Evazote Pads – why?

[Philip Maynard]

I sent this email to MEC a while ago and got no response. Has anyone noticed this before? Everyone raves about Evazote, but the numbers don't add up. Granite Gear's numbers make the pads sound much better.

I was thinking about getting one of your Evazote foam pads. However, looking at the specs, I'm confused. The 1cm Evazote pad is an R-value of 1.6, so warmth per thickness is R1.6/cm. But the other two thicnkesses, 0.5cm (R0.66)and 1.5cm R2.06), are both ~R1.35/cm. Is one of those in error?

Looking further, I noticed that the Evazote pads are very heavy – 175g for the very thin Bivy pad. At 220g, the Blue foam pad offers an R value of 1.36: twice the warmth, and only 25% more weight. Two blue foam pads would get me an R-value of 2.72, at 2cm thickness, and only 440g. The Winter Evazote pad is over 2x the cost, 525g, and only R 2.06.

So, what do the Evazote pads do? I always hear that it's some kind of great material, but they just appear to be heavy, cold, and expensive. They are somewhat warmer for a given thickness, but a cheap Ridgerest or self-inflating pad beats them handily there as well.

Further investigation showed that Granite Gear sells Evazote pads with 1/2 the weight per thickness. Thier 150x50x0.95cm pad is only 156g, to your 1cm pad's 350g. This makes me wonder if your numbers are right, because while they don't offer R-value data, they claim that Evazote is 1/2 the density as your specs show.

[James holden]

they dont add up … i did a post on it a while back … evazote is mec yellow … i was told they are more durable than the mec blue

unless im missing something … i suspect its a matter of one climber telling another climber that evazote is better … and no one actually testing the R values … i think mark twight (or was it mr conelly or kirkpatrick) recommended evazote way back …

ive had one or two people tell me that reflectix is the best … not the case at all … lol

reflectix is listed as 1.25 oz/ ft2 … so 11.25 oz/ yd 2 … for an R value of 1.1 if we accept the manuf claim … which is an R per oz/yd of 0.097

the mec blue standard 9.25 oz / yd if my math is correct … for an R value of 1.36 .. R per oz/yd of 0.146

the mec yellow standard 13.75 oz / yd if my math is correct … for an R value of 1.6 .. R per oz/yd of 0.116

the yellow thermalest zlite is 12.93 oz / yd 2 … for an R value of 2.2 … giving and R per oz/yd of 0.17

the RR Solar is 17 oz / yd 2 … for an R value of 3.6 … giving and R per oz/yd of 0.21

[David Olsen]

Unless you know the density, you are comparing apples to oranges. Density effects
strength, compression resistance and longevity of the material. Evazote is a light
for warmth material as are other brands of Zote foams.

[Steven Evans]

Evazote is the name of the product line, which then comes in a number of different models with varying density, compression, thermal properties, etc. You can get very dense and "heavy" evazote or very light evazote like the stuff sold by gossamer gear. All the products mentioned above could very use evazote in their product but just a different model.

Think of it like cuben fiber – it comes in a wide range of weights. You need to know the specific model number to get any real characteristics of the material.

[Daryl and Daryl]

Philip,

I feel your pain. These numbers frustrate me too. I only have a fragile understanding of all this insulation, clo, R-factor stuff and inconsistancies like you have pointed out are frustrating and confusing to me.

On this subject, Insultex claims to have a clo factor of 2. It also says it will keep one warm to 13 degrees below zero. What? This stuff is .5mm thick (about 1/50th of an inch thick). I'm experimenting with it now. Just looks like a fragile piece of very thin foam like you might find wrapped around somthing that was just shipped to me in the mail.

Here's the link to further confuse the issue. What do you think of this clo rating?

insultex

[James holden]

the mec yellow standard evazote pad weights 350g and provides a R of 1.6

the zlite weights 410g and gives an R value of 2.2, it is however 183 cm vs. 150 c, for the mec yellow and is 51 cm vs. 50 cm

if you cut down the zlite to the same length it would weight ~340g and give an r value of 2.2 … so both warmer and lighter for the same area

thats all anybody needs to know to use it … no need to make things complicated …

now there may well be other evazote pads that other people use … but do you really know the R values accurately?

[Ewald Heersema]

Hi all, I’m the Technical Business Manager for Zotefoams – maybe I can be of help.

The weights for the pads as indicated on the Mountain Equipment Co-op website are correct, as are their claims on durability and how they are made.

The Zotefoams Evazote® Standard Sleeping Pad and the Zotefoams Evazote® Bivy Sleeping Pad are made of the same high durability EVA polymer.

The Zotefoams Blue Foam Sleeping Pad and the Blue Foam Long Sleeping Pad are made at a lower density; true to the description in the catalog. The pads are made of a different polymer as well and are not as durable as the Evazote® pads.

The R-values are a function of density, thickness, and polymer.
The consistent R-value indicated for the Blue Foam Sleeping Pads are because both sheets are of the same density, thickness and polymer – the TC factor for this particular polymer at this density is 0.2732.
The R-values indicated for the Evazote® pads is different, as they are made of a different, more durable, polymer. I have to say that the R-value on the Standard Sleeping pad is slightly overstated but could very well be a rounding error. The Bivy Sleeping pad value is correct. The TC factor for this polymer at the higher density for this mat is 0.2801.

