eVent drysuit

-- Last Updated: May-13-09 1:22 PM EST --

eVent gets favorable breathability reviews vs. G-tex in jackets and I see NRS has a new drysuit made with eVent. It's probably too new to seek user comments so just seeking advice from those who may have researched it a bit. Of course, the WB aspect of a drysuit is only one thing to consider. The overall construction, seams, quality, zippers, gaskets, fabric are all important no matter what WB application. Kokatat construction might be superior to NRS brand, albeit at a steeper price.

I’ve had eVent garments for years, but
I can’t say I am able to tell the difference from my one Goretex drytop in actual use. I think the ones to ask are the touring and sea kayakers. Us whitewater people get so drenched outside that we can’t always tell how well the inside is being vented.

Plus and minus
EVent has the advantage of trmsmitting water vapor directly gore-tex water must condense first and move thru in liquid form. So in low humidity situations where the user is hot and sweating allot it can be dramatically more breatheable.

However in kayaking it may not be significantly better. Also may be early to see if eVent is as durable as a drusuit and if the construction of the suit and warranty are on par with kokatat

a faucet that flows both ways?
No, gortex works by passing water vapor. If the vapor had to condense into a liquid, then it would not stop liquid from the outside from coming the other direction.

I like eVent. Only problem I’ve had with it is I get cold. I only wear drysuits in cold weather, as I’ve never trusted WB fabrics to keep me comfortable in warm weather situations.


– Last Updated: May-13-09 10:32 PM EST –

please take in best way. I thought the same as well. Gore-tex itself has been less than clear about this fact. Original gore clothing did but it got contaminated by sweat. They had to add a PU layer. Gone was the vapor transit. They have improved their product transmission rate and in humid environments the difference between the products is not as much. and imo gore product type used in Kokatat is close to as breatheable. What we don't as yet know it the quality of the eVent garment.

But, no it does condense. Really.

eVent discovered what Gore did not, how to remove the PU layer and not have the contamination. This means that in a gore product the layer of air between the body and jacket must warm up, get to dew point of saturation first condense on PU layer and then be transported thru to outer layer.

Thus eVent is quicker in some conditions than gore because the vapor starts thru right away and it does not need to change state.

Sorry, but you’re wrong
Water does not have to condense to pass through Gore-Tex, it passes through as water vapor. What you’re describing is a wicking action, which is not how Gore-Tex works. As Nermal pointed out, condensed water WILL NOT pass through Gore-Tex. Here’s a link that explains it:


Click on the subheadings for details. The pertinent passages are:

“The microporous structure of the GORE-TEX® membrane is what makes GORE-TEX® fabrics completely waterproof. Each microscopic pore is about 20,000 times smaller than a drop of water, which means no external moisture - from rain to snow to that puddle you just stepped in - can penetrate the membrane.”

“The pores in the GORE-TEX® membrane are 700 times bigger than a water vapor molecule, so perspiration can easily evaporate through and you can stay dry from the inside out.”

Be Prepared to Be Shocked About Gore-tex
Be prepared to be shocked about how Gore-tex and other products work. It is a cautionary tale of manufacturer’s claims and the actual scientific real world performance with advertising that is less than accurate and possibly misrepresenting.

BynstromI know you have tons of knowledge, so totally respectful.

I too had this take on it for years. And I am a tech head of sorts as well.

I think the science paper will surprise you, it certainly did me!

I found the link

Waterproof Breathable Fabric Technologies: A Comprehensive Primer and State of the Market Technology Review by Alan Dixon, Ph.D. (MIT)


IMO what remains to be seen is how eVent holds up in marine environment, and whether in conditions we face it is superior to XCR and the specific formulation that Kokatat uses.

Good reading and best regards


Small part of article follows

How Gore-Tex Really Works (The Answer May Surprise You)

First we’ll cover Gore-Tex, the (aging) granddaddy of all waterproof breathable membranes. More than 25 years ago, W. L. Gore created a thin membrane of expanded PTFE (a.k.a., “Teflon”; with a physical structure akin to a filamentous web). This membrane was waterproof but let water in gas form pass through (a micro-porous membrane). Presto, a waterproof breathable membrane!

How does it work? The common myth is that the spaces between the PTFE filaments are large enough to let water in a gas form pass through, but small enough to prevent water in liquid form to pass through. This is not exactly true. In fact, there is plenty of room for liquid water to pass through the spaces between the PTFE filaments!

More correctly, the surface of the PTFE membrane is at a high surface energy level (in lay terms, this means that it is extremely water repellent, or hydrophobic). Water in liquid form is repelled with such force (resistance to capillary wicking) that it takes a great deal of pressure to push it through the PTFE membrane. Water at a pressure resulting from a heavy rain doesn’t begin to reach this level. Conversely, if something were to take the membrane’s surface to a lower energy level, the water repellency would be lost and water would pass through the spaces between its filaments via capillary wicking. This is “first generation” Gore-Tex fabric and exclusively relies on the hydrophobicity of the microporous membrane for its water resistance.

