Experiments to Make Self-Cooling Fabric

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In this video we follow a paper that describes achieving a daytime radiative cooling effect on cotton fabric through the growth of CaCO3 microspheres directly onto the fibers. The paper can be found here: doi.org/10.1016/j.compositesb...
My previous video in this radiative cooling series: • Making Infrared Coolin...
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Thanks everyone for watching!

[@fearisan]

Kudos for covering a "failed" experiment the way you did! It emphasizes that an outcome is a valid outcome no matter if it was negative, positive, expected or unexpected. Imagine where the world would be if scientific papers were published like that. I think I might have to join your patreon just because of this. Keep up the excellent work!

[@eugenetswong]

I completely agree that publishing negative results is very useful. His methods are very credible, which means that we can tweak his methods or just move on to something else more promising. We don't need to repeat.

[@thirtythreeeyes8624]

The testing apparatus might be flawed, it looks like the temperature is being effected by the background paint. The thicker coating the large fabric got also doesn't look nearly as good as the small scale I think it needs more treatment and agitation with more room to stir in. While it probably wont ever be as good as the paint it looked like the small scale experiment showed there is some promise if the technique can be perfected. It's also winter and even if it's only 2-3C difference in the heat instead of the 5C of the actual paint your body is going to be able to cool down a lot from that.

[@app0the]

@@thirtythreeeyes8624 inre: the winter side of things, I think a halogen fixture could also be pretty useful for the experiment since they put out a ton of infrared (iirc even more than incandescent bulbs?)

[@VR_Wizard]

The failed experiments are actually the most exciting ones. Why did it not work, what property changed from having it on a flat surface vs having it on a rough fiber like surface? Could it be that the heat rays are traped inside the rough surface bouncing around never leaving it? When using isolation on your house rough surfaces are less isolating then flat ones I have heared which would sugest the opposite of what the experiment showed because that would mean the rough surface radiates even more heat than the flat one.

[@Surms41]

That's exactly why I love youtubers that post "failure" of a positive outcome. It removes a lot of guess work :) I like Jayz2Cents* in the computer market, as well as gamer's nexus.

[@unything2696]

As a chemist with years of experience in crystallography, synthetical as well as analytical: You are doing great! There are always so many variables, but you seem to have built a good intuition already. Respect. Maybe the poor performance is due to the geometry of the fiberes? Even If the spheres reflect the light, the probability of it getting absorbed in the 3d structure of the fabric is just too high.

[@3nertia]

Hey, with your expertise, would it be alright if I discussed something with you? I have an idea but I lack the necessary knowledge to properly evaluate its viability

[@unything2696]

@@3nertia I'm intrigued already:)

[@MisterNohbdy]

that was my first thought upon seeing the results, though I'm no chemist

[@3nertia]

@@unything2696 I thought maybe, with CRISPR, glass sea sponge DNA, and DNA from a very specific fungus on Fraser Island, Australia that can turn volcanic rock into dirt, maybe we could potentially grow super-efficient solar cells that can convert way more than just UV into electricity I thought we could maybe use a similar method to grow carbon nanotube structure in various simple shapes as well ... Thoughts? Would this even potentially be possible or am I just an idiot? 😅

[@supernoodles908]

​@@unything2696I'm thinking testing different fibres might be a good idea. Cotton and plant fibres are "smooth" and don't open up much so it's hard for the microspheres to bind to it. Something like hair/wool night be good since the hair structure is scale like and can open up with warmth so you could mechanically trap the spheres on the hair

[@Impatient_Ape]

Ben is showing how to do ACTUAL science on this channel. Excellent work!

[@TheFredmac]

This is what people go to engineering school for.

[@claytonharting9899]

+

[@choahjinhuay]

Not just melting lipsticks….

[@Pyrosparker]

"Even in the failures, we're learning things" That's what separates a non-satisfactory result from a true failure; if we learn anything then it's just an extra unanticipated step towards success. The process of making something interesting and useful with home-brew is already a great thing to share, and the extra effort of trying to make it easily accessible for the average-joe is on another level that I really appreciate.

