GG ThinLight R-value

3/8" = ~1.36
1/4" = ~.90
1/8" = ~.45

Richard's values seem reasonable. For reference, I have slept on top of snow, in a Sleeplight bag, with just a polycryo ground cloth and a 1/8" thinlight under my legs (Nightlight Torso under my torso), and found that it was fine.

Does anyone know the R value for 3/8 in. blue foam pads? Richard?

Zote Foams Evazote EV45CN (typical material used in backpacking sleep pads) has a thermal conductivity of .038 W/mK which gives it an R-value of R-3.8 per inch. This agrees with Richard's numbers to within about 10 percent. I expect blue foam pads to be pretty close to this, giving similar values for the same thickness.

To contrast Glen "Icicle" Van Peski's experience, I like at least R-3 under me for sleeping on snow. ;-)

Glen, Ryan, and some hardcore others seem to be able to get away with much less, so experiment to see what works for you.

Cheers,

-Mike

Blue foam is not as durable as GG's Evazote® nor as warm for a given thickness. Although all blue foam looks much the same, its quality varies widely. Squeeze the foam between your thumb and forefinger. Inferior foam will spring back slowly, if at all. The best available blue foam has 9% EVA content. The smaller the W/m K number, the more insulating the pad is. The average thermal conductivity, for the best blue foam, is .040 W/m K, whereas GG's Evazote is, depending on the sample, .038 – .039 W/m K.

As Mike said, the two types of pads 3/8” R-value’s are similar. The best 3/8" blue foam pad's R-value is 1.35. Using Mike’s .038 W/m K for GG Evazote yields a 3/8” R-value of 1.42 for GG’s Evazote.

Thank you, gentlemen. Very helpful.

Just as Glen stated, I'll just be using the 1/8" foam for under my legs (and maybe my arms). I'm using a Insul Mat Uber Micro for my torso. About the same weight as the NightLight Torso (Insul Mat is 3 1/2 oz) but not as thick (1 cm for the Insul Mat). With an R-3 rating for the Insul Mat I probably only need the 1/8" ThinLight just to knock the chill off from the ground.

Thanks for everyone's help. This has been the place to come to get my questions answered.

>>I have slept on top of snow, in a Sleeplight bag, with just a polycryo ground cloth and a 1/8" thinlight under my legs (Nightlight Torso under my torso), and found that it was fine.

Glen, as skinny as you are, how do you keep from turning into a popsicle?

> I am thinking seriously about purchasing the 1/8" pad.

I have used the GG ThinLight 1/8" pad with a quilt on the ground and in a hammock down to about +40F and found it warm enough. I usually add a torso pad for comfort, but I haven't noticed being cold where the only insulation between my bare legs and the ground was the GG ThinLight 1/8" and a polycryo ground sheet. YMMV, and I can't comment on its effectiveness alone on snow or below-freezing ground temps.

Doug,

If like these GG pads and if you want to push your quilt lower and eliminate any drafts check out the Down to Earth Pad Converter in the Spotlites.

Pan

>If like these GG pads and if you want to push your quilt lower and eliminate any drafts check out the Down to Earth Pad Converter in the Spotlites.

I am definitely considering that solution. I have been using my Jacks R Better Nest quilt for ground sleeping this year, and it's just a bit freezy when I roll over in the night (my chest/arm girth is 60") with a nice breeze blowing through my tarptent or cape. I was going to mod my Nest with the JRB Quilt Wings, but I may go with the Pad Converter instead since I always use a GG ThinLight anyway. The only extra weight is a bit of OmniTape, and the cut-down GG ThinLight pad would probably make up for most of that.

Doug,

Figure the assembled girth at 64 inces… so you it should fit nicely for you… The mod to your No Sniveller will add right at 1 oz; and the omni tape on the pad is a net plus of about 0.4 oz over a stock 1/8 thin light… the shaped 1/4 pads are below the stock weight even with the OT.

It is a significant plus up in warmth as there is no heat loss above the pad on body shifts as it is totally wrapped by the quilt….

Down side is you roll inside the "Bag" not with the "Bag"…no big deal for most, an easily learned and mastered technique.

Pan

>>Glen, as skinny as you are, how do you keep from turning into a popsicle?

I have low expectations ;)

The 1/8" GG pad was one of my first investments in "UL" gear. Just to be safe I also bought the thicker pad at the same time, I think 3/8" a few short months ago.

The 1/8" has done it for me, in all circumstances above 40 F temps and even in snow conditions that were "mild." Keeps my lower legs protected and warm and doesn't weigh anything to speak of, like 1 oz.

And, it reaches far enough that I not only use it as a vapor barrier and leg base, but it extends just up over the end of the torso pad far enough to serve as a base for a UL inflated light weight pillow at a fraction of an ounce. So, I would highly recommend experimenting with the 1/;8" to find out what fits you. I love it.

So the thermal R values are new to me, but it works in snow if you have your sleeping gear together and the accomodations … so I think it is an operator controlled outcome whether the 1/8 " works for you.

Has anyone found a source for a 1/8 inch pad similar to Gossamer Gear’s thinlight pad, BUT in wider sizes? TIA

Brendan

I’ve just talked with a couple of foam fabricators in the UK with a view to organising a UK group order, as the cost of re-importing the GG product is prohibitive.

