Mountain hardwear airmesh: Active Mesh Teijin Octa midlayer

[Marcus]

As usual Stephen, you’re the most scientifically factual member on the forums right now and I love it. Thanks for the data on Alpha CFM and all the data you generate and report.

Here’s a riddle for you – would an alpha double layer 60gsm be warmer than a single layer 120, as your fleece research showed loft height was the main factor driving warmth and my guess is 2×60 is thicker than 1×120. any data to support or contradict that?

[Stephen Seeber]

Marcus:   You can get data on that question in this article.  Happy reading.

[Daryl and Daryl]

Russ,

“Exerting energy, I sweat. As minimal as I can get with low temps, my base layer will be soaked.

Some folks at the gym just glisten…me, I drip in profusion.”

Me too.

[Roger Caffin]

As minimal as I can get with low temps, my base layer will be soaked.
Forgive me, but … The mind boggles.
WHY are you wearing a base layer under those conditions???
Why not take the base layer off?

At any temps above 0 C, Sue & I just wear our Taslan smocks. We don’t need more. We make our own warmth.

Cheers

[Metamorphosis]

Stephen,

Were you using Patagonia Cap Midweight and MH AirMesh as base-layers in the above comparison? Would layering MH AirMesh as a mid-layer over Brynje mesh layer (as next to skin layer) work better with wicking/warmth and potentially be a more versatile system especially for cold weather backpacking wherein I tend to sweat a lot?

Thanks for all your research!

[Stephen Seeber]

Hi Met:

I used an old Pat Cap Midweight for the comparison.  Based on the weight comparison between the two garments, they behaved as expected.  The heavier Pat Cap can be expected to have more capillaries which would explain its better wicking performance.  I returned the AirMesh after I tested it.  I do have a Noronna Octa Jacket.  I just applied water drops sized at 50, 100 and 200 ml.  In each case it was very slow to wet.  I don’t know if the chemical treatment for the Octa in this jacket is similar to the MH version, so it is not clear that the MH will wick well.  It certainly wicked poorly in my original test and poor wetting would also help explain the mediocre wicking performance of the AirMesh.  Answering your question about use with a Brynje mesh would require a better understanding of the MH Airmesh.  I would need to measure air permeability and do some more drop tests on the Airmesh fabric.  I use Brynje constantly and am very pleased with it.  However, I always wear Alpha Direct over it.  It is unclear to me what using Airmesh over the fishnet would bring to the table.  This is a topic I will discuss in greater detail in an upcoming base layer article.  Stay tuned.  So, I am not really answering your question but I may pick up another AirMesh up and take a closer look at it.

[HkNewman]

Handled the Airmesh at REI the other day yet again (should I buy?  should I buy?) .. and really like the dark versions.  Then moving a bit I realized it was pretty easy to see through to the other side with all the air holes in the fabric just holding it up by the shoulders.   I can see it when exerting oneself hard but no way that’s keeping anyone warm once stopped for a bit.

[Metamorphosis]

Stephen,

Thank you for your response. I look forward to reading your findings on base layers.

My main predicament is: I generate a lot of heat while hiking (I mostly hike in the White Mountains). In winter that poses unique challenges with moisture management, especially in negative temperatures. I have tried minimizing layers. But, sometimes a base layer (Brynje mesh) and wind shirt (BD Alpine Start) combination is not enough warmth wise. But, an addition of either a 100 weight micro fleece or a lightweight vest is too much. I tried Rab Alpha Flux, but was not impressed with how wet the fabric remained all day. Alpha inevitably also snagged frequently while passing in close proximity with snow loaded branches. Hence when I saw AirMesh at a local REI I was intrigued because of its smoother outer surface (less snags?), including potentially better wicking ability as a mid-layer. Given its loose fit, I can’t wear AirMesh as a base layer. Your experience however seems to suggest it is not an efficient wicking layer. So the search continues for that enigmatic mid-layer!

