Maximizing cool clothing strategy for hot, dry, sunny desert?

[shane c]

<div>Other than utilizing shade, like an umbrella…</div>
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<div>Job #1, I assume, is minimizing heat gain with light colored clothing to maximize reflecting radiant heat from sun and from heated up desert terrain around you.</div>
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<div>Is there any clothing fabric claiming to be more effective in reflecting radiant heat than just it being white?</div>
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<div>Job #2, I’m assuming, is maximizing the cooling effectiveness of evaporative cooling from sweat.</div>
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<div>Is bare skin the most efficient, if you ignore for the moment that it is not very reflective for direct radiant heat gain and UV is an issue, too?</div>
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<div>If so, would not a tight fitting, more reflective, high wicking fabric, like thin tights, be the closest thing to bare skin efficiency in evaporation cooling?</div>
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<div>And, with some claiming to be exceptional at wicking and even wider dispersing of the sweat, like CoolCore and Arctic Cool, might that not be the best then when in a more reflective light color?</div>
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<div>Or, am I missing something here, to where lightweight baggy loose vented clothing is even better for cooling than the above? If so, how and why?</div>
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<div>Baggier clothing seems to me to restrict air flow and evaporation and some of it that does get wet and cooler from evaporation does not stay touching the skin flopping around, but is there something good, going on here, too, to have evaporation slowed and/or that trapped air not blown away so quick as with either bare skin or tights? Is there anything good about having that buffer of air between skin and looser clothing that’s desirable to aid cooling?</div>
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<div>I’m ignoring the garments’ other requirements and attributes here, just looking for now, at what’s coolest clothing strategy for hiking in the hot, dry, sunny desert.</div>
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<div>Appreciate any thoughts.</div>

[Jerry Adams]

arab people wear white robes – cover all skin, loose/baggy for more air flow inside

most solar energy is in visible wavelengths, so white is good.

reflective material like space blanket would be better, because it also reflects IR, but it’s not breathable.  This is only useful if it’s greater than body temperature 99 F.  And if it’s only a little hotter it wouldn’t make much difference.  110 F, 120 F, 130 F – that’s when there’d be significant radiative heat.

If you’re shirt was wet, and cooled from evaporation, air flow would carry that coolth to your body even if it didn’t touch

[Nick Gatel]

You might want to define “hot” temperatures. 90F, 100F, 110F, 120F?

Desert climates vary depending upon the time of year. In the heat of summer, those of us who venture out to hike usually rest in shade during the hottest part of the day, unless there is lots of water available.

Where I live, high temps are often 115F or higher in summer. Not many people can or should do strenuous activities in this kind of heat unless one is aclimated. Do you want to stay cool, or do you want to stay cool and have SPF protection? Few people are going to hike in 110F plus temps. It is very rare to find temps above 120F, despite what you might read.

If you provide more detailed information I can tell you what has worked for me in the 40 years I have lived, worked, and hiked in deserts.

[Matthew / BPL]

Good thread topic.

The coolest setup I have found for the blazing Arizona sun is a loose fitting polyester knit top with a hood and long sleeves (Patagonia Tropic Comfort Hoody) in light grey. I wear it without a hat unless I am hiking right into low angle sun. I haven’t found anything else that comes close.

I have used Sunday Afternoons Sun Sleeves and found them to have a noticeable cooling effect if the humidity is low and wind is present. In any conditions other than that I find loose sleeves to be much cooler.

[Matthew / BPL]

Nick raises a good issue about the heat. My comments above are tested into the mid 90s in full sun. I don’t hike in temps past ~95° except by accident.

[shane c]

I’d define hot as above 100F in bright sun very low humidity desert. Lack of any breeze and late afternoon heated up terrain makes it worse quicker.

I’d like to be dressed right so I’d both minimize heat gain and sweat less cause I did so more efficiently cooling me when I did, so I could go farther carrying less water reserves.

Sweat that ends up falling off me or cooling clothing away from skin contact is wasteful, no?

[Anonymous]

The ideal combination for desert hiking is a cotton spandex knit, thin, breathable, somewhat form fitting, dark colored in the torso and light on the arms shirt.  Cotton spandex blends hold onto moisture more than most other combos. That’s good in the desert, prolongs the cooling affect.

Over that, a very light colored, sort of short and smaller poncho like top made out of thin, even more breathable, and also absorbent material (just fold over a rectangular piece of fabric in half, and curve cut a hole for the head). The more stiff the better, so a linen or predominant ramie fabric would be best.  You could also increase stiffness and keeping it off your body by thin, halved bamboo inserts or the like in strategic places–sort of like a lightweight frame.

