Wicking, yay, nay, or "it's relative" to the importance?

[Anonymous]

The question of wicking and it’s importance seems to be a mildly controversial area here, though not often discussed or debated in depth or detail.

I’m curious who thinks what and why?

I lean to think that wicking has some importance, but is overly hyped by marketing sources.  More specifically, i think certain garments, like underwear, gain from wicking well.

My other hypothesis is that wicking won’t make much of a difference if you’re sweating so much as to completely wet out the clothes, but makes more of a difference if you’re more so spot or localized sweating (small of the back, armpits, etc).  In the latter case, spreading the moisture over a larger surface area seems to speed up the drying time.  But in the former case of full saturation, i’m not sure if wicking fabric will dry noticeably faster than non wicking?

If there are any studies or research into these relative areas, please share.

And besides the obvious rain shell garments, are there areas or times when non wicking is a plus?

[Lester Moore]

Wicking and proper layers for conditions is very relative to what kind of person you are. I sweat very little unless I’m pushing hard uphill, so any kind of base layer and insulating layer seems to work fine for me, as long as it’s warm enough for the conditions. In contrast, I have one friend in particular who sweats so much, he has to change base layers and liner gloves multiple times each day while doing day climbs – and he’s tried all kinds of different clothing options. His wife sweats even less than I do and she can wear nearly anything she wants without sweating much.

Clothing seems to be one of those things that you just need to dial in through experience, so you know exactly what to pack, what to wear when, and what to leave at home for every type of outing and type of weather conditions.

[Anonymous]

Agreed that it’s relative to and dependent on the individual to some extent, but i’m also interested in universals.  Like, most people can benefit from greater air permeability in rain gear systems, and it seems to be one of the most consistently bemoaned and wanting to improve areas for a lot of folks.

I’ve found the very different, polarized opinions in this area, interesting.  I’ve seen some people say that wicking doesn’t matter at all, and is just market hype, and i’ve seen some people say that it’s very important, especially for baselayers.  Perhaps some of that is based on those individual differences like you mentioned, but sometimes i wonder if perhaps there is more going on.

I don’t have firm beliefs on it either way.  My experience leans to support wicking as generally being good.  I’ve worn a regular, tightly woven supplex, non wicking, nylon shirt (World Wide Sportsman brand) during a hot and humid hike, and it felt more clammy and uncomfortable versus wearing a bit more breathable and much better wicking shirt also made out of nylon (Kuhl Wunderer).  It’s hard to say how much of that was due to air permeability differences and how much was due to wicking though.

I run warm in general, but i wouldn’t say that i sweat excessively/unusually.

[Clue M]

If I want  sweat to run down my torso past the waistline and towards my feet, I want non wicking, otherwise I see wicking as a benefit.

[Jerry Adams]

“it’s importance seems to be a mildly controversial area here” – ha, ha, ha,…

wicking – marketing spin

I wear nylon shirt.  It gets wet.  Water will evaporate out of my clothing system regardless of anything

More important for the base layer to not absorb a lot of water so it’ll dry quickly

But, I leave the door open slightly.  My gaiters and long pants are nylon and absorb water.  My socks are Merino.  For some reason, if it’s raining, the water doesn’t go from gaiters/pants to the socks.  The socks are anti-wicking.  Water just runs down gaiters/pants to the ground.

So, if that works, maybe you can get other applications of combination of hydrophobic and hyrdophilic.  Like Paramo jackets.

 

[Jon Fong / Flat Cat Gear]

IMO – wicking is a critical factor for certain circumstances.  I found this article to provide a lot of insights: How The Navy SEALs Prepare For Extreme Cold Weather Survival, And How You Can Too.

Now, not everyone hikes in the arctic, and I think that cotton=death is overstated as well.  For me, I find wicked materials to work well and are really not that expensive or inconvenient to use and maintain.  HYOH

 

[Jerry Adams]

That’s a great article

I thought the point was more that synthetic insulation will dry from body heat, even if it’s fully saturated with water and you’re in arctic conditions

Not so much about wicking

[Anonymous]

Perhaps i should have defined what i meant by wicking (i was trying to be less pedantic ;)  )?  I meant when a fabric has moisture touch it, and the moisture gets pulled in and spread out over a larger surface area (non scientific definition).

Old synthetic fabrics/garments didn’t wick at all in this manner.  Some still don’t, especially among nylon garments and fabrics.  With these, if you drop water onto the surface, it beads up and just sits there until it evaporates, falls off, or slowly makes it ways in between the fibers in a localized way. Interestingly, while nylon and polyester have a significant difference between moisture regain properties, some of the common forms have a very similar surface energy–which means unless altered they bead up water similarly.

Many polyester sportswear type garments on the other hand are now very well wicking.

Wicking in synthetics can be accomplished in several different ways; altering the fiber shape to have greater surface area so instead of a fiber that looks like a . at the end, you have one look more like an * or x, you can put a temporary finish/coating on the surface of the fiber–some material that is hydrophillic or hygroscopic, you can combine two layers of different sized fibers, or you can blend it with a minority blend of hydrophillic fibers.

I haven’t found any quilt or bag to have a well wicking shell fabric.  I don’t think the internal insulation, even if synthetic, particularly wicks in this manner either–it just doesn’t absorb as much moisture into it’s actual material as the natural ones and so tends to dry faster.

[Roger Caffin]

that wicking has some importance, but is overly hyped by marketing sources.

When all you have is spin, then all you can do is spin. Facts and science don’t count.

But otherwise, I think I agree with your (Justin’s) comments.

Cheers

 

[Ralph Burgess]

Perhaps i should have defined what i meant by wicking (i was trying to be less pedantic ;)  )?  I meant when a fabric has moisture touch it, and the moisture gets pulled in and spread out over a larger surface area (non scientific definition).

Capillary action.

https://en.wikipedia.org/wiki/Capillary_action

In the extreme counterexample, if you wear a  completely waterproof garment, your sweat stays inside the material next to your skin, and cannot exaporate, so you get hot and clammy but don’t cool down.

In a “wicking” material, capillary action draws water from the sweaty body to the external surface, where evaporation proceeds rapidly.

That’s the concept, and as you’re already discussing it’s plausible the the structure of the fabric could have a significant effect, but I have no idea if there’s evidence of a substantial difference among porous materials or if it’s just marketing spin.

 

[Jon Fong / Flat Cat Gear]

Wicking helps to pull moisture away from your body. When water is pulled into the wick, the water spreads out and the surface area increases substantially. Body heat and the increase surface area allow the water to evaporate quicker.
In high humidity, this faster evaporation rate gives the sensation of being cooler. When you wear a silk shirt in the topics, it feels cool to the skin as silk is a great wicking material. If you sweat out a silk shirt (saturate) the capillarys become full and the wicking drops off: you will feel hot again.
In the arctic condition where the SEAL was soaked in water, the only source of heat is the body. The materials that they chose were wicking and insulating. The goal is to be warm and to have a transport mechanism to get the water away from the body. I suspect that they are really using a series of wicks: base layer, mid layer and outer layer. Wicking pulls water away from the body and increases the water’s surface area. Body heat and increase surface area causes the water to vaporize faster. In the case of this article, the mid and outer layers provide some insulation to keep the person warm. The water vapor migrates through the base, mid and outer layers due to the diffusion gradient.

 

My 2 cents

[Franco Darioli]

The body produces sweat to cool itself down.

If your garment wicks really well than your body has to keep sweating to cool itself down.

When that happens you need to drink more.

That means extra weight.

And that is why when really hot I prefer a Merino T to something that sorts of keeps me dry.

But this is not a scientific opinion, just the way I see it.

BTW, I also have noted that those that drink a lot (say 2-3 times the amount I do) also sweat a lot. Therefore they carry more water repeating the cycle.

Again nothing to back this up except my own observation.

[Ralph Burgess]

The body produces sweat to cool itself down.
If your garment wicks really well than your body has to keep sweating to cool itself down.
When that happens you need to drink more.
That means extra weight.
And that is why when really hot I prefer a Merino T to something that sorts of keeps me dry.

Franco, your reasoning doesn’t hold because sweating only cools you down when the water evaporates.   It is the extremely large latent heat of vaporization that makes this such an effective mechanism for thermoregulation.  For example, it takes around 7 times as much energy to convert boiling water from liquid to vapor as it does to raise the temperature of liquid water from room temperature to boiling point.  When liquid water on the surface of your body or clothing evaporates, this massive amount of energy is sucked out of your body.   That’s why sweating works, and why “cold and wet” is an extremely dangerous condition for a hiker.

https://en.wikipedia.org/wiki/Latent_heat

 

[Matt Dirksen]

“If there are any studies or research into these relative areas, please share.”