[Stephen Seeber]

The Alpine Start has good MVTR.  However, at temperatures below freezing or below dewpoint, vapor will condense on the interior of the alpine start and not escape.  If the insulating layer is also below dew point, the vapor escaping from the skin may condense in the mid layer and n0t escape either.  These conditions endlessly raise relative humidity within the space between the Alpine start and the midlayer or, if no mid layer is present, the fishnet, forcing condensation to occur.   This will produce the result you are experiencing.   You must provide additional ventilation to your system to let water vapor escape.   You need to have pit zips in the Alpine Start and use the main zip as needed to provide an exit for water vapor.  At high level output with low winds and temps of teens to to 30F I wear a bike jersey  with about 200 CFM/ft2 of air permeability over my Alpha Direct/Brynje.    This controls excess cooling from low winds or air flow from forward motion.   As I warm up in those conditions, I will often remove the bike jersey to enable more vapor removal.  I will only use a wind layer when the wind is blowing cold enough to require it or the air temps are well below 20F.  My wind layer has pit zips and I also adjust the main zip, cuffs, etc., to help provide mechanical ventilation.  With this system, I almost never accumulate significant moisture in my clothes.  During ascents, I maintain a high MET level of 6-8.

Concerning the Alpha Flux.  It is a misuse of Alpha Direct.  An Alpha Direct mid layer should be made only of Alpha Direct.  The flux exterior is a polyester or nylon shell fabric.  This will dramatically reduce air permeability and MVTR of the interior alpha direct.  My Alpha Direct layers (I have two different shirt type garments) are made of either 1 layer of 60 gsm or 2 layers of 60 gsm.  I  hike in the 2 layer 60 gsm of temps are going to be in single digits. Warmer than that, the 1 layer 60 gms is used. If you are wearing the Flux, you have not experienced the performance that can be achieved by Alpha Direct.

 

[Metamorphosis]

This is super helpful! I will have to experiment with a bike jersey now.

You have convinced me that Alpha Direct is a better option as a mid-layer vs. AirMesh. However, given the difficulty in procuring an Alpha Direct garment, what are your thoughts on Norrona Lyngen Alpha90 Jacket as an alternate? It has Alpha Direct on the core areas, and Polartec Power Grid on the rest. Personally, I find a full-zip garment more versatile.

[YoPrawn]

One of these days, I’m going to invent a mid-layer/base-layer with a thermostat knob* on it.

No zipping or changing of shirts, just adjust the temp right on the fly. Would be possible, but at what cost in weight?

 

 

*thermostat knob may or may not actually adjust temp, but it will technically have a knob ;)

[Roger Caffin]

a thermostat knob
Sometimes called a zipper pull.
Other times it is called ‘removing a layer’.

Cheers

[Metamorphosis]

Stephen’s reply also got me thinking about simplifying my outer layer and perhaps carrying just one instead of two separate wind and rain layers. Given that my wind-layer does not have pit-zips, and I am not aware of any wind-layer currently in the market that do either, would I be better off bypassing a wind-layer (such as BD Alpine), and instead opting for Montbell Versalite Rain Jacket? From what I have found reading up online so far, it seems very light, breathable, and more importantly has big pit-zips. Would Versalite with pit-zips be more breathable than BD Alpine and be more modular for the rain/snow/wind?

Are those of you using Alpha Direct wearing it as a base layer (directly on the skin) or as a mid-layer? For the latter option, would mesh base layer still be a superior option under Alpha Direct or would such two super air permeable layers (mesh base and alpha direct) stacked on top of each other be redundant?

Thank you in advance!

[Steve H]

I have been blown away by how useful & versatile my Macpac Nitro has been (kinda need to size up thought).

Does anyone have any experience with the new Patagonia R1 Air?

And what happened to the Patagonia Thermal Weight hoody?

