropriate undercover design, could achieve up to a ~R 7.6 value (2F LLimit or Comfort temp). In order to approach this R value you would need to suspend the Insul-Bright layer so that it is uniformly about 3/4" below the hammock bottom contour. The perimeter of the Insul-Bright would also have to be at this distance and sealed to the hammock bottom. The HH Under Cover, or equivalent product, would then need to be suspended, with the same gap structure, below the Insul-Bright.
If you plan on just using it like a CCF pad, you will be sadly disappointed in its performance. In that configuration it will provide less of a R Value than a 1/8” Thinlight.Nov 13, 2009 at 8:13 am #1545020
"…could achieve up to a ~R 7.6 value (2F LLimit or Comfort temp). In order to approach this R value you would need to suspend the Insul-Bright layer so that it is uniformly about 3/4" below the hammock bottom contour."
I recall from some of your garment discussions that 3/4" air gap contributes to the overall performance. But this is often difficult to achieve and maintain, and a greater gap leads to a fall in performance.
What would you estimate the R-value to be if the Insul-Bright were in "uncompressed, near contact" with the bottom of the hammcock?
Thanks.Nov 13, 2009 at 8:15 am #1545022
Unlike most, I DO work with this fabric on a daily basis. Is it what you need? Maybe, maybe not. You do need to protect it from hard abuse. It isn't that it is fragile but it will wear faster. As a tent liner on the floor it is good (a trick I have used to be warmer in winter….and it doesn't crinkle like mylar does.)
As for sewing it, the material sheds bad when cutting. DO vacuum up right after cutting and keep kids and animals away. It also frankly is a great duller of rotary blades.
For an American made fabric it shines many certain applications. Whether it works for you….I don't know.Nov 13, 2009 at 8:17 am #1545024
Don't email the company! Just pick up the phone and call their headquarters/offices in Lynwood, Washington and talk to a real live person.They *gasp* have real people that answer the phone ;-)Nov 13, 2009 at 8:42 am #1545032
First a caveat; the patent says, "The individual contributions of the separate insulative materials is not completely understood…"
In this configuration, Insul-Bright would provide about the same R Value as a 1/8" Thinlight. I don't have the time to get into the radiation computation details but, the degree to which the IR component of Insul-bright insulates is dependent on both the orientation and distance from the heat source.
Insul-Bright is primarily used for hot pads and cozies. In this environment it competes with CCF and Thinsulate. Thinsulate uses the same big polyester fibers that you can see in my Insul-Bright photos. They augment that with very fine and dense polypropylene fibers. These fine polypropylene fibers accomplish the same thing as the Mylar, when used in a close proximity application hot pads, cozies, and near contact under covers.
In summary, for close proximity applications like hot pads, cozies, and bottoms of hammocks, Insul-Bright is generally equivalent to CCF or Thinsulate alternatives of similar thickness.Nov 13, 2009 at 8:51 am #1545034
Thanks, one and all!!
Such quick responses are rare… fast responses that are USEFUL are even rar-er! :)
So, to get my 3/4" air space, could I use a 3/4" "batting" above the Insul-Bright? that way, I could use a snug-ish fit to the bottom of my hammock without trying to hang it with such precision.
My initial thought was to use the Insul-Bright as a top layer for a thin quilt/pad for use INSIDE the hammock (therefore the need for wicking & moisture transport, as it would be close to the body). You've already saved me a lot of experimentation!
Speaking of R-Values, if the 3/4" fill, plus the Insul-Brite, gives me a comfort rating of 2F, why would I need the other under-quilt at all? That's a better rating than most of the underquilts I've seen! I suppose this would be less compressible…
I'll have to call the company for the specs. Thanks for the heads-up on that.
Thanks again, everybody! More thoughts?Nov 13, 2009 at 12:10 pm #1545108
trying to wrap my head around this 3/4" gap…
Does it HAVE to be empty air? Could it be down? If it's OK to have some sort of fill, would that fill need to be IR transparent? Just trying to understand the issue.
Same sort of question regarding the "outside" of the Insul-Bright. I understand having some dead-air space is good for insulation value, but what is the mylar reflecting on this side?
The more I think about the issue, the less I understand it, and I work with heat (albeit in a vacuum) all the time.
T.Nov 13, 2009 at 12:24 pm #1545114
Sarah: I'm intrigued when you say you use this material every day!
how many things have you made from it, and how has it worked out? what's the BEST use for InsulBright, that you've found? How has it NOT worked out?