What you’re doing with this combo is prolonging your moisture cooling effect, while keeping the heat of the sun off you as much as you can sans an umbrella.  Some older desert cultures did this with thick, flowing, breathable robes–that could work too if you do it right, but the above combo will likely be cooler.

It also provides extra UV protection (except to your lower arms), while still maintaining breathability.  Single layer fabrics that blocks UV well, are usually rather tightly woven and not particularly breathable.  Generally dark colors absorb/block UV more efficiently, hence why the under shirt is dark except in the exposed parts of the arms.

Granted, with a get up like this, you might look a little strange, but you DID ask about ultimate efficiency of staying cool in such a climate. I don’t care about looks–especially not on the trail. I care most about practicality and efficiency, and with a penchant for adaptable, changeable systems.

[shane c]

Mathew, Like that you found hood works, and without hat. Your valuable sweat is less apt to be lost in hat or drip away unused elsewhere.

I was looking at a white balaclava of thin CoolCore, popular with fishermen. (I see Israeli soldiers utilizing CoolCore balaclava, too, though not in white.) Full head/neck reflective white coverage and sweat retention where it’ll do most good evaporating in close skin contact seems worth exploring.

Was thinking, too, that in very dry desert we lose a lot of moisture with every exhalation and balaclava might trap some of that moisture in material when exhaling, which could both add to evaporative cooling right there around mouth/nose and also help moisturize and cool next inhalation.

[Anonymous]

I find Cool Core to be warm feeling unless it’s fairly soaked. In super low humidity desert conditions, moisture evaporates so fast, that Cool Core doesn’t get particularly wet enough to work well, except maybe on your back with a pack on.

Cool Core is most efficient for moderate humidity (like 30 to 65%) and hot temps.  Those are the somewhat rare nice days for around these parts.  Usually it’s on the upper end or worse.  Cool Core doesn’t particularly work well in very high humidity conditions either–I find it overly warm feeling then as well.

What makes “cotton kill” in cold, or cool and wet conditions, are the same properties that make it cooling and nice in low humidity, hot temps. But provided it’s breathable enough and not too thick.

[Edward John M]

I’ve lived and walked in Alice Springs Australia

When it is really hot, walking can and does kill people unless there is a lot of water available.

The advice to hole up and rest during the hottest part of the day is correct and spot on.

Portable shade in the form of a white and/or reflective tarp works well

Multiple layers of very light loosely woven natural fibres work best in extreme heat but polyester mesh is a close second place in my experience

Parasols are surprisingly effective but the big reflective golf umbrellas would be even better if there was no wind and you didn’t mind the weight.

Desert walking can be very, very hard work as sometimes there is a need to carry huge volumes of water, water needs limited most of my walks to 2 or 3 days because of the need to carry 6 to 8 litres of water for each day

Also you need to allow for very cold nights, temperatures in Central Australia can have differentials of 35C degrees or more and most deserts exhibit this sort of temperature swing

Very hot during the day and plummeting close to freezing during the nights

 

[shane c]

Justin,

Cotton spandex blends hold onto moisture more than most other combos. That’s good in the desert, prolongs the cooling affect.

I get this, but have often wondered about the logic…

The cooling effect from x amount of sweat evaporated is the same whether it takes 1 minute or 5, yes? It’d just be greater cooling when in shorter time frame.

So, if non cotton fabric evaporated x amount of sweat in that shorter minute, I’m cooler faster and then my need for sweating more declines sooner, yes?

Of course, if not low humidity, I don’t want sweat to be wasted dripping off me and would prefer then that it got trapped in cotton, but in low humidity with full coverage that’s not an issue.

If I get maximum evaporative cooling all the time as fast as I can I don’t see cotton’s slower evaporation rate as a benefit, at most it’d be a wash in how much cooling x amount of sweat delivers.

[Anonymous]

Dunno about it in a scientific, research way.  Just basing it on my own experience with going to different climates and trying different fabrics, blends, and styles.

My usual wear when I go to the desert and very low humidity, hot conditions, are breathable, 55% linen 45% cotton, light colored, button up, long sleeve shirts.  I’ve found this more comfortable than wearing polyester, nylon, and the like (whether knit or woven).