When first generation Gore-Tex appeared in rainwear, it worked great - for awhile. However, customers began returning garments that had begun to leak. Here’s what happened: body oils, detergents, dirt and other common chemicals contaminated the PTFE membrane from inside. The membrane’s surface was initially effective enough to repel water, but it couldn’t repel these contaminants. Contaminant adsorption to the PTFE surface decreased its surface energy, creating pore channels with poor water repellency that wicked moisture through the membrane’s structure - not exactly the functionality you want in a waterproof garment. The result: the garment leaked. (It is worth noting that a fully expanded PTFE membrane can have an air porosity as high as 80% - so there is plenty space between the filaments for water to wick.) Thus, both surface energy as well as pore size are important factors affecting the waterproofness of a membrane. Gore learned the hard way the consequences of failing to recognize the long-term consequences of contaminant fouling of expanded PTFE.

Gore engineers tried to design a technology to keep the membrane free of contamination. The result: cover the PTFE surface with another membrane to protect it from contamination. The choice for this second membrane was polyurethane (PU). But how was water vapor to get through the fabric, since the pores of PU in its natural state are not large enough to be permeable to water - in either liquid or gas form?

The trick was to chemically modify the PU to be water absorbent (hydrophilic). Water in gas or liquid form is adsorbed by the PU membrane when it comes in contact with the membrane’s surface. Once adsorbed to the membrane surface, individual water molecules are then transported via solid state diffusion to the outer surface of the PU membrane. Diffusion is a chemical process where a substance at high concentration is transported to a region of lower concentration. In the case of solid state diffusion of water through a PU membrane, individual water molecules in their liquid form (H2O) creep their way through the PU matrix, driven by the concentration gradient formed by a high concentration of water on the wet inner surface to a low concentration of water on the dry outer surface. Once the water molecule reaches the outer surface of the PU membrane, it can then evaporate (become a gas phase molecule) and transport via gas phase diffusion through the PTFE membrane. It is important to note that the PU membrane is solid (monolithic). There are no spaces for a gas or water to pass though it. Water in either gas or liquid form is transported on a molecular level through the solid PU membrane (solid state diffusion). We refer to this type of PU membrane as a hydrophilic monolithic membrane.

So far so good. Gore had prevented contamination and they engineered breathability in the form of water molecule transport by solid state diffusion thought the PU membrane. Now the real problems start: the solid PU membrane moved water at a rate significantly less than the original PTFE membrane it covered! Thus, Gore made this membrane as thin as possible (see durability issues in the next paragraph), achieving a level of performance that was sufficient to bring the technology to market and they marketed Gore-Tex with its new PU membrane protection. This use of a hydrophobic micro-porous PTFE membrane covered by a PU hydrophilic monolithic membrane is often termed “second generation” Gore-Tex. Gore has made improvements in both weight and breathability relative to first generation Gore-Tex with the development of fabrics such as PacLite III and XCR, but they still employ the basic PU-PTFE membrane technology used in second generation Gore-Tex.

One final issue: PU-PTFE Gore-Tex membrane was delicate, resulting from an ultrathin PU layer, and had to be protected. Wear abuse causes pinholes and cracks to develop in the membrane and create leakage channels. Protection for the Gore-Tex membrane was accomplished by either adding a free hanging nylon liner on the inside of the garment or (more commonly used nowadays), by laminating a protective layer of polyester tricot to the inner surface of the garment. The latter type of construction is used in what is commonly known as “3-layer” fabric. Typically (unless laminated to an extremely light face fabric), three-layer fabrics are bulky, heavy and compress poorly. Gore’s 2.5-layer PacLite III mitigates some of these problems by substituting a textured surface pattern on the inner face of the WP/B membrane in lieu of the heavier and bulkier tricot inner liner.

eVent How does it work

What if you could use the original expanded PTFE membrane and not have to cover it with a PU membrane? You’d have a waterproof breathable membrane that would move moisture approximately 30% to 200% faster than Gore-Tex XCR*. BHA Technologies has developed such a membrane, branded as eVENT. Sounds like first generation Gore-Tex, doesn’t it? Here’s the difference: BHA engineered the PTFE membrane to be oleophobic, and thus, highly resistant to contaminant fouling. The eVENT PTFE membrane repels most of the common oily contaminates that originally plagued the first generation Gore-Tex membrane. Thus, eVENT does not need a breathability-inhibiting PU membrane to protect it from contaminants.

