Why is my base layer soaked?

[Jerry Adams]

yeah, good info

or, unzip the front.  That removes a lot of effective insulation if you’re starting to sweat.  That’s easier than removing layers.

that’s pretty extreme to dig the snow down to the ground, add sticks, sleep on sleeping bag without tent

[Bruce Tolley]

@ Stephen, The article uses the terms moisture and wicking in the same sentence multiple times. So it appears by this context that moisture is limited to liquid perspiration.

But water vapor from perspiration also moves through the base layer and other layers.

Or do you include water vapor in your definition of moisture?

[Stephen Seeber]

Hi Bruce:

Thank you for reading.

Of course water vapor moves through a wicking layer, or it can, until it encounters temperatures below dew point, saturated capillaries, or a low MVTR layer.  Wicking, by definition, concerns movement of liquid water, not vapor through a fabric.  MVTR measures vapor transmission.  My test method for wicking does not specifically track vapor movement.  Vapor transmission in my wick/dry test does occur and can be more or less measured for fabrics that exhibit very poor wicking. The quantity tends to be small.  However, the surface area of the sponge that supplies water in the test is 8.4 sq. inches.  The surface area of the garment under test is about 189 sq. inches.  In view of the minimal surface area that can support water vapor loss, the preponderance of water that is lost to the environment during the test, occurs due to adequate capillary capacity and rapid transverse wicking that spreads water across the surface of the test garment.  As described in the article, the greater the surface area that is wet, the higher the amount of evaporation that can occur.

The importance of water vapor transfer in eliminating moisture in an ensemble or even a single layer,  has been a recurring theme since I started posting on BPL.  The question you need to be asking is what is a better way to turn sweat into vapor? Wicking moisture away from the skin into a fabric where it is less likely to turn into vapor and be eliminated or layering to encourage water vapor to be produced on the skin and then be eliminated through the layers?   Hopefully, in the two articles I have posted, and the ones that follow, the basis for answering that question will be fully explored and documented.

 

[Ian H]

Hi Stephen, thanks for another thought-provoking article. At high temperatures like 30+C I’m sure the transverse wicking (transferring sweat across the fabric) is real, and more relevant than purely through-fabric wicking. My personal experience is with lawn-mowing, a traditional Aussie summer activity, which is generally done as fast as possible to get it over with and cease annoying the neighbours (and is done on hot/bushfire risk days when you’d be nuts to go walking for ‘fun’). Doing it shirtless the sweat from underarms trickles down, with a shirt on there is a broader wet zone (and less visual offence to the neighbours). I’ve given up the shirtless look (before the neighbours sign a petition) but it feels more comfy in a shirt, particularly OR Echo or Capilene, or Icebreaker 150 Merino, than bare skin. Good old cotton gets really soggy and generally unpleasant fairly quickly, to the point where I’d usually remove the cotton shirt as soon as the beer was in hand.

I suspect the spread of moisture across a broader area of the shirt allows better evaporation/ cooling  (especially in full sun at 30-40C) than bare torso skin. Bare legs sweat less (above boots, I value my toes) so less of an issue. Lightweight nylon hat soaks up a lot of sweat before eventually dripping into eyes.

The problem of warm rain is when you need a waterproof outer layer, but are still exerting enough to sweat. I’m currently in the Lakes District of England, 14-18C by day, pretty continuous light drizzle with intermittent heavy rain bursts and colder winds. Pit zips and repeated opening/closing the front zip to balance internal vs external moisture.

Your results on airspeed to assist evaporation confirm the impression that wind helps, even if there’s high humidity. In these days of electric ski boots and gloves, has anyone tried a computer fan to increase airflow? I wonder whether a pit fan would be higher airflow than a pit zip, or a back of neck fan to suck air from under the pack area, allowing the front zip to stay closed.

Cold weather sailors and oil rig workers wear non-breathable waterproof fabrics, often with cowls/vents at the back for some airflow. Compared to the cost of Gore-Tex etc, could a fan-forced garment made of cheaper material be more comfortable/ safer? My car can adjust the airflow to maintain temperature, and my phone adjusts the screen brightness, are we at the stage when Siri could work out that I’m climbing a 1 in 1 gradient and increase the airflow before I notice I’m getting sweaty?

[Jon Fong / Flat Cat Gear]

blö – my class did a study on this.  I am sure that there are better options (as well as a better name).

 

 

[Stephen Seeber]

Hi Ian:  Here in the US we just finished up Don’t Cut Your Grass In May.  Unfortunately, I could not honor that because I did not want to cut 2 foot tall grass on June 1.

Funny thing about bare skin:  when you sweat enough, gravity causes rivers of sweat to flow down the path of least resistance.  It actually wastes a lot of sweat, which simply rolls away without evaporating, soaking into your pants or somewhere else of no use.  A shirt can help eliminate that waste but, once the shirt is saturated, may still lead to wasted sweat.

 

[Jon Fong / Flat Cat Gear]

Summertime in the Sierras, I often bring 1 cotton t-shirt, high altitude, low humidity, warm temeratures, it works out fine.  Wicks sweat and evaporates quickly.

[Bruce Tolley]

“wasted sweat…”  That’s a good one.

Perhaps evolution intended for us to sit in the shade and not be out in the sun carrying a back pack.

[Author]

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