According to one supplier it would normally be sliced from an Evazote block 1 meter wide and 1.5 or 2 meters long. So in theory you should be able to source a pad that’s up to 1 meter wide. But good luck finding a supplier, as they are going to want to sell you the whole block, which would make 9 pads @ 1 meter wide (or 18 GG-sized pads @ just under 500mm).

If you do take this route, the Evazote grade you are looking for is VA35. VA refers to the level of vinyl acetate copolymer in the blend, and 35 is the weight of one square meter in kilos.

I believe the “InsuLite” EVA pads that Lawson sold a few years ago were 24″ wide (GG’s is 19-3/8″).

If I recall, he ran into sourcing issues and stopped selling them, but you might try to reach out to him to see who is original contact was. Perhaps there’s another retailer somewhere.

Yes, but shipping is often very pricey. For example there is this place: https://www.foamorder.com/foam/closed-cell-foam.html

I found a local foam place, but they charge a lot as well, presumably because of shipping costs, though I imagine they ship in bulk and save some money over small quantity shipping.

Your best bet might be the interloacking EVA foam “tiles” or “puzzle pieces” that are often sold as exercise matting. For example, you can get 24 square feet of .5″ foam for around 20 dollars including shipping on sites like Amazon!  Each square is typically 24″ X 24″. An example is:

If you like to store your foams on the outside of your pack, they might present a bit of a challenge though if you want to roll it up and use the under straps (course there are ways around this, but require some thinking and a little DIY).

Another factor to consider is density.  I’m not sure what density that foams that GG and the like are selling. You’ll want a certain density to get a balance between durability, comfort, and weight.  2 lb/cu3 might be too light, too squishy and not durable enough and 5.8 lb/cu3 might be a bit over firm. I imagine density also affects the R value some too?  I would assume as the density goes up, R value probably goes down a little per given thickness?

Justin

If you want a useful pad as thin as the GG ThinLite, I suspect that Evazote is pretty much the only way to go.

As I posted above, a UK foam fabricator with a strong relationship with Zotefoams tells me that the ThinLite will be using EvaZote grade VA35.

The fabricator has a lot of experience with the cheaper Plastazote and in their view it isn’t robust enough to work with such a thin pad.

I thought the EVA part was short for EVAZOTE foam?  Aka “ethylene-vinyl acetate, also known as poly, is the copolymer of ethylene and vinyl acetate”?

Both the links I shared either had options for or directly linked to EVA type foam. I agree it’s superior–not only in durability and apparently slightly in R value, but also in UV resistance. It’s one of the few common consumer available foams that can handle a lot of UV well. Important for outdoor use.

Justin –

I’m no expert, but I think Evazote is produced by a proprietary method. There are other foams using similar materials, but I’ve never seen it claimed that they are the same quality.

The advice I was given (by a company that makes a wide range of foam sleeping mats) is that Evazote was the only foam that would be robust enough for such a thin mat in a lightweight 30k formulation.

I’m not an expert on this matter either Geoff. There may be some difference as to quality between official Evazote brand EVA foam and other EVA foams, but I can’t imagine with a similar or same base materials that this difference would be tremendous.

An analogy might be something like the difference between Dyneema or Spectra brand highly oriented UHMWPE fibers vs less expensive Chinese versions. Yes, the latter tend to be a bit less strong and durable than the former, but they are still remarkably strong and durable compared to other different materials.

Corporations and marketeers are always trying to convince us, and often not very honestly, that their product, their material, etc is far superior to another’s similar or same product or material. Sometimes there is some truth to such claims, but there are plenty of times when it’s mostly marketing spin, especially as to “claimed proportion of difference”.

I tend to be somewhat skeptical in approach, especially in relation to any endeavor that potentially involves profit and/or greed factors.

I’ve bought “off brand” or non Zotefoam brand EVA foam before and it seemed durable enough.

Not considering the brand:  “Plasta” (or blue or primarily cross linked polyethylene) type foams vs EVA foams do have some noticeable differences in durability.  They are different kinds of foam with different chemical makeup.  As Richard N. noted earlier in this thread, blue type foams or what Zotefoam company calls their Plastazote foam line, have a much lower EVA content than EVA labeled foams.  The EVA part is primarily what increases the durability/strength, greater UV resistance, and slightly higher R value.

Perhaps someone like Richard N., with more knowledge on the matter can help to correct any of this if it’s off?

Haha,  I think you guys made it in the ‘ultralight jerk’ Instagram post!

https://www.instagram.com/p/BiB-fYEltLq/

I thought the same thing when I saw that this morning.

“Comfort is not an issue, but warmth is.”

My 1/8 inch pad weighs 2.8 oz in the 60 inch by 19 in size. it has its uses but a standalone Sleep Pad is not one of them. As a supplemental pad yes. As an emergency stand-alone pad yes. As A pad for taking breaks in the daytime on ground covered with uncomfortable pointy things, yes

Up to you but sleep is not somewhere where I consider skimping on comfort or warmth. It’s your refuge and rejuvenatuon at the end of a long hard 25 mile day. When you have another long hard 25-mile day to do tomorrow. And the next day. And the next day.