wicking fabrics < promoting dehydration?

[Bushman5]

We all know the old adage cotton kills in the wilderness, by absorbing sweat, becoming clammy and wet and rapidly chilling the body.

but what about modern fabrics, such as the hydrophobic wicking fabrics that wick moisture off your skin and push it into the next layer of clothing? could these fabrics actually be promoting water loss (dehydration) to some degree?

as an example, when i used to wear snug Coolmax cycling jerseys in hot weather, I often found myself reaching for the drinking tube a lot more, and refilling the water pack a lot more compared to when i would cycle in a cotton tshirt in the same conditions.

Can such water loss be measured? can such fabrics even be compared or tested somehow?

do wicking fabrics promote dehydration?

discuss

 

[Calebklyne]

i dont think its the fabric sucking water out of your skin as much as it is the fact that a lot of moisture wicking fabrics are closer to the skin and therefore dont allow your skin to breath as well and make you heat up faster

 

[Josh K]

By wicking the sweat up to be evaporated I would say it actually reduces the sweat you produce.

 

[Munky88]

It wicks away sweat. Sweat that's supposed to be there to cool you off by evaporating. But it never gets a chance to evaporate because it gets wicked away, so you sweat more.

 

[ohen cepel]

Excellent question, I have never thought about it!

Good point to ponder.

 

[Josh K]

It wicks away sweat. Sweat that's supposed to be there to cool you off by evaporating. But it never gets a chance to evaporate because it gets wicked away, so you sweat more.

Or it spreads (via wicking) the sweat out over the fabric increasing the rate of evaporation.

 

[pitdog]

Natural fibres such as cotton soak the sweat up just as fast (maybe faster) but just hold onto the sweat longer thus remaining damp and allowing you to chill more. They would have no effect on your dehydration.....at least that's my understanding !!!!

 

[kgd]

It wicks away sweat. Sweat that's supposed to be there to cool you off by evaporating. But it never gets a chance to evaporate because it gets wicked away, so you sweat more.

The evaporative cooling works regardless. Whether the actual cooling takes place in the centre of the polyester wicking material or on the surface of your skin, there is still a net draw of heat to facilitate heat of vaporization. Since the wicking material, polyester, has very poor heat capacity, the energy is pretty much coming from your skin. So I tend to disagree with Munky on this one. If you cool down you will sweat less. If you have sweat soaked cotton, that water on your shirt will retain heat and act like a heat sink in itself, so your body will continue to sweat in an effort to cool down.

Wicking fabrics are good for heat management and will not contribute to higher dehydration rates.

 

[dextersp1]

We all know the old adage cotton kills in the wilderness, by absorbing sweat, becoming clammy and wet and rapidly chilling the body.

More important than sweat is rain.

but what about modern fabrics, such as the hydrophobic wicking fabrics that wick moisture off your skin and push it into the next layer of clothing? could these fabrics actually be promoting water loss (dehydration) to some degree?

You are putting the cart before the cart on this one. Modern fabrics do not promote sweat.
The key item is that if you are sweating - regardless of synthetics or cotton. That is you body telling you that you are overheating. That is what is causing the dehydration. You should slow down and/or lighten up on the clothing.

Modern synthetics wicking action helps to keep you dry and cool.

Modern fabrics do not lose their thermal properties when wet while cotton does.

 

[Bushman5]

so how does one explain (and yes there are many variables) why i'm always super thirsty after a slog with wicking clothes than the same slog (same conditions) with cotton clothes?

 

[Pritch]

so how does one explain (and yes there are many variables) why i'm always super thirsty after a slog with wicking clothes than the same slog (same conditions) with cotton clothes?

It could be that your synthetic clothes don't breathe as well, causing heat retention and consequent sweat.

 

[Josh K]

so how does one explain (and yes there are many variables) why i'm always super thirsty after a slog with wicking clothes than the same slog (same conditions) with cotton clothes?

You could have been more dehydrated. The humidity could have been elevated. The sun could have been in a different position. The wind could have switched directions and speed.

 

[Bushman5]

they breath great, if i hike in subzero temps you can see a mound of frost on t he OUTSIDE of the outer garment, while the inner is dry. Thats what you want in a breathable garment, moisture pushed away from you.

and yes, i'm aware the thousands of variables (temps, humidity, etc etc etc etc etc etc etc etc) but i still notice that i'm more thirsty when hiking with synthetics than my cotton. I know when i'm thirsty. I know my own body.

 

[Skimo]

No offense, but it sounds like a head case.

Try wool next and see if it's similar to cotton or synthetics.

Come to think of it, it could be conditioning (also head case) the feeling of being more dry makes you feel thirsty.

 

[dougo83]

and yes, i'm aware the thousands of variables (temps, humidity, etc etc etc etc etc etc etc etc) but i still notice that i'm more thirsty when hiking with synthetics than my cotton. I know when i'm thirsty. I know my own body.

Two things:

1. Thirst does not necessarily have anything to do with dehydration. Yes, there is a slight correlation between the two, but one can be thirsty and perfectly hydrated.

2. Don't be so fast to discount those "thousands of variables" as they are the answer. Humidity, sun position, etc can contribute to your core temperature and prompt you to consume more liquid. Also, the different materials breathe differently,s o you may not be getting the air flow that you would with cotton.

 

[beef]

Hi Bushman
I don't think there would be any difference. Whether evaporation occurs on one side of a piece of fabric or the other, I think the cooling effect would be the same.

Regardless, if there were a difference, it would be infinitesimal. You run/walk while wearing your insulating clothing, if I read your previous thread correctly
?
I personally sweat profusely even in low temps while walking, wearing nothing more than a thin shirt and pants. I'd suggest that your chest rig (which I think is kind of neat) and insulating layers would contribute more to increased sweating and therefore dehydration than cotton vs manmade fabrics.

Just reread my response and it sounds kind of snotty. Not meant to come across that way.

 

[Bushman5]

no no man, its not snotty at all, lol.....

i do know i sweat MORE with a backpack on vs my micro chest rig.
I do know that depending on what i eat many hours before i start hiking, that food either makes me feel like a nuclear reactor, heatwise, or nothing at all.
I would be very keen on studying this in a more scientific manner, should anyone be interested in funding such a study.....lol

 

[Bushman5]

No offense, but it sounds like a head case.

Try wool next and see if it's similar to cotton or synthetics.

Come to think of it, it could be conditioning (also head case) the feeling of being more dry makes you feel thirsty.

this sounds very plausible, mind over matter..........

 

[James 61]

I am going to school to become a nurse and as part of my studies I have been learning a lot about Human anatomy and physiology. As we all know sweating how our bodies shed excessive heat. Skin is an amazing organ and is water proof and highly resistant to all kinds of chemicals, bacteria etc&#8230; Because of the water proof nature of skin and the way in which sweat glands work it is not possible for the fabric to pull water out of your body.

As to why you are drinking more water when you are wearing wicking fabric there are a number of possibilities. Most of these have been mentioned but I have a thought of my own. It is possible that the improved wicking properties is keeping you cooler which is allowing you to exert yourself more and this is increasing your water consumption.

 

[Jason B.]

I wear UA almost everyday in the winter and when I need it in the summer, I have never experienced the problem you seem to be having. Personally I don't feel it does much in hot weather besides keeping my skin and outer shirt dry. In the cold its ability to keep me warmer and keep moisture off my skin is where I find the most benefits.