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A cool guide to heat absorption between different colored T-shirts (i.redd.it)
submitted 10 months ago by partybot to c/coolguides
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[–] [email protected] 68 points 10 months ago (1 children)

"The amount of heat gained by a Bedouin exposed to the hot desert is the same whether he wears a black or a white robe. The additional heat absorbed by the black robe was lost before it reached the skin."

Bedouin robes, the scientists noted, are worn loose. Inside, the cooling happens by convection - either through a bellows action, as the robes flow in the wind, or by a chimney sort of effect, as air rises between robe and skin.

Thus it was conclusively demonstrated that, at least for Bedouin robes, black is as cool as any other colour.

https://www.theguardian.com/education/2006/aug/15/research.highereducation

[–] [email protected] 16 points 10 months ago (1 children)

But t shirts don't work like Bedouin robes.

[–] [email protected] 5 points 10 months ago

Only if you don't know how to sandwalk, Outworlder.

[–] FunderPants 35 points 10 months ago (3 children)

So white and yellow for staying cool, every other color heats up.

[–] [email protected] 16 points 10 months ago (1 children)

Tradeoff is dark colors absorb more UV so it provides better protection from the sun

[–] [email protected] 39 points 10 months ago* (last edited 10 months ago) (3 children)

Umm…

~~Reflection is just as effective as absorption. As long as the UV isn’t passing through the fabric into you, you are fine.~~

Well butter my biscuit, I might be wrong. There are other of factors to take into account, but it makes sense that, the portion of light that does make it through a light fabric will keep on reflecting inside the garment until it is absorbed or escapes back out. Like a photography light box.

[–] [email protected] 8 points 10 months ago* (last edited 10 months ago)

Skincancer.org is my source for darker colors being better protection

https://www.skincancer.org/blog/dress-to-protect-5-things-that-affect-how-well-your-clothes-block-uv-rays/

I don't have the highest degree of confidence in it but it makes sense to me that absorption matters more than reflection because a lot of the reflected UV will be going through the shirt and onto your skin

That's why materials like linen aren't as good for UV protection. They're light weaves and let a lot of light through, still

[–] [email protected] 3 points 10 months ago (1 children)

Look at the sun through a white shirt, then black. Which is brighter?

[–] [email protected] 1 points 10 months ago

The white would be as it would absorb (then converted to heat) less light and would reflect it instead.

Thebottom half is highlighting the absorption by showing radiance (giving off it's own/stored energy), not reflection.

[–] [email protected] 3 points 10 months ago

Gotta get that UV colored tshirt :-)

FYI there are UV absorbant tshirts, crazily practic for kids.

[–] [email protected] 14 points 10 months ago

Red looks surprisingly effective as well.

[–] [email protected] 5 points 10 months ago (2 children)

Its a bit misleading. Black clothes will absorb the heat from the sun and your body and then the clothes will cool via convection. So the wind blowing through the clothes takes the heat away. White will reflect the heat from the sun away and your body back towards you.

Im sure theres some debate and probably way more to it but i have always felt more comfortable in the heat than other people and i wear darker clothes the majority of the time. If that anecdote bares any weight.

[–] BCsven 2 points 10 months ago (1 children)

Google says : colors do not absorb different amounts of heat, only heat from light.

[–] [email protected] 3 points 10 months ago (1 children)

Heat from light isn't heat?

[–] BCsven 1 points 10 months ago

Light is energy, if a medium absorbs the light it converts to heat. if it reflects it the potential heat goes away with it

[–] FunderPants 1 points 10 months ago

Are you telling me a human body is different from a manikan torso?

Seriously though, I think you're onto something.

[–] [email protected] 21 points 10 months ago

[–] [email protected] 19 points 10 months ago (1 children)

I just see that all colors turn into pride colors in the sun

[–] [email protected] 7 points 10 months ago

Sun turns us gay!

[–] [email protected] 16 points 10 months ago

Is there any way to tell the difference between infrared reflected between (I assume) 8 and 13 microns and the infrared emitted due to absorption of shorter wavelengths?

[–] [email protected] 12 points 10 months ago* (last edited 10 months ago) (1 children)

That's not exactly heat absorbtion though. Infrared cameras capture the heat radiated by the shirts and black color is the one that radiates heat the best. That's why matt black is the worst color for a thermos and chrome is the best.

[–] [email protected] 6 points 10 months ago

If they have identical or close enough emissivity it is directly proportional to heat absorption, as given identical amounts of time in the sun and air flow, temperature will almost entirely depend in absorptivity, and emitted infrared is proportional to temperature^4.

Black bodies emit and absorb perfectly. These probably all have an emissivity that's lower than a blackbody, and very close together, while absorptivity is related to the color of the shirt. So this test is actually fairly indicative.

[–] [email protected] 6 points 10 months ago

my friends make fun of me for wearing black in the summertime but i am more uncomfortable wearing non-black than i am just sweating it out 🫠

[–] [email protected] 6 points 10 months ago (1 children)

Dang green, you hot!

Also, grey... you have betrayed us.