I believe that the reason come people are so pleased with the Evazote® material is that the shear and long term durability characteristics are really superb. The material has proven itself on expeditions to Mt. Everest and for decades by users worldwide.

Ewald Heersema
http://www.zotefoams.com

[Mikael Akke]

Ewald, could you please comment on the pros and cons of Plastazote compared to Evazote? I've seen some vendors offer pads made out of P as a lighter alternative to pads made of E. I understand that E should be a bit more durable, but what about weight vs R-factor, etc?

[mike parsons]

I invented the Karrimat in 1968 using Plastazone and shortly thereafter with Evazote which was produced in yellow (specifically and exclusively at that time) for me at Karrimor; Karrimat is now a generic term for closed cell mats in several Euro countries but was the reg;d T M of Karrimor in the UK of which I was then part owner and the key designer.
1968 was very shortly after the invention of the material, in UK which to my knowledge is still the only place where its made. Although the unique mfg process is lengthy and more expensive than other foams made by extrusion processes, zote foams have maintained their position because of higher performance.
Plastazote is polyethylene (or polypropylene?) and has less rebound than Evazote which has vinyl added to the long polymer chain.
Evazote has better compression recovery, tear resistance and ( subjectively) feels slightly warmer because your body sinks into it ever so slightly. Both are available in a range of different densities, Karrimat ( from memory) was always 45kgs.
The original process for making these closed cell foams was ( and probably still is) a lengthy, ie more costly batch process like making a loaf of bread. The rectangular hard plastic pieces were placed in a pressure chamber and Nitrogen pushed into it in gaseous form, after that the 'bun' was then placed in an oven and the gas emerged as distinct unconnected bubbles ( hence 'closed cell')
This bun was around 30mm thick and had a skin around it and was then sliced into different thicknesses, leaving the outer surface cells open, which cld be sealed if necessary.

Hope this adds slightly to the understanding, however I cannot at this precise time talk definitively about comparative R values but in due course will do so within the new book a team of 7 are working on, (6 in UK one in USA)
"keeping dry, Staying warm; through all activities over 7 continents"
http://www.outdoorgearcoach.co.uk/

[Max Dilthey]

Incredible, the representative from Evazote and an inventor… Only on BPL

[Greg Mihalik]

I appreciate the answer, and the source….

….but to a question posted 3 years ago?

I'm fascinated by what transpired to make it happen.

[Mitchell Ebbott]

[Bob Gross]

It is amazing what a Google search can inspire.

–B.G.–

[Anonymous]

Mike, the book looks fascinating. Hope you cover Paramo a bit in same? I have limited experience with it, but i'm fascinated by the concept of it and more over by the extreme polarization that seems to crop up among people that know about it… (many people either seem to LOVE or really DISLIKE it). I feel like Americans like myself should at least be more exposed to it.

[Geoff Caplan]

Just spotted this thread and the historical background from Mike Parsons.

I was one of the very first to have a Karrimat pad. It was a prototype, in white foam, quite badly pitted and irregularly shaped.

I knew Graham Tiso in Edinburgh and he was outfitting an Everest expedition. Mike had supplied the pads for them to try out, and Graham had a few that were surplus to requirements so I managed to blag one.

Before that we were using piles of heather, or heavy and cold air mattresses.  It was a huge step forward.

I still have it and it’s still usable, half a century later…

[James Marco]

Some pads are sealed at the surface and/or molded with limited heating similar to this: https://www.thermarest.com/z-lite
Others are simply sliced from a billet like the GG NightLights. https://www.gossamergear.com/collections/sleeping-pads/products/nightlight-sleeping-pad-torso-length
The older NightLights were just sliced and very light…around 6 ounces for a 68″ pad.

Heating, chemical treatments to the surface, adhesives all add weight while reducing the actual R value. There is a huge difference in CCF (closed cell foam) pads. Starting at the base materials right up to post processing surface treatments. Often, manufacturers include dimples in R values. Some do not (like the older GG pads.) The big thing about a CCF pad is it always works. There is no inflatable component to worry about leaks. Some are not really durable and get scraped and dinged up easily. Some do not take compression well. But, they always work. They do NOT lend themselves to “inflation” techniques like the Guidelite or Ridgerest series. You need an open cell foam for that. They are not as comfortable as thicker 1.5-4″ pads, but I usually carry a folded Evazote pad and a Neoair. This insures I will usually sleep comfortably and warm down to about 20F. Warmer/dryer temps require less, leaving the neoair behind. Colder temps might require more. But overall durability is very good, I have used some version of a CCF pad for around 40 years, electing to simply pile up forest duff before then. I still have an old military CCF pad around…actually two.

[Matthew / BPL]

Slight thread drift but I’m wondering if anyone has had success using a hot knife to score a 1/4″ thick GG pad for folding. I’ve got one of these left over from a failed attempt to keep my wife warm in a hammock that I’m thinking about chopping up.

[Eric Osburn]

Does anyone make a thin, light pad that doesn’t pickup a ton of dirt, pine needles, etc?

 

I’m currently using a z-lite pad that’s cut in half as a backup sleeping pad, pad to pop next to my shelter to keep stuff from getting muddy, sit pad, etc. I like that it stays fairly clean. It’s about 200g and one if my luxury items.

[Author]

Posts