When I responded earlier, I spoke more hypothetically, but based on a combo blend of experience and holistic logic.  I suggest experimenting and figuring out what works best for you. I’ve yet to try that particular combination in desert or desert like conditions, but next time I’m there, will try it out.

 

[shane c]

Justin,

I find Cool Core to be warm feeling unless it’s fairly soaked. In super low humidity desert conditions, moisture evaporates so fast, that Cool Core doesn’t get particularly wet enough to work well, except maybe on your back with a pack on.

Are you saying that it helps keep your back cooler, sweating less?

Does it wick it out a bit into borderline areas where air can then be gotten to it?

[shane c]

Edward,

Desert walking can be very, very hard work as sometimes there is a need to carry huge volumes of water, water needs limited most of my walks to 2 or 3 days because of the need to carry 6 to 8 litres of water for each day

Also you need to allow for very cold nights, temperatures in Central Australia can have differentials of 35C degrees or more and most deserts exhibit this sort of temperature swing

Very hot during the day and plummeting close to freezing during the nights.

This brings up an interesting opportunity, lots of water, cold at night.

I see these guys using night time radiant cooling in deserts to make ice when it’s still well above freezing.

Not that you need to make ice, but what if you really chill the heck out of your water every night and then wear it the next day in a bladder in your pack right up against your normally sweaty back? Anything that keeps you cooler longer means less sweating and water usage.

[Anonymous]

When I’ve been in the desert and desert like conditions, the only time I really noticed sweat was on my back where the backpack touches.

Cool Core is designed to cool best when nearly completely wetted out. Otherwise, I find the combination of fine polyester fibers, mixed with hollow polyester fibers, to be warm feeling on the skin when dry.

But yeah, in moderate humidity, where you wet out the fabric from sweat and it’s low enough humidity that it will actually evaporate somewhat, it works great.  Particularly nice was a bike ride with a house mate on a hot, south eastern day with rare moderate humidity.  I had soaked and rung out the Cool Core shirt and similar fabric tube on my head and neck, and all that wind was quite nice and cooling.  It worked exceptionally well when it was still fairly wet.

But nothing stays wet in super dry desert conditions, especially not a wicking polyester based shirt.

[Anonymous]

“I see these guys using night time radiant cooling in deserts to make ice when it’s still well above freezing.”

Not sure what others are doing or not, but the same inverted conical cardboard-aluminium foil Solar cooker I made, which works very well as a solar cooker, also makes an excellent radiative cooler at night under open sky.

[shane c]

Justin, yes, same basic set up, aluminum foil solar cooker.

I hear you, too, about the insulation qualities of CoolCore when not sweaty wet can work against you.

Supposedly, it’s helpful spreading out and moving sweat some, wondering if it’d at least help on perennially sweaty back. Love to find something that’d decrease sweat and/or put it to better use cooling instead of just pooling up there.

[Anonymous]

Kool Beans on the Solar cooker Shane.

Funny enough, I contacted the company that designed and sells CoolCore fabric and garments and offered them some suggestion to improve their product.  Suggested that if they switched out the polyester for nylon, and maybe added a little tencel or especially linen blended in (like 25% to 30%)–they would have a truly awesome product.

Nylon is both a bit cooler feeling on the skin, and noticeably less stinky (also lighter and stronger). One of the issues for me about CoolCore besides it’s warm feeling when dry, is that, in least in this humid climate, it builds up odor fast and holds on to it.  Sure, you could do a Polygiene treatment which would help, but a combo of majority nylon with some tencel or linen would do just as well and more permanently.  Polygiene isn’t truly permanent.  Quite long lasting if you baby it, but it’s technically rated for a 100 washes.

Buildup up of oil can also eventually overwhelm a Polygiene treatment I’ve noticed also. Less problem of that with a nylon-tencel or linen blend.

But the idea to use hollow synthetic fibers with small holes in them, in combo with more spread wicking fibers, is a great one.  A little modification and it would be much better.

“Supposedly, it’s helpful spreading out and moving sweat some, wondering if it’d at least help on perennially sweaty back. Love to find something that’d decrease sweat and/or put it to better use cooling instead of just pooling up there.”

It wouldn’t be too hard to take that same knit cotton spandex blend shirt, cut out part of the back and sew a quicker drying and more wicking fabric to it (that and there are packs out there that don’t rest on the back and thus cause this issue to begin with). I prefer thin, knit, wicking nylon over polyester though.

[shane c]

Interesting, you contacting CoolCore and all, hope they listen.