It just seems like such NEAT STUFF! I'm amazed I haven't seen a lot of threads regarding it, unless of course I'm missing something obvious, and it's been thrown to the side years and years ago. :D
T.Nov 13, 2009 at 5:48 pm #1545175
Thank you again for the reality of "use as designed or nothing much is gained" caveat.
Much as I dislike losing some magic material to radiation physics, I much pref that to wondering why my "super quilt" doesn't do the job.
I appreciate your thoroughness.Nov 13, 2009 at 6:14 pm #1545181
It is what we use in our FBC cozies that we produce ;-)
I have also used it in clothing, tent floor liners, etc. We buy it in the big commercial rolls at quite the discount so I never feel wasteful trying it out on new things. If I was paying (gasp!) $6 to 8 a yard I wouldn't be so willy-nilly to cut up new items ;-)
PS: It works well for a sewn pot cozy as well. Just do keep away from flame.
The coolest part is that the fabric is manufactured in a plant only a couple hours away. Not often does that happen these days!Nov 13, 2009 at 7:34 pm #1545185
I need to build an underquilt.
Maybe this stuff and a layer of 2.5 oz XP might work well together.
How much does this material weigh ??Nov 14, 2009 at 4:21 am #1545227
Question for those who are smarter than me (so for everyone),
If the insul-bright is combined with some other insulation, like 2.5XP for example, is their a benefit over the same insulation and a reflective mylar sheet? Does the little insulation on the insul-bright work so well that it justifies the weight over plain mylar in an application like that? Or are people hoping that the perforated insul-bright will create less condensation than plain mylar sheeting?
for use in a cozy how does this material compare to reflectex which has been widely used in that application? The only thing i can think of is that i wouldn't want to wear a reflectex hat!(in reference to the co-thread on insul-bright)
-TimNov 14, 2009 at 4:28 am #1545228
I'm hardly the expert, but my original thought was exactly what you mention… the thermal reflective properties of mylar, but needle-punched through with poly for good wicking/moisture transport.
I'm hoping to hear more from Richard on the 3/4" "air space" on each side of the Insul-Bright. I'm hoping that 3/4" of XP or down will be the same as that air space.
With a teeny bit of insulation on the OUTSIDE of the insul-bright as well, followed by the outside protection layer (DWR?) may end up with very good insulation without getting SOAKED. That last bit is the part I'm trying to avoid. ;)
I believe you did the write-up on the Cuben quilt/bag? That looks really really neat! I was looking around for Cuben fabric, but it looks tough to purchase.Nov 14, 2009 at 6:58 am #1545233
Still looking for a weight. Sounds perfect for a hammock underquiltNov 14, 2009 at 8:04 am #1545242
"for use in a cozy how does this material compare to reflectex which has been widely used in that application? The only thing i can think of is that i wouldn't want to wear a reflectex hat!(in reference to the co-thread on insul-bright)"
Quite a bit better – in a number of ways. Reflectex's biggest down side is the bulk. You cannot get away from that. It doesn't squash down – it will always be a big UL piece ;-) IB is very packable.
Reflectex is also more fragile and will abrade over time. While one needs to treat IB with some degree of gentleness it is a hard worker – that poly protects the mylar inside.
While it is washable by rinsing gently you cannot flip it inside out easily (if at all) and drying is another issue – you have to make sure you air dry or wipe it down after cleaning. With Insul Bright you can handwash with Woolite and air dry.
As well Relec. does not breathe, where IB does. This means that in relation to hot food the cozy will air out once the food is removed and self dry. If you get a very steamy meal in a Reflec. cozy you will have build up…which over a trip can equal smells/buildup.
Insul Bright is what truly made our cozies. The temp readings come back the same on both insulation's as well – so Reflec. doesn't have any advantage. I was quite happy when I discovered years ago how well IB worked for our FBC cozies. OTOH sewing cozies is a royal pain in the rear – I have sewn every single one, thousands of them, by myself.
That and ours have the advantage of being fashionable ;-) Hehheh!
The IB is on the inside, decorative fabric on the outside which protects it.Nov 14, 2009 at 8:27 am #1545247
Insul-Bright layered with 2.5XP and up oz/yd2 provides negligible benefit. Also reflective Mylar with 2.5XP and up provides negligible benefit. If there are five or more polyester fibers intercepts between the radiation source and sink, there is negligible benefit to the reflective layer.