With unimpeded spaces between fibers (a micro-porous membrane), eVENT’s moisture transmission behavior is more like an uncoated woven or knit fabric. From Figure 1, you can see how closely eVENT matches the performance of Schoeller’s Dryskin Extreme, a stretch woven fabric that has no WP/B membrane (note that the air permeability effects of a fabric on moisture transport are eliminated in this test; if air permeability is considered, much higher moisture transmission rates would be measured for Schoeller Dryskin Extreme).

eVENT’s membrane structure is important in two ways. First, molecules in their gaseous state (including perspiration vapor) can pass through the pore channels between the membrane’s fibers, a process that is capable of moving significantly higher fluxes of moisture than what is possible for by a solid layer of PU (as in Gore-Tex). Second, and more important, eVENT passes moisture equally well at both low and high humidity levels, evidenced by the independence of eVENT’s moisture transmission rate on the humidity level (see Figure 1). At a 70% mean humidity level, eVENT transports moisture about 30% faster than XCR and about 70% faster than standard Gore-Tex and the best PU membranes. But at a 30% mean humidity level, eVENT transports moisture about 200% faster than XCR and about 250% faster than standard Gore-Tex and the best PU membranes.

Bnystrom is correct
Water moves in the liquid phase across the inner polyurethane membrane of Gore-tex but must be in the vapor phase to move across the PTFE membrane.

Anyway, since eVent doesn’t require the internal polyurethane membrane, it passes water vapor much faster. There is a nice quantitative comprison here:


And an entertaining bubble demonstration here:


I think the NRS eVent drysuit looks like a great idea, assuming the taping and construction is done well.

Why it is slower

– Last Updated: May-14-09 2:34 PM EST –

You are agreeing with me. The PU is solid state diffusion. The ptfe membrane really becomes only a support for a thinner PU layer. The big deal is the PU makes it slower in most condtions. This matters.

I thought Bystrom felt there was NO change to liquid I.e. That gore-tex allows for straight thru vapor transmission as actually only eVent does.

He says it works by gas. But only the ptfe part does.

feedback on the eVent dysuit…
I had the NRS eVent drysuit last season and I have mixed thoughts about it. Initially it was a great suit for me being extremely comfortable and dry. It has lots of well thoought out features like the suspenders, the cordura reinforced seat and knees, etc. With that said, after a particularly good whitewater session with lots of surfing (submerged arms under pressure), I found that my sleeves were no longer repelling water but rather taking on water through the fabric.

I called NRS for a replacement but unfortunately they were backlogged on this drysuit so I returned it and bought a Kokatat GMER suit since I couldn’t wait 3 months for a drysuit. The NRS rep said it was the first return that they had seen so hopefully mine was just a fluke. I do love my Kokatat suit as it fits my body better than the NRS suit which actually put me in between the size ranges.

thanks and couple of questions
Thanks. I am usually not a 1.0 gotta have it person, but eVent is a dramatic improvement so I was very curious if they have it down yet.

Maybe too early to tell. I could have gotten contaminated and actually failed or it could have had the same problem all breatheables have, i.e., wetting out due to inadequate DWR coating. Did they tell you what happened when you returned it?

What as the inside of the suit like, what i mean is the inner face of the material. Was it lined i.e., a two layer material?


eVent could react to contaminants
I think tideplay and bnystrom are both correct, in that water moves in liquid form across one ply of Gore-tex (the PU membrane) and in vapor form across the other (the PTFE membrane).

It is interesting about the loss of water impermeability with your eVent drysuit- I wouldn’t be surpised if the eVent PTFE membrane might lose its impermeability to liquid water after exposure to contaminants in water like oils and detergents (and herbicides like Roundup etc), which might be present in a lot of river water.

yes could be and yes, not who is right
yes, it is never a matter of who is right, only wanted paddlers to know Gore is making some overblown claims which we should always be aware of any company doing really.

The fact PU membrane is there is something they are not wishing folks to realize, especially as there are a number of alternative fabrics that will be very effective and cost less.

yes, the eVent could be contaminated. But, I would lay odds on that it is not yet being manufactured in the best way and mated with the fabric and DWR outer layer. In any eVent hoping they work it out. We could all profit from a drysuit that would be dry and comfy in even warmer conditions.

I think its 2 layer…
The inner layer was the standard nylon (or whatever) backing. I didn’t really follow up with NRS about what happened since I just exchanged it. The sleeves could have delaminated due to contaminants in the manufacturing process or the water I was in but both reasons are unacceptable when you’re paying nearly a grand for it and the primary purpose of the item is to keep water out. I still love NRS though and I will keep buying their stuff in large part because of their customer service. I am still hopeful about eVent and I’m currently using the SeatoSummit eVent drybags which purge air through the membrane. They’re pretty slick.

very contaminated actually!
You guys make a good point about water contaminants and while I think a suit should be able to deal with these things without failing, that’s definitely what could have happened in this situation. The river I was on is notorious for farm runoff and I wouldn’t be surprised if my kayak melted along with my sleeves. :slight_smile: