Cool clothing for hot, humid weather–Under Armour Iso-Chill shirts, etc

Interesting… I am not sure I have seen a shirt of this style made of nylon before. I like the durability and the non (less) stinky properties of Nylon. I normally think of nylon as hotter but I guess that is from tighter weave nylon like nylon supplex. It also doesn't seem as nice feeling against the skin as polyester, but I do really like Ex Officio Give N Go boxer briefs (and they seem really popular around here too) which are nylon so maybe they are on to something.

I am interested to see peoples comments because I hike (and run) a lot in hot humid weather and I have thus far settled on open weave meshy polyester tops (like Cap 2, Mountain Hardwear Wicked, OR Echo) but am always interested in something better.

Not UA but got a Columbia omnidry because I liked the color and needed a wicky exercise shirt, …worked it out on a backpack and it was ok, nothing special. Seems to work better jogging without a pack. Honestly for backpacking where the day is guaranteed hot, I'd just wear a cotton blend and keep a light 3-layer system in the pack for night/rain.

What about that columbia omnicool or the mountain hardwear cool q zero (same thing) with those little circle things that are supposed to keep you cool. Sounds like total BS to me, but I'm still curious about it. For the dry hot weather we get around here cotton works great. Never really been in hot and humid.

@justin – I meant omnicool or -freeze. Again didn't notice it much backpacking vs cap 1 (it's all polyester and it all wicks to some extent).., a bit more cooling sensation during jogging or walking without a pack than other wicky layers. All this at a sunny 75°F or so. May need to dayhike or bike at about 10-20°F higher to really test it. Piles up pretty fast though.

"Never really been in hot and humid."

Lets just say that a Patagonia Capaline 2 T Shirt or Mountain Hardwear Wicked T gets soaked from sweat on day 1 and wont dry the entire trip. Same with thin wool socks, Trail-runners, etc.

My first trip out west the biggest shock I had was that my clothes I hiked in were dry 20 minutes after I stopped.

Nothing dries here in the southeast, you just get used to hiking in damp clothes.

I have never hiked in the PNW or Alaska (hoping to change that next year) but I would expect them to be similar.

Hi Bradford, i may be partially incorrect, but i think the feel of polyester vs nylon has a lot to do with a combo of weave, size of the fibers (the smaller the fibers, no matter what kind of material, the softer it will feel), and texture/shape of fibers. Otherwise, there is no inherent superiority of polyester vs nylon here, just that nylon has gotten into a rut being mostly made into supplex and ripstop type nylons. It's less commonly used for knits.

I wanted to like the Ex Officio boxers, but the ones i bought and the ones i tested in the store recently do not wick well at all. If you drop water on the surface of the inside, the water just beads up and stays beaded up. They could very easily modify this fabric to be more wicking. Brushing the inside of the fabric for example, would make it more wicking and softer to the feel.

I really like the OR Echo series, but i question how truly permanent the polygiene treatment is–if you read between the lines in their literature, they mention a hundred washes which is impressively durable but not necessarily permanent. I don't care about looks much at all in a social sense, and i would wear pretty much anything if it was pragmatic to do so, but i do care about stink because in my mind it signifies a build up of potentially pathogenic organisms. Not as big a deal with shirts, but more so underwear or anything near one's crotch.

Some honorable mentions for stuff that i have found which does feel more comfortable in hot, humid weather and which has decent to good stink control: Already mentioned the OR Echo line; a thin, breathable camp type shirt made out of slight majority of nylon to tencel, a thin, breathable dress shirt made out of 65% polyester and 35% linen, and the Kuhl Wanderer all wicking nylon button up shirt which isn't as breathable as the previously mentioned or the UA Iso-Chill, but is good for buggier conditions and wicks decently (not excellently) and is textured so feels good against the skin.

Btw, one of the things that UA claims for the ISO-Chill is that it feels cooler to the touch. Surprisingly, there does seem to be some truth to this. It's not a dramatic difference, like say between feeling wood and some kind of metal, but it's enough to notice. So apparently it is conducting heat away more efficiently than typical fabrics. I suspect they are using flatter/wider/thinner yarns that are both trapping less air and providing wider surface area of material that is more conductive than say rounder, thicker yarns?

I have highish hopes for the UA shirt, but i'm always looking for other good stuff in this area.

Justin and HK Newman,

The Columbia stuff looks interesting, but i have two misgivings about it. One, i've read some reviews which say that they build up stink fast and hold it well, and two i question the long term durability of the material. Once those rings start degrading and disappearing, it's just a wicking polyester shirt.

Same with the stuff that adds xylitol to it–that stuff will wash out over time.

"Otherwise, there is no inherent superiority of polyester vs nylon here, just that nylon has gotten into a rut being mostly made into supplex and ripstop type nylons. It's less commonly used for knits."

It may be important to note that nylon is a more expensive material than polyester, which is probably one of reasons why polyester is such an ubiquitous synthetic fiber. A lot of polyester comes from recycled PET/#1 plastic and so is very cheap and plentiful.

Being more hydrophobic than nylon, it will dry a bit faster given the weave/thickness and all other factors between a nylon and polyester shirt are the same. However, one could argue that some true absorbency might be a good thing for the evaporative cooling effect?

One of the new fabrics on the market that is designed to be more actively cooling is something called "Cool Core". They apparently achieve this by layering a couple or few different yarns together in the same weave. One yarn is a typical, highly wicking synthetic and another is a tubular, hollow yarn with little holes that pull moisture into it and circulates it providing a longer evaporative cooling effect, while the other wicking yarn provides the more quickly cooling evaporative heat loss effect and both pull moisture off the skin.

In a sense, it's somewhat mimicking the way that linen and hemp work naturally (being absorbent, hollow straws of yarn basically), except that it's all synthetic and they are adding a more typically wicking yarn too.

I posit that combining a majority of flatter/wider/thinner wicking nylon yarn, with some linen or hemp would also work very well in this area. Anything from a 60% to 70% nylon ratio to 40% to 30% linen or hemp blend should work excellently for a more active cooling effect while providing good moisture management comfort.

Hint, hint Michael from Sierra Designs ;)

You are probably right Justin as most (if not all) of the nylon garments I have are really tight weave supplex type nylon. I am not sure I have ever seen a lose knit nylon.

I like the Ex Officio boxers because they don’t stink terribly after a week in the backcountry. I guess wool would do the same thing, but I have been really happy with the Ex Officios.

It’s funny you mention the Echo shirts because I have looked at them on and off and was just looking into them again the other night. I think I am going to pick up a longsleeve one based on your and other reviews. I am just trying to figure if I want the Medium or the Large. I don’t like a real tight fit and it says trim fit, which would lead me to a large, but the shirt on the model seems pretty loose.

I had started to assume that polyester was cheaper than nylon in its raw form because I see most of the supplex nylon hiking shirts are now some sort of poly-nylon blend.

I have an long sleeve Echo shirt with zipper. By far the coolest most breathable garment I have, very welcome for the hot and very humid summers here. Compared to Patagonia or Arcteryx Medium I would say the OR Echo Medium I have is more loose.

I don't do all that much hot/humid, but I do some

When it's hot, it's usually sunny, and there are often bugs – a supplex like fabric is good – long shirt and pants – a bit baggy for better air flow – light color to absorb less sun light

Chemical sun and bug repellents aren't that effective and may be unhealthful or unpleasant. Long pants and shirt also protect against scratches

The percentage of time is small, that it's hot but not sunny, buggy, and I'm not walking through brush some. So it doesn't justify having a seperate outfit.

I do 6 days wearing the same shirt. A bit smelly but not too bad. I could wash it in just water. I don't sweat that much.

If it's hot, the shirt will get damp from sweat and then start cooling from evaporation. Doesn't matter that it isn't very breathable. If you want bug and sun protection, it can't be breathable. Wearing a wet shirt is sort of unpleasant, but you get used to it. The supplex dries off quickly.

I carry spare shorts, underwear. If I fell into mud, for example, I could wear the spares, wash the pants, underwear in water and let them dry. Or if I shredded the pants I could wear the shorts for modesty.

I live in the Baltimore MD area (nicknamed the "Devils arm pit" back before air conditioning was common). We have 95% humidity and 95 degree heat a lot in the summer. I've tried cotton, poly, and nylon t shirts. The poly ones were noticeably less clammy / sticky / not breathable feeling than the nylon. The cotton ones absorb enough moisture from the air to become damp to the touch (even when hung over a line in a breeze to dry). Wool is way to warm in 90 degree heat, and looses its ability to absorb moisture in humid climates.

Loose, light colored, open weave poly shirts are about as comfortable as you can get for hot humid climates. The loose fit is important. It causes the shirt to billow and pump air when you move so it doesn't stick to you as much.

"The poly ones were noticeably less clammy / sticky / not breathable feeling than the nylon."

Regarding the "breathable" part, that's all based on weave when it comes to synthetics. Most nylon fabrics are both woven and semi to very tightly woven, which makes them much less breathable.

A nylon knit will be just as breathable as a polyester knit if similar sized interstices between the fibers. By nature, knits tend to be more breathable than woven fabrics.

The UA Iso-chill shirt is one of the few nylon knit shirts i have even seen. There are some other ones out there, but they seem to be kind of rare. Even the difference of porosity between the Kuhl Wanderer all nylon, but woven shirt, and the UA is quite noticeable. I would hazard to guess that the UA shirt is at the very least twice as porous as the Kuhl one, and the Kuhl one is a bit more breathable than some of the other woven nylon shirts i've had or breath tested.

Btw, i agree with you that loose fitting, airy clothes help. The fabric and clothing of choice back in the day for Euro and American explorers in the tropics was typically thin, loosely woven, light colored and somewhat baggy/loose fitting all linen, long pant and long shirt clothes. It was the only thing back then that was tolerable for these folks who were not used to such hot and humid conditions. (As a side note, linen does have some nice cooling properties. I was testing this the other day, by dropping some drops of water onto various wicking fabrics, gently blowing on them, and feeling the coolness of the fabric right after. Linen and the UA shirt felt the coolest. The wicking polyester shirt did not feel as cool. But part of comfort in these conditions is the fabric feeling dry faster–which the polyester will do well if it's thin enough.)

"If it's hot, the shirt will get damp from sweat and then start cooling from evaporation. Doesn't matter that it isn't very breathable. If you want bug and sun protection, it can't be breathable. Wearing a wet shirt is sort of unpleasant, but you get used to it. The supplex dries off quickly."

Sure, the supplex will dry quickly if it's thin because it's synthetic and the interstices are small and don't hold as much water, but the same lack of porosity also inhibits/slows down evaporation of sweat from the skin, which is not good for hot, humid conditions.

I have a hard time wearing supplex when it's both hot and humid, especially since most of it doesn't wick well (they are starting to change that, but the cheap stuff like Bass Pro Shops affiliated brands still doesn't wick).

Bugs: When i was in Fairbanks Alaska a couple of early summers ago, during some truly horrendous mozzie conditions and unusual (for them) heat, i wore a ls linen shirt that was more tightly woven than the typical very breathable linen. As long as i was moving some, the shirt provided adequate protection. Granted, if i was perfectly still for awhile, i would get bit some.

Point being, you don't quite need typical supplex type weave to protect against most bug bites. Though if you were in a malaria prone area, you'd want that extra, worry free protection. But in areas where disease is not much of concern, i'll take the extra porosity and greater comfort with an occasional bug bite, any day over sweating my booty off in supplex. If i was in a disease prone area and had to spend a lot of time outside, i would wear a more breathable, pants and ls shirt and then bug netting over same. In Alaska, we didn't do much bushwacking at all, and i wore rather baggy bug netting over bare legs/shorts. It was baggy enough to keep the bugs from biting, especially when moving.