[@Pope_]

As others have pointed out, the lack of radiative cooling might be due to the geometry of the cotton fibers at a microscopic level. The chance that heat radiated from the fibers will actually exit the cloth is much lower than the chance that the heat will get stuck in the cloth and continue to bounce around. I think all things considered it may be worth trying a fabric like Denim or Silk, which has a much tighter-nit structure at the microscopic level. It might also be worth trying to apply the solution to only one side of the fabric, as denim and silk both have flat faces compared to cotton, meaning it may be possible to apply the solution explicitly to the outside of the fabric.

[@aidanwarren4980]

Denim is cotton

[@Pope_]

@@aidanwarren4980 cotton which is structured differently on a microscopic scale.

[@BIGGGY305]

what if he brushed the fabric one direction a few times? just to test

[@kbee225]

Yeah but there should still be SOME effect. There is a section of space for every thread that can emit photons back without intersecting another thread. So it should have some cooling compared to the control piece he used. But they were identical.

[@kbee225]

@@BIGGGY305 What would that accomplish? This is a woven fabric. You can't orient the threads by brushing them.

[@figueroalabs]

Cotton fibers are single cells that get elongated and stretched inside the seed pods, so this is the reason why they look kinda like transparent plastic straws, or like transparent long tubular leafs of grass (which are multicelular, I'm just saying they look alike).

[@drworm5007]

Mammalian hair is also transparent when not pigmented. I have a long beard and have often noticed the lighter coloured hairs are clear. It's not surprising to me that cotton fibres would be the same.

[@cineblazer]

We're one step closer to the mythical pillow that's always cold on both sides. Keep up the good work, I salute you 🖖 EDIT: even if it didn't work as well as you hoped, I bet you find a way to fix it. If there's one thing I've learned from watching this channel, it's that it's never a good idea to underestimate NightHawkInLight!

[@wingnutbert9685]

😁👍👍👍 Once perfected, then coat in his water proofing mix and we'll have sweat and body oil proof pillows too!!!!

[@deepbluetree]

This is what dreams are made of! 😍

[@deepbluetree]

This is what dreams are made of! 😍

[@Emolovesblack28451]

Don’t forget to link your other videos that you’re referencing! You’re the reason I joined patreon and I’m so proud of you. Your experiments are useful and interesting, and your processes are consistently well documented. Well worth crowdfunding.

[@Nighthawkinlight]

Thank you!

[@Skapo]

As a Texan, I approve of this research. 🔥🔥🔥

[@custos3249]

Especially after your state denied the right to water breaks

[@ugwuanyicollins6136]

As a Homo sapien sapien I approve

[@jessehunter362]

@@custos3249the cooling fabric don’t really help that all that much

[@grugiv]

it's nice when the power doesn't go out

[@jessehunter362]

@@grugivTbh as long as you manage things properly it’s fine even when the power does go out- i didn’t have ac for the first decade of my life

[@Jmr2urbo]

This would be great for hardhats too. They trap heat and get very uncomfortable over time. Even if you had to reapply every now and again if it keeps my head cool it would be a game changer.

[@Nighthawkinlight]

My current paint could go on a hard hat as is. I'm thinking about trying that soon just to get one practical item made to test out

[@stephenrosenthal5252]

I too wear hard hats. Not everyday but sometimes. My thought was that they are keeping the body heat in. Not absorbing the heat from above. I mean moat of them are yellow or white anyway. My guess is that a test with your paint on the hat with no ones head in there might look like a success. Just for some one to put it on at work just to have it feel the same as with no paint. I think i feel like i saw a fan that could go in the hat. That along with some vent holes might be a better option.

[@TheFredmac]

Where this concept is most needed is in power line tree trimming. You can't have vents in your helmet working around power lines. If you can show that this helps cool a helmet I know people who would want to hear about this.

