The Search for a Fleece Replacement – A Close Look at Active Insulation and the role of MVTR

[Stephen Seeber]

Companion forum thread to: The Search for a Fleece Replacement – A Close Look at Active Insulation and the role of MVTR

What is MVTR’s role in active insulation garments?

[chad b]

Great write up!  Very thorough and useful for the coming change of season. Also, I noticed you mentioned after market pitzips on your shell.  Did you add these yourself or have a company/tailor do it? Any resources you could share?

Thanks

[Indrit S]

Excellent article Stephen! Thank you very much.

[Link .]

Chad, Stephen talks about the pit zips he had added in THIS thread

[Stephen Seeber]

Hi Chad:  I have had pit zips added by two local companies, both of whom did very good jobs.  Gear Re-store USA in Thornton, CO,  https://gearrestore.com/  and click on the US store or Boulder Mountain Repair in Boulder, CO https://bouldermtnrepair.com/

 

[chad b]

Thanks Stephen! Thats actually in my neck of the woods!  I’ll check it out! I look forward to more great content!

[Brett Peugh]

Thank you Stephen,

I know you suggest something with a high MVTR, pit zips, 2 way front zipper, and adjustable sleeve cuffs.  Would the MVTR really matter if you have a jacket with the other three things like the, https://antigravitygear.com/shop/product-category/ultralight-backpacking-rain-jacket-with-pit-zips/ that can really open up and if so how and why?  Thank you.

[Stephen Seeber]

If so, I would have worn my Versalite forever and the Versalite likely has far higher MVTR than the garment you link to.  A large part of what works for you depends on your  MET level and the environmental conditions you hike in.  Also, how frequently you are willing to change layers during your activity.   So my solutions may not be your solutions.   The higher the MVTR and the greater the ventilation possibilities, the more I can adapt to a set of conditions without adding or removing layers.  I can maintain protection from rain, cold and wind over a much greater range of conditions if I can readily dump moisture while preventing wind and rain from entering my outer layer.  As this becomes inadequate to keep up with moisture production, I can open the ventilation I need.

That jacket that you link to, as stated in the description, is not breathable. It is designed as a rain jacket.   It will be like wearing a plastic bag.  You will rely entirely on having enough wind moving through the jacket ventilation openings to remove moisture. This could be a problem in still air at hiking speeds.   In the attempt to remove moisture  by opening the zips, you will compromise your ability to be protected from wind, cold and rain.  I am guessing that backpacking in such a jacket will result in moist layers and discomfort.  When the weather turns cold or windy, you will be constantly fiddling with zippers to try to dump moisture while trying to maintain comfort in adverse conditions.

[Ethan A.]

Stephen, what’s the MVTR of the Montbell Versalite? I’ve heard such good things about it and had great experience with the earlier Montbell Peak Shell, which, while not super breathable, was a big step up from the Patagonia rain shell I used before it and impressively durable.

Also, if you don’t mind my asking, how much did they charge to put the pit zips in your jacket, including labor + materials, and what type of zipper did you install?

I’ve hesitated with Shakedry due to concerns about the durability. Also, it would be nice to have some color options other than black.

[Brett Peugh]

Thank you then.  I guess it would be nice if they made these more MVTR jackets in an XXL but I have not seen one yet that you source.  If you do know of one, please let me know.  6’5″, 220#s with a long torso puts me out of most things.  Thank you

[Stephen Seeber]

Ethan: Versalite is around 2300 on my scale.  Montbell lists the results on the Japanese test scale that most use.  It is 43000 for Versalite and 80000 for the Peak Dry Shell (Shakedry).  Versalite is in a different league than the Montbell Shakedry.  I have paid from $100 to $120 for pit zip installation.  YKK waterproof zipper was installed.  As you can see, a lot of trade offs go into this decision.

[Steve H]

I am going to try and pair the EE Visp with the Macpro Nitro and will let you know how the Visp runs.  Appreciate all your knowledge and advice.  Steve

[Brett Peugh]

Hello Stephen,

Would the difference of about 500 Shakedry and Houdini using the Alpha Flash be noticeable?  Thank you.

[Stephen Seeber]

I think so.  Let me put it this way:  During winter use, I seldom get condensation on the interior of my Shakedry jacket.  When I used a Versalite or Houdini, which both have similar MVTR, I often would get condensation on the interior of my wind layer.  The Versalite  pit zips improved performance in marginal conditions, compared to the Houdini.