We may see more variations from others licensed to fabricate clothing with CoolCore, too. I’ve noticed the blends run from 100% polyester all the way down to 85%, usually a spandex or variation for the remainder. Some are pre-treating with an anti-stink. Also, noticed some are very fine and thin, like silk, and others much thicker with bigger spaces or pores. The outdoor and fishing outfitters will be one group to watch, Cabella’s done a little, but GILLZ is supposed to have an extensive new line of CoolCore garments in the spring. Somebody will likely nail it, or has already, we just haven’t tripped over it, yet.

[Anonymous]

Somewhat surprisingly, someone did get back to me (eventually) and sort of agreed, and said that they have other things in the works and to keep checking the site.  They thought I might be a materials researcher.  “You sound like a…”

Nope, just a fabric/materials nerd–mostly self and BPL “trained”.  It’s funny, before I came to BPL, I didn’t care or think too much about equipment, tech, and the like, and just hiked in or used whatever. I use to do hikes up Mt. Washington and in the Whites in cotton (NOOOOO………!!!).

Sometimes I wonder if I wasn’t better off before my left brain hemisphere became so hyper involved in over analyzing and weighing everything.  There’s a certain equanimity in just being and not thinking–like the average animal.  Just one of the various reasons why I tend to take extended vacations from this place–for my own sanity–for BPL is like a black hole of materialist hyper focus–the chant drones ever louder–gear, gear, gear, gear… must have more, must have newer, shinier, better, never satisfied with what I got…gear, gear, gear, gear.

Not surprisingly, it’s when I recently got away from daily meditation (because of traveling) and general focusing on attunement is when I let myself get sucked back in.

(wonder if this qualifies as unconscious rabble rousing?)

 

[shane c]

I hear you, it’s all about balance or cycle, for me I throw myself into figuring out getting what I need and then as focused, drop it all to go and do. Repeat.

Been to top of Mt Washington, twice in one day, but no hiking up or down then. Via car up, flew off east face in hang glider, landed at Wildcat parking lot, then rushed back up to fly off west face landing in cog railway parking lot. Locals said we’d lucked out, wind never calm enough to fly but maybe once or twice a year. That was BM & BC in the 70’s, ‘before marriage’ and ‘before children’. I’m an ol’frt.

[Edward John M]

It’s counter intuitive but sometimes you need a heavy windproof exterior shell over the LW open weave stuff

If  a HOT WIND IS BLOWING and they do often here, you need to keep that hot wind from getting to your skin surface

So often we think of wind as having a cooling effect, in a hot dry desert this is not always the case.

[shane c]

Edward, yes, too true that, have to first minimize heat gain wherever it comes from best you can.

Besides hot wind, I’m also reminded how miserably hot the terrain can get in late afternoon after soaking up the sun all day. The long wave radiant heat emitting off dark rock faces or piles is formidable, like walking up to a fire. And, then there is walking on it, too.

 

[Anonymous]

Agree there is a balance Shane. Not easy to achieve though.

Edward, that makes sense if the hot wind is significantly warmer than the body temp.  I would liken it between a regular toaster oven and one of those newish so called “air fryer” cookers that super circulates the air and cooks the food faster (and more evenly) than a regular toaster oven.

So in a very hot desert wind you cook faster and more evenly?  Haha… :(

I don’t think I’ve experienced such extreme conditions yet, at least not in that sense.  To me though, nothing is worse than 100 degrees (38* C) and 80% or higher humidity, and your sweat evaporates so inefficiently and slowly… arrgh, a true environmental hell. The only saving grace is that these same places usually have plenty of water.

[shane c]

To me though, nothing is worse than 100 degrees (38* C) and 80% or higher humidity, and your sweat evaporates so inefficiently and slowly… arrgh, a true environmental hell. The only saving grace is that these same places usually have plenty of water.

100% agree, hate high humidity/heat. Sometimes so bad, unlimited fluids is not even enough, found out hard way. Spent 14 hours in Gulf of Mexico becalmed heading to Aransas Pass in temps/humidity so high I stayed skin wrinkled soaked from sweat, sun up to sunset, drank tons of ice water, gatorade, V8’s, etc., constantly drowning in fluids, but was still dehydrated, never could pee, near end cramping up, cloudy thinking, no urine all day, not once, till hours after dark when I finally caught a breeze and limped in and then it was only a very dark trickle. Had paramedic son rig me up with IV’s and solutions to carry on board after that. Also, got me an enema bag. No fan of high heat/humidity here.

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