[@stormthrush37]

​@@NighthawkinlightI'd definitely like to see that as your next video!

[@babybalrog]

@@Nighthawkinlight My understanding is that you can get surplus hardhats for the cheep. They are only rated for 5 year lifespans so companies are constantly throwing away old ones.

[@Coldzillaa]

I love this CaCO3 series, i'm in the last year of my chemistry masters and my project this year involves synthesising CaCO3 microspheres (vaterite) for drug delivery purposes. I'm hoping to apply for a PhD with my current supervisor and exploring new applications. This work is excellent and i'm looking forward to seeing more!

[@Nighthawkinlight]

Very nice! I've read some about drug delivery uses for the microspheres. Are you mostly looking to absorb chemicals into solid microspheres or are you making hollow ones? I've been interested to try some modifiers to my microsphere recipe to see if I can reliably make them hollow. Sometimes a few of them are hollow just by chance, but additives like guar gum are supposed to help form them that way on purpose.

[@hiperkinetico2011]

@@Nighthawkinlight Being able to generate drug delivery would be interesting. Liposomes are currently used for drug delivery. Are these calcium carbonate spheres not toxic at all?

[@cardboard8206]

Your failures only show your successes to be that much more legitimate. In the world of sensationalism, your honesty is invaluable. Well done!

[@putteslaintxtbks5166]

Back in the 1970's or 80's I started seeing things that changed colors by temperature like mood rings and digital temperature strips for monitoring aquarium temperatures. If a roof/exterior could change to a dark color in winter and a lighter color in summer, it could make a big difference in heating and cooling a house.

[@ugwuanyicollins6136]

Are you I your late 60's

[@putteslaintxtbks5166]

@@ugwuanyicollins6136 Yes. Will be 67 on Monday.

[@DavidSartor0]

@@ugwuanyicollins6136 Why do you ask?

[@ugwuanyicollins6136]

@@DavidSartor0 they where alive during the 70's

[@DavidSartor0]

@@ugwuanyicollins6136 Thank you for responding. Obviously they are in at least their 60s. Given that, why did you ask?

[@nicholasswaffordece1215]

Thank you so much for posting this to the public. You are a true hero!

[@handyreiter1310]

Unimaginable that this kind of work was once attributed to universities! ❤❤❤

[@aufoslab]

SAY MY NAME!!!

[@FireNLightnin]

I've been watching for over a decade and I didn't even notice your videos getting longer. I'm always just so happy to be learning along with you.

[@MrAlFuture]

I, for one, really enjoy the longer form videos that cover a full project story arc like this does. I appreciate that it may not attract as many views, but they are really enjoyable, satisfying and inspiring to watch. Thank you for sticking with it and not giving in to the algorithm.

[@uhitsethan]

it might have more to do with the texture? when light bounces off a strand of fabric, the light isn't likely to bounce in the direction of space, but rather into another strand, then into another strand, etc.

[@Roshkin]

I want to see him try treating a sheet of cellulose to see if it responds any different.

[@TeamRiceUSA]

Exactly ! Just what I thought. Paul

[@FLPhotoCatcher]

@@Roshkin You mean paper?

[@tylerswan491]

Exactly my thought. If any photon bounces off a sphere it could go in many directions. Especially if it hit a bottom fiber. Now that photon bounces up and hit the bottom of another strand and now its bouncing around inside the fabric instead of escaping in a few bounces like a flat sheet if paper or something. (I dont know science)

[@papydoctor]

Yes, i was wondering also about the sample depth, front bouncing/emitting is ok but what happens at the middle/back of the sample?

[@Rubikorigami]

Plant fibers like cotton are relatively finicky to dye and coat. Maybe you could try with wool : its fibers have little scales that can be lifted by chemical processes and trap the microspheres.

[@FLPhotoCatcher]

I like that idea - too many synthetic materials in our world that make toxic micro-plastics. And the wool market could use the help.