[Brett Peugh]

Thank you.  And I believe you said the next rain jackets after the ShakeDry would be the Electrospuns.  And certain models of those that stand out?  Thank you for all the testing you do, it looks like it is really changing people’s perspectives and viewpoints.

[Edward Barton]

Stephen, Great article! I’m interested in the discrepancy between your findings and the preference for higher CFM active layering strategies among some experts in the BPL community – I can think of Max Neale, Ryan Jordan, and Dave Chenault as examples. I wonder if you agree that there is a discrepancy here, and if so if you have any thoughts about why there hasn’t been more of a consensus movement toward lower cfm/higher MVTR wind layers. One thing that occurs to me – Richard Nisley mentioned that the pumping effect would significantly increase MVTR beyond static measurements, during a previous discussion, here. I imagine the pumping effect may disproportionately increase MVTR in garments with greater air permeability – ie water vapor would be more easily ‘pumped’ out, all else being equal. Could this lend a benefit to higher CFM outer layers not captured in your testing? Or do you think the pumping effect is minimal enough that it wouldn’t alter your results?

[Stephen Seeber]

Hi Edward:

Thanks for reading!

If you have not, I suggest you read my prior article, here:  https://backpackinglight.com/air-permeability-vs-mvtr/  In this article I specifically study the impact of air permeability and MVTR on moisture elimination.  The garment that produced, by far, the greatest moisture removal had no air permeability and the highest MVTR in a WBP garment on the market.  The statistical analysis demonstrated that air permeability had only a minor role  to play in moisture removal.  I elaborate further on this behavior in the current article.  I cannot speak to the opinions of others.  However, in this and the former article, I have attempted to described the forces involved along with physical testing that supports my conclusions.  My findings drive my clothing choices and my field experiences provide a means of verification.   As I have mentioned in a number of articles, where I hike, higher air permeability tends to just make me cold when a cold wind is blowing, which is much of the year.  Without the wind blowing and wearing a moderate CFM jacket, I have to be more active in removing my wind layer to avoid excessive moisture accumulation in my base layer.  Concerning pumping:  There are two ways pumping may occur:  1) simple air circulation within the garment due to movement of garments as you walk and 2) intake of exterior air with a similar volume of interior air displacement to the environment, again, due to movement.  In the case of type 1, no moisture vapor will be removed.  In the case of type 2, moisture vapor will be removed.  This type of  vapor removal has nothing to do with MVTR, which is inherent to the garment fabrics.  Due to the very low air pressures produced at hiking speeds, as is discussed in the article, it is not clear to me that air permeability can support much pumping due to air movement through the garment fabric.  However, when you are hiking during adverse conditions such as cold and wind, you probably don’t want cold air penetrating your garments.  In this case, you would prefer high MVTR to remove moisture and a tightly sealed garment to keep out the low temperatures.

[Stephen Seeber]

Hi Bret:

I don’t have a standout garment for the electrospuns.  Previously, they were available with pit zips.  I just took a look and did not see any with pit zips.  Perhaps you can find one with pit zips. All of the examples I have tested have produced similar MVTR performance.  The garments I tested tended to be the lightest I could find at the moment since higher denier face fabrics will tend to reduce MVTR.  So, look for a very large size in the lightest weight jacket you can find.  This might be of interest: https://www.backcountry.com/patagonia-ascensionist-jacket-mens?s=a  MVTR is 2400.  Not bad. Price is right.    I will be testing an EE Visp shortly.  They seem to have your size.  Might be a good solution for you.  Stay turned for test results.

[Brett Peugh]

If I may ask, what was the similar produced MVTR of the electrospun jackets? Yeah, I didn’t see any with pitzips.  I have a bit of credit with OR so I ordered the Ascentshell Motive to try out and see how it works.  Thank you.

[Stephen Seeber]

MVTR ranged from 2800 to 3000 for Neoshell, Ascentshell and Futurelite.

[Brett Peugh]

That seems to be better in the than every rain jacket but the Montbell but then again I have not seen a comprehensive list of them.

[Brett Peugh]

I do believe you said the 2019 Marmot Precip had a good MTVR

[Brett Peugh]

You say the color of the double  alpha you got was maroon.  Is that the same as the raspberry color for Far Pointe?  Thank you.

[Stephen Seeber]

It is raspberry

[Brett Peugh]

Thank you for all the help Stephen.  Is it possible to get a big list of all of the rain and wind jackets you have tested with MVTR and air permeability?  Thank you!

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