Here’s a 2013 commercial/military study which I found interesting and relivant to this topic. While the study was focusing on one particular wicking fabric, it did test it in conjunction with a few of the popular wpb’s. The study was primarily looking into what happens to vapor transport when the arrangement of the hydrophilic and hydrophobic layers is reversed.

http://www.hindawi.com/journals/jtex/2013/216293/

It’s a little wordy, so here is their conclusion:

“Permeation cell measurements demonstrated that the rate of liquid wicking was conveniently reflected in a measurable cooling effect on the fabric surface due to water evaporation. Results from vapor transport testing with wetting/nonwetting fabrics show that there are very large differences in drying time that can impact the rate at which the evaporating sweat from the body is transported through the fabric to the environment. Orienting a hydrophobic/hydrophilic fabric with the hydrophobic side towards the human skin surface and the hydrophilic surface towards a laminated reactive polymer membrane laminate is more efficient than the reverse orientation at picking up liquid from the skin surface and moving it to the polymer layer where it is available for hydration and chemical reaction.”

 

 

 

[James holden]

Ask yourself 2 questions …

• if it isnt wicking away and eventually evaporating, where is the moisture going?
• If the moisture is still in the baselayers next to the skin, what happens when it gets cold?

theres a reason why high performance athletes use wicking base layers generally

for the output of walking around in more mild conditions, almost anything will work

if one doesnt believe in “wicking” then one should simply not use any polartec powerdry …. And call cap4 hocus pocus

the entire premisis of that fabric and garment is wicking …

;)

[Ralph Burgess]

eric, I have asked myself… and I’m not sure what you’re getting at.

If the moisture is still in the baselayers next to the skin, what happens when it gets cold?

It doesn’t get cold if it’s trapped next to the skin – this is the principle of a vapor barrier, right?   It just stays at skin temperature and feels clammy.

But we’re not talking about a vapor barrier here.   So…. yeah, I don’t really understand what they are claiming for Powerdry in terms of keeping you warm.  The website says

Polartec® Power Dry® pulls moisture directly from the skin and transfers it to the outer surface to quickly dissipate. This continuous evaporation process helps to keep you cool (as your body heat increases) and warm (when temperatures begin to drop).

…..the “warm” part of which makes no sense to me in a static situation.

The way I view wicking in Cap4 in cold temperatures is that even in winter you sweat when when active, and you want this to wick away quickly and dry off while you are still moving and generating body heat, so that when you stop moving your clothing is not soaking wet.  Is that what they mean?   If so, they have expressed it very badly – it sounds like a claim that evaporation per se is keeping you warm.   What they really mean is that the chilling effect from evaporation occurs quickly when you want it to while you are still generating body heat, so that your clothing is almost dry and warm when you stop.

[Jerry Adams]

If the water isn’t wicking away and evaporating, where does it go?

Eventually, all the water evaporates and it takes the same amount of heat regardless of where it is

Wicking, to the degree it works, will make the skin feel drier, but it’s mostly aesthetic.

power dry or cap 4 are still good base layers, even if the wicking claim is mostly marketing

Minimize sweating by not wearing too much

 

[James holden]

If the moisture is next to your skin and its cold …. Youll get cold … Period

the purpose of wicking is to move the moisture away from the skin towards the outer part of the layer

thats the entire reason of powerdry … Its made of bi component fabric for that reason

merino is actually quite wicking even more so than the various synth materials as its hydrophillic … The problem is that once ot wicks moisture towards the outside it doesnt dry fast enough at high output activities

like i said folks can get away with anything walking …

its when folks are pushing the human limits or the limits of conditions, or both … That these things really start to matter

;)

 

[Ralph Burgess]

If the moisture is next to your skin and its cold …. Youll get cold … Period

eric, again – that’s somewhere between wrong and misleading, depending on context.

It is evaporation that makes you cold, by sucking out the latent heat required to turn the water from liquid to gas.   The key is how quickly the liquid water evaporates – it evaporates more slowly when it’s next to your skin, and more rapidly when it’s on the external surface and exposed to low ambient vapor pressure.

In the extreme case of “zero wicking”, i.e. a perfect vapor barrier layer, you trap the moisture next to your skin, humidity rises quickly to 100% inside the layer, after which there is no evaporation at all and therefore no cooling effect.

With normal clothing (no vapor barrier), for a given quantity of liquid water, if more of it remains closer to your skin, the evaporation will be slower, and the cooling effect will be less, but it will last longer, since the clothing will take longer to dry out.

So, as I said – I think the motivation for wicking in Powerdry cold-weather baselayers is to mover the liquid away from your body while you are moving, to evaporate faster and increase the cooling effect while you want to be cooled, rather than let the sweat build up and cool you more slowly but over a longer period, which is a problem if you stop moving and stop generating body heat.

[James holden]

Ralph

when yr soaked in the constant freezing rain there is no evaporation (or wicking when its saturated, as ive pointed out in previous threads) if you dont move… Yet folks get very cold, go hypothermic and die

same with water immersion in cold lake

like i said anyone who doesnt believe wicking works should simply trash ther cap4 and r1s

Theres a lot of theories on BPL …

ill post up some links when im  back home and on a real puter in a few days …. Climbing right now

;)

 

 

[Ralph Burgess]

 

when yr soaked in the constant freezing rain there is no evaporation (or wicking when its saturated, as ive pointed out in previous threads) if you dont move… Yet folks get very cold, go hypothermic and die

same with water immersion in cold lake

You’re jumping sideways to scenarios that have no relevance to the question of the  wicking properties of a material.    Vast quantities of freezing water applied FROM the outside by freezing rain, or immersion in a cold lake, where everything is completely soaked through, are not “moisture next to the skin”.    Obviously in these unrelated scenarios I agree that evaporation is not the dominant cooling effect.

Wicking is relevant to persipration, from which the dominant cooling effect is evaporation.   Only with the smaller quantities of water from perspiration is it a realistic question to even ask “what difference does it make whether the moisture remains next to the skin or is wicked to the surface?”

[Jon Fong / Flat Cat Gear]

From the interweb:

The energy requirement of an average man is 2,500 Calories per day, and one Calorie is 4184J. Therefore he emits about 10.5MJ/day or about 120W.  An average woman requires 2,000 Calories per day, so she emits about 97W

The Latent heat of vaporization (energy required to vaporize water) 2264.76kJ/kg

To vaporize 100 grams of water would require 226.4 kJ or 54 calories.

You will feel cold depending on the rate of vaporization.  If you vaporize 100 grams in 10 minutes, you will lose 377 Watts.

When you are in a hot and humid climate, we want to lose heat as quickly as possible.  Wicking allows the water to spread out and increase the surface area.  Convection cooling (wind) should be more effective due to the larger surface area as well.  The evaporative cooling will be driven by the internal body temperature as well as the differential humidity of the air/boundary layer near the body (100% relative humidity wind is not going to feel that cool).

In cold climates, the same effect is occurring.  However, the difference is that you wear insulation to trap in heat that the body produces.  You can drive the water out by generating more internal heat (increase your activity).  The evaporation rate will be dependent on the surrounding humidity as well as the diffusion through base, mid & outer layers.  This is why doing activities in the winter takes a lot of practice (and why hypothermia is such a problem).  High excursion, strip off layers for improved venting/expelling moisture.  Cooling down, wrap up to retain heat.  My guess is that the combo of base, mid and outer layers is designed to control the rate of vaporization: too fast and you will feel cold, too warm and you will sweat.  The right long term balance, is that you will feel moist but be warm.  Hiking in the rain/cold requires a lot of futzing.

If you are out in the rain and soaked to the bone, you are kind of hosed.  The key would be to find shelter (stop excessive water from entering your system) and use the SEAL technique.  Exerting more energy will increase the burn rate in your body driving off more water, however; there are limits as to how long that will work.  I would guess that if you carried a boatload of high calorie food that you could make this last a long hike.  It’s all about energy balance.  That and at the end of the day, you will still need to find a shelter to dry off (or at least feel moist but warm).

I also agree with Roger: there are a hell of a lot of Marketing claims out there.  And they are called Marketing claims because there is not technical data to support it.  That being said, I am a proponent of wicking materials because I find that they work for me (hot and cold).  I like merino wool and I like some of the cheap “activity” tee shirts.  My 2 cents.

[jared h]

adding to the debate between Eric & Ralph:

“If the moisture is next to your skin and its cold …. Youll get cold … Period

eric, again – that’s somewhere between wrong and misleading, depending on context.”

Eric is 100% right with his statement. water is a more efficient conductor of temperature than air because it has a higher density. if the water against your skin is colder than you, it will cool you more than the same temperature of air against your skin (the inverse is also true for warmer). and wind enhances the effect, because it will strip heat from not only your body (convection, but cool the water against your skin. if you doubt the science, try standing outside in 55 F weather with no jacket and see how long you last. now go jump in the ocean off the coast of Seattle (55 F water).

“In the extreme case of “zero wicking”, i.e. a perfect vapor barrier layer, you trap the moisture next to your skin, humidity rises quickly to 100% inside the layer, after which there is no evaporation at all and therefore no cooling effect.”

Ralph…not quite. evaporation is not the only way to cool your body. when the sweat cools (and it will in cold weather), it will cool your body through convection (cooler air/water moving over your skin) and you will be cooled through conduction (touching the layers that are constantly cooled by the ambient air even as your body warms them). if the humidity rises to 100%, it will either move through your layers/shell membranes, or exhaust out the holes in your jacket. and really, this point does not matter because internal humidity has little to do with wicking (moving moisture from your skin to outer layers) or evaporation (this has to do with external humidity). high internal humidity actually speeds the process of moving vapor through your layers, so not sure what you are trying to say.

in the case of the ‘perfect vapor barrier,’ what you mean is a ‘perfect liquid barrier,’ because as you sweat and add moisture to a 100% humid environment (assuming you could maintain it), it will immediately condense into liquid. the only instance i can think of this is with a wetsuit. not that the barrier is perfect, but the neoprene traps a thin layer of water/sweat against your skin, keeping that waste heat energy against your skin, and providing a denser fabric barrier between the colder ambient water and the moisture against your skin. but even then, wetsuits are only good down to 50ish F.

So, as I said – I think the motivation for wicking in Powerdry cold-weather baselayers is to mover the liquid away from your body while you are moving, to evaporate faster and increase the cooling effect while you want to be cooled

partially right. in cold weather, you do not want moisture against your skin because of the conduction and convection heat loss effect of water against your skin. when you are moving, you want water to evaporate, but the need for it to cool you is limited; you really just want to remove water from your layers because it is dangerous to have wet layers, even when you are moving. among the dangers are: reduced insulation from wet layers, lower body temperature as your activity slows, and frostbite even as your internal body temperature is high enough to sweat.

the cooling effect of sweat, to cover both ends of the temperature question. sweat cools your body in two ways:

1. <span style=”line-height: 1.8;”>the water carries heat energy (and toxins, and other things) from inside your body to the surface. this is how internal soft tissue (e.g. muscles) dump waste heat from the calories they use as energy.</span>
2. on the surface, evaporating water takes heat from the water that remains on your body, lowering the total heat energy on your skin. you do not get this effect when you wipe the water off. also, if the outside temperature or wind is cooler than your body, it can cool the sweat against your skin, cooling it. of course this reduces the evaporation effect, but still works to cool you (no idea which has a stronger cooling effect, i just know what to wear depending on the conditions and activity).

synthetics wick liquid from your skin, wool absorbs water vapor before it condenses on the skin (assuming close proximity to the skin and it is not already saturated). people use them together because they work in complimentary ways. either way, you want to move the moisture away from your skin because spreading it out accelerates evaporation and/or allows it to be cooled by cooler air, and spreads out that cooling effect around your body.

[Matt Dirksen]

” This is why doing activities in the winter takes a lot of practice (and why hypothermia is such a problem).”

+1  to that.

I would also add that conductive heat loss is a BIG deal in the winter,. In my recollection, the body looses heat about 25 times faster when subjected to water at the same temperature as air. A person who has saturated their base/mid layers in sweat will rapidly loose heat simply through conduction, especially if their expensive wpb jacket has wetted out and is no longer able to “breathe”. Even if the jacket is totally windproof, a person will soon feel the “coldness” of the wind if every layer is wet in-between them and the outside air (and they are stationary.)

In my days of wintertime white water kayaking, I remember being told the horror stories of drysuit failures. A small tear or a zipper fail could result in significant loss of dexterity in minutes, regardless of the multiple wicking layers or fleece underneath.

[Ralph Burgess]

jared

now go jump in the ocean off the coast of Seattle (55 F water).

If you jump in a pool of cold water, of course you get cold mighty fast by conduction.   This tells us nothing at all about the process of perspiration, by which we exude a small amount of water initially at the same temperature as our body.    Now, I agree, once the layer of sweat gets cold, then the process by which it then sucks the heat from our body is conduction/convection between skin and liquid.   But how does the sweat get cold?   The answer is, almost entirely by evaporation.

When you say that the wind cools a wet surface more rapidly than a dry surface in wind – yes it does, by making the water evaporate faster.

If you think that the presence of a water layer also affects conductive/convective heat loss significantly, the burden is not just to show that there is significant absolute conductive/convective heat loss water>air.   Of course there is, just as there is for dry skin  skin>air. The question is whether there a significant difference in conductive/convective loss between

(a) skin > air

(b) skin > water > air

I’m not aware of any evidence that this is the case, and “I get cold when I jump in the sea” really does not illuminate the issue.

https://en.wikipedia.org/wiki/Perspiration#Mechanism

Sweating causes a decrease in core temperature through evaporative cooling at the skin surface.

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