[@JP-xd6fm]

It will be funny saying in a hot summer day "I'm going to wear the wool shirt today, it's very hot out there" lol

[@VoidVagabond]

​@@JP-xd6fmmerino wool is typically pretty breathable and moisture wicking, so in that sense it would be an acceptable summer fabric.

[@JP-xd6fm]

@@VoidVagabondOh I didn't know, wool is used only in winter in my country

[@VoidVagabond]

@@JP-xd6fm my country too I reckon, I've just been researching fabrics and merino wool came up. Merino is a special kind of wool that is softer and finer and stronger compared to other wools.

[@IdRatherBeMaking]

You may want to consider stirring the solution and cotton test piece under vacuum. You may have fibers that are bordering or surrounded by trapped air. That may be causing your lack of spheres on some fibers.

[@Adskdnweotland]

good point! maybe adding a surfactant could help eliminate bubbles during stirring

[@richvasquez8960]

my wife has watched you for years and was raving i should check your channel. i think i will be raving about your channel more than she does. extremely impressive content. what an exceptional teacher. top notch sir!

[@TriAngles3D]

He consolidates so many areas of interest... Things that we would want to look into but usually never seem to get around to. And, then he takes it to another level.

[@aquelaquelaquelaquel]

This is what education should be about... I am amazed with the quality of this content and long dedication. Love your work! You and VSauce are my favorite content on Ytube. I really loved the ride and the fact that even though the results were not so promising.. it is still uploaded so we can learn and live the discovery and a-ha moments!

[@paulwright8378]

You should view movie recaps 😂

[@noahoverholt4145]

A infered heat lamp may be a good way to create consistent test conditions.

[@pastabreaker4385]

he has studio lights. Even those should put out enough light

[@lostboytnt1]

There's been a growing trend for many creators to make longer videos lately, and most of them I'm just not interested in investing the time in watching them, you are an exception. If your videos are 30 seconds, or 2 hours, I'm still excited to watch every one. For those who may not have the interest and attention span as I do, maybe fill in some gaps with shorter simpler, and easier to produce (fluff?) content? While taking some of your valuable time, it may free up some of the burdens and allow you to put more time and effort into longer experiments.. Regardless. I love all you do, and often share your stuff with people I think would be interested!

[@gtjack9]

I do much prefer videos like this to be longer. I mostly watch 8-15 minute videos on average. A video like this I’d happily watch up to 30 mins at a time and happily soak up a series of videos, part 1, part 2, etc

[@mineton1293]

always a good day when NightHawkinLight uploads

[@MaxWithTheSax]

It is really cool to see the microspheres stuck to the fibres under the microscope. One thing I am wondering is what the expected result on the thermal camera should be. Since the coated surface radiates more shouldn't we expect it to show up warmer on the thermal camera? Maybe the difference we see is due to the insulating properties of the fabric versus the painted tiles.

[@Nighthawkinlight]

These coatings don't radiate *more*, they just radiate at a particular wavelength. If the radiative properties are working they will cool down, and the IR radiation follows the same downward trend with temperature as anything else causing the camera to read them as colder. I've checked the IR readings in past experiments and compared with thermocouples to see how much variability there is between camera readings and actual temp. When reading differences in temp between two samples in the same frame it's very accurate, unless trying to measure a very dissimilar material like paint vs polished metal.

[@RandyCampbell-fk3pf]

​@@Nighthawkinlightit might be that the cotton itself is just too insulative

[@Rin-qj7zt]

@@Nighthawkinlight any way to confirm the wavelength they are radiating at? only thing i can think of is that either the cotton doesn't transfer it's heat very well to the coating, or the structure of the fibers woven into a fabric does something to counter the cooling effect, like trapping radiating light. how well would the coating absorb the wavelength of light that it emits? in woven fabric, would the majority of fiber surfaces be more exposed to a path to direct air or to other fibers?