I chose the term "negligible" rather than "no", because the exact crossover point for five intercepts is different in the various oz/yd2 options for each fiber-fill insulation type. The reflective layer adds value to Insul-Bright primarily because the material is only .12" thick and there aren't adequate IR intercepts.Nov 14, 2009 at 8:50 am #1545251
Ah! So the material for the insulation above the Insul-Bright would need to be IR transparent… does such an insulation exist? More importantly, would it be worth using?
4:30 p.m. –answering my own question… NO.
Once you've absorbed/reflected the IR with the insulation, it's kinda worthless to try to reflect it back to the source… so at this point, the Insul-Bright just acts as a NOTHING.
sigh…Nov 14, 2009 at 2:52 pm #1545323
I have a zipperless sleeping bag that has a layer of "silver lining" reflective insulation in addition to about 1" of polarguard. I believe that it's very similar to a mylar space blanket with holes punched.
It seems to be very hot when the weather is warm, not so much in cold weather. Even with the needle-punched grid and sewing holes, it inhibits vapor transport in warm weather (when I'm sweating). In cold weather I don't believe that it blocks enough vapor transport to act as a true vapor barrier.
Reflective heat barriers work best with large temperature differentials- like blocking the sun's heat (11,000 degrees).
After writing this yesterday I decided to cut it open and make it into a "quilt with footbox". The mylar material has a lot more holes than I thought. It's almost a mesh of tiny holes on about 1/16" spacing, stabilized by a fabric scrim.Nov 15, 2009 at 5:07 pm #1545482
@scfhomeLocale: Chocorua NH, USA
So does anyone have an idea how this material would compate to Insultex (idigear.com)when added to a quilt or sleeping bag?
Sam Farrington, Chocorua NHNov 15, 2009 at 10:50 pm #1545562
It would be even worse than placing an additional CCF sleeping pad on top of your bag. It wouldn't regain its thickness (insulation value) from being compressed in your pack plus it is unable to breathe as is the case for any CCF.
There are a large number of trade names for the same LDPE chemistry. It is not used for sleeping pads because it takes a set when you lay on it and it will not regain its thickness until as long as 24 hours later. Its insulation value, for a given thickness, is about the same as the Evazote yellow foam sleeping pads.
It is extremely light weight and is used primarily to make swim vests. Secondary uses include, canoe buoyancy chambers, body protection pads, and helmet liners.Nov 18, 2009 at 5:30 am #1546057
@scfhomeLocale: Chocorua NH, USA
Thank you for the information and insights. Alas, I am not up to speed with all the science and terminology. My interest stems from having to design and make my own sleeping bags, as I am only comfortable with a center (over the chest) zip, and I have not been able to find anything truly ultralight with syntehtic insulation. The bias toward synthetic inslation comes from several long hikes in damp, colder weather, where the moisture coming from my body dampened down insulation that then froze, rendering the bags useless. Not experiences I care to repeat.
Since I have to make my own bags anyway, I am interested in finding the most weight efficient layers to use.
Over the years, there have been a number of add-on products for synthetic layers. Early on, there was Texolite, a needlepunched foil sandwiched between scrim, as in the Yakworks Yaksack. At the time, there was a consensus that it was somewhat effective, albeit heavier than represented by the manufacturer.
Another approach has been to needle punch space blankets made of reflective mylar or polyehtylene materials, and this seems to be what is alluded to above, albeit with the conclusion that it is not effective.
So, what drew me to this thread is the possibility of using some other needle-punched reflective material like Insulbright, or a thin foam like Insultex, as an inner layer (sewed to the inner shell) with the more conventional synthetic insulation (choose your own – I don't want to get into that discussion, which can be endless) sewn to the outer shell.
What I understand you to be saying is that the Insultex, as thin as it is, nevertheless by taking a set when you lay on it, becomes ineffective when you roll over and need its full insulative value in the quilt or bag. Not encouraging, but the insight is very helpful, because I don't want to put a lot of effort into sewing it or Insulbright into a bag for nothing but a few ounces of worthless added weight.
Better to just add a little more thickness of the more conventional insulation of one's choice.
One other point is that the Insultex supposedly does breathe, in that it is represented by the manufacturer to allow water vapor to pass through it, but only in one direction. Credible? I don't know.
Thanks again. Am in the middle of a tent project this winter, so there is plenty of time to keep searching for the magic bullet to go into the next bag.
Sam Farrington, Chocorua NH
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