[Weekend Gear Guide]

Stephen: Do you have any CFM, MVTR, warmth-to-weight clo/oz/yd2 and CLO comparison between your Polartec Alpha Direct 60gsm and Polartec Alpha Direct 60gsm x 2 against your new Mountain Hardwear AirMesh Hoody that you can share with us here?

Also, I just released an Active Insulation Jacket Series Part 1 video, which may have some info that you and our fellow BPL members may find interesting:

Active Insulation Jacket Series – Part 1 – Technical Introduction

The Active Insulation Jacket integrated 2-3 layer composition presented in my video is more traditional, like the Rab Alpha Flux Jacket and the generally highly regarded Arc’teryx Proton FL Hoody, as oppose to your advise to just use Polartec Alpha Direct by itself. While I still do find comfortable in my activities using traditional Active Insulation Jackets like I mentioned in my video, I do see advantages with just using Polartec Alpha Direct like the Rab Alpha Flash Jacket., and perhaps will try it out.

Cheers!

 

[Metamorphosis]

Thank you for raising these. That information would certainly be helpful.

Related to that note, I am struggling to understand the benefits gained by opting for Alpha Direct (other than weight saving). For my particular use during winter months in the Whites, a slightest breeze would make it totally useless as a mid-layer (unless I put on a wind layer over it). But, putting a wind layer, combined  with its high clo value, would make heat management a challenge. What happens when high exertion overwhelms the system and sweat build up? Wouldn’t a wicking material (hydrophilic) serve better in that case than hydrophobic material that Alpha Direct is made of? This is where I am having the most difficulty understanding its applicability. Isn’t the main focus during winter high exertion activity to let sweat pass through our layers so they can finally evaporate on the outermost layer away from the skin? How exactly would having a hydrophobic layer under a wind shirt going to facilitate sweat transfer from the base layer underneath?

[Stephen Seeber]

Hi Meta:

I use Alpha as one component in a moisture management system that is oriented to removing moisture vapor, not moving liquid sweat from layer to layer.  My experience with hydrophilic layers is that they get wet and remain wet.  As far as I am concerned, looking at the latest wicking layer is not an answer for my activities.  Sounds like it is not a solution for  you either.    My next three articles will deal with this issue.    The research, lab testing and writing are going slower than I expected, as often happens with complex topics.  However, if you follow the series, I hope to answer all of your questions.

[Weekend Gear Guide]

Hi Metamorphosis,

You’re welcome and thanks for watching!

Regarding what you mentioned:

Related to that note, I am struggling to understand the benefits gained by opting for Alpha Direct (other than weight saving). For my particular use during winter months in the Whites, a slightest breeze would make it totally useless as a mid-layer (unless I put on a wind layer over it). But, putting a wind layer, combined  with its high clo value, would make heat management a challenge.

I would assume the warmth-to-weight clo/oz/yd2 for Polartec Alpha Direct would be very similar to the known 0.38 clo/oz/yd2 of regular Polartec Alpha, as shown in the Active Insulation comparison chart of this section of my video:

Active Insulation Comparison Chart

As you can see, Polartec Alpha is not as warm as some of the Fiberfill based active insulation shown in my chart.

So if you are considering purchasing the Norrona Lyngen Alpha90 or even something warmer like the Rab Alpha Flash Jacket I mentioned previously, perhaps one of these may work with your BD Alpine Start, but if you are worried about excess moisture buildup, then maybe switch to a higher CFM windshirt like a bike jersey  with about 200 CFM/ft2, as Stephen mentioned above (you’ll need to ask Stephen what bike jersey he is using) or some dedicated windproof, >10K HH water proof Gore Infinium running jacket with breathable underpanels/back panels that help dump excess moisture vapor buildup like the Arc’teryx Trino SL Hoody.

 

[SIMULACRA]

Reminds me of Polartec Hardface. North Face used it in their Summit series L2 hoodies many years back. Tried one out for winter use. Had a very porous grid fleece inner and hard/smooth face outer. Great moisture management during high exertion. Made for easily slipping on/over outer shells.

[Author]

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