[–] [email protected] 1 points 10 months ago

So I saw this yesterday and I can't stop seeing things that may relate because green.

https://youtu.be/17Y82tJDk2o

[–] [email protected] 6 points 10 months ago

Just get some loose linnen button down shirts, they are fantastic

[–] [email protected] 5 points 10 months ago

What about sequined shirts? If I get the right angle I can boil a cup of water within seconds while staying cool inside. For an extra barrier I wrap my body in foil, keeps the 5g out as a bonus.

[–] [email protected] 4 points 10 months ago (2 children)

So does black make a significant difference when it's colder? Or is it only noticable when there's harsh sun?

[–] [email protected] 2 points 10 months ago

As someone who grew up in northern areas, not really. In fall or spring (Oct, or April) when the sun has a better angle you can notice. But the rest of the winter when the sun's at a slant? Not so much.

[–] [email protected] 2 points 10 months ago

It's different: radiation of long-wave infrared balanced against absorption of ambient light.

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

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

[–] [email protected] 4 points 10 months ago

Also a good indicator of why must plants use chlorophyll, which primarily reflect green light in our planet's biosphere.

[–] [email protected] 4 points 10 months ago (1 children)

I still can't get myself to wear a white T-shirt despite me wanting it.

[–] [email protected] 4 points 10 months ago (1 children)

My sweat will ruin any white fabric after the first or second wear.

[–] [email protected] 2 points 10 months ago (1 children)

Do you use aluminum/antiperspirants? I think that is what causes the staining.

[–] [email protected] 2 points 10 months ago* (last edited 10 months ago)

yup, the aluminum basically acts as a mordant for the natural yellowish stain of sweat and its microbial metabolites

best to skip antiperspirant when wearing white shirts. aluminum-free deodorant (there is no such thing as aluminum free antiperspirant, btw) can help mask BO but will not stop sweat. but if you like white shirts that's probably a decent trade-off.

zinc oxide is a decent deodorant ingredient that doesn't prevent sweating but does slow down microbes that eat sweat and release odorous compounds

avoid baking soda if you have sensitive skin as it can raise your skin pH to uncomfortable levels. ymmv

[–] [email protected] 2 points 10 months ago (1 children)

who would have guessed?

[–] [email protected] 6 points 10 months ago

Well a dog. Could guess it I mean.

If dogs can guess things, which I don’t even know if they can. But maybe.

I think maybe a dog could guess it.

[–] [email protected] 1 points 10 months ago (1 children)

How is a light gray that much warmer than yellow? Seems suspicious 🤔

[–] [email protected] 3 points 10 months ago

I guess gray is just black and white mixed, and black does not do very well

Yellow also reflects a tonne of UV and IR light. Probably helps make it so much more visible to everything than other colors

[–] [email protected] 0 points 10 months ago (2 children)

Body puts off heat too. White reflects it back, black lets it escape.

[–] [email protected] 1 points 10 months ago

The temperature of the shirt itself will have a majority of the impact on the heat transfer. Whether a given pigment is reflective in the ir is impossible to predict by eye, see below. Black shirts will warm you up more in general, though offer better protection against UV. You can however get special UV protective white colored shirts.

[–] BCsven 0 points 10 months ago (2 children)

Google says : colors do not absorb different amounts of heat, only heat from light.

[–] [email protected] 1 points 10 months ago (1 children)

Google also says to put glue on your pizza.

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[–] [email protected] 0 points 10 months ago (1 children)

Body emits infrared radiation. Sun does too. They make foil-lined jackets to reflect this heat. White shirts do it too, as shown in the image.

[–] BCsven 1 points 10 months ago (1 children)

Not according to science articles on the web. infrared penetrates regardless of colour, visible light spectrum capturea or reflects the rest.

[–] [email protected] 1 points 10 months ago (1 children)

It depends on the absorptivity of the pigment at that given wavelength. Foil for example works because in ye infrared it is still reflective. Without an infrared camera and an infrared light it's impossible to tell what the infrared absorptivity of a given shirt is by eye. The science articles are not giving the full picture.

[–] [email protected] 1 points 10 months ago (1 children)

It seems it’s still an active debate and area of research, but the answer is more complex than wavelengths and emissivity. If you want to know whether black or white is cooler in the sun, it depends on: the breathability or knit, the amount of UV hitting the skin, the amount of skin contact with the fabric, wind speed, relative humidity, how the fabric wets and wicks moisture, and more. We could look at a black trash bag and say, well it’s transparent to IR, and it blocks the visible spectrum, therefore it’s a good shirt material to keep one cool. And obviously that would be wrong. In the same way it’s wrong to say: a white shirt feels less hot when you touch it, therefore it keeps the wearer cooler.

[–] [email protected] 1 points 10 months ago (1 children)

Yes, all of that is obviously true between shirts, the question is about shirt color, which is almost entirely down to the pigments used in fabrication. In which case it is entirely due to the absorptivity, emissivity, reflectance, and opacity, of the pigment.

This isn't an active area of debate, it's an entirely empirical question or a hard modeling problem per shirt manufacturer. All of this is very solved science, and has become "an engineering problem"

[–] [email protected] 1 points 10 months ago

Well if protection from solar heat is the goal, it will be hard to beat the “chrome dome” or reflective parasol. Sometimes the ground reflects quite a bit of heat from below, like snow. Then I guess a shirt might out-perform a parasol.