[@Nighthawkinlight]

@@Rin-qj7zt I have a plan for more accurately determining the IR wavelength that I might play with in a future video

[@CrustyBiker]

I speak as a simpleton who doesn't have any scientific knowledge but I'm just wondering if it's possible to get the crystals or whatever it is to grow on the sunny side only by maybe pat pressing the solution on or putting into a fast flowing river of solution one way, the reason being is that I wonder with all the fibres coated with spheres then the UV rays from sun might hit some sideways clinging spheres and bounce off each other like disco balls which reject the rays but bounce off each other towards the skin, can you view how much light gets through on a treated piece compared with a control piece? Also I gather that the wicking cooling is to do with convection heat drifting away like heat from a radiator and the UV emitting heat loss is like heat lamp which should be able to.still radiate out through the plastic sheet is that right!?..

[@cleanroomwizard2356]

This is phenomenal work and I do appreciate that you provide the "null" result - something most scientists don't even bother publishing. It honestly saves so much time for others as well so they don't think that they are crazy or just doing something wrong. The key here is that everything is transparent to IR if it is thin enough and the amount of reflection of visible light and near IR may be not sufficient with these coatings (given that you had quite thick paint layers earlier to get ultra white cooling effect). As someone who has actually tried and replicated your pigment recipes, I deeply appreciate the level of detail you are putting into this series and my last suggestion is to consider that perhaps the amount of energy lost to space/cooling effect is completely dominated by conduction/convection to the air in your chamber due to the massive surface area of the fabrics compared to the painted panels (so you just end up seeing near ambient temperatures). That is another factor beyond just the actual pigment properties - a complex question with multiple possible answers.

[@Nighthawkinlight]

Thanks for the effort of trying my recipe! Did it work out for you?

[@cleanroomwizard2356]

​@@Nighthawkinlight Yes, it did! I have been trying to get smaller spheres than the standard recipe because the scattering efficiency is best when particles are approximately the size of the light that you are trying to reflect (so I would prefer spheres in the range of about 0.5-2 um to compare) but I don't know if it is the gaps or the particles that will dominate that behavior. I am going to try to add extra nucleation sites with a bit of fumed silica and a much more dilute solution to try and reduce sphere sizes. It is a project that is actively being developed this winter. I think a different polymer binder with more elasticity is also on my to do list. I greatly appreciate your heavy lifting in the other aspects of this work!

[@Nighthawkinlight]

Thanks for the report! I'll also be working on reducing sphere size soon. The first idea I'll be trying is increasing the citrate to lengthen the effective window where stirring time creates nucleation sites. You might then be able to effectively stir between 30min-1hr instead of 1-10min. You should also read the paper I link to in my previous video about size controlling the spheres. They had some interesting methods using I think ethylene glycol

[@cleanroomwizard2356]

@@Nighthawkinlight Sounds promising! I definitely think that has potential and will go in more depth in some of these alternative methods to tweak the formation/size of the crystals. My blender size isn't quite right for making large batches yet and I may try to invest in some type of centrifuge or else settling times of the smaller particles would be far too lengthy to be practical. I'll look forward to your next video on this topic and hopefully I'll have some interesting results to share too. Regrettably KZbin doesn't like links in comments to share other work/information but there are some other papers on these cooling materials to help determine predict best shapes and sizes of gaps/particles. The manufacturing difficulty, costs and durability tends to be the primary limit in my experience.

[@LeruaEcke]

yes i wanted to add a comment about this reflection too, so i just want to add that in many ways the fabric is not directly comparable with the painted plate. For example because the fabric has a different surface, and a different heat capaccity/ transport..

[@danielhakamaki7678]

This story is such a rollercoaster. I was on the edge of my seat. Emotionally engaged by a damn chemistry video! I actually said "Noooo!" out loud at the reveal of the last experiment. In my own headcanon, "Electricity Free Air Conditioning" is the first part of a trilogy. It brought such new hope. Could this finally be it? A (partial) solution to a warmer climate AND rising energy costs. Why isn't everybody using this already? It's so clever! Then came the highly anticipated sequel, "Experiments to Make Self-Cooling Fabric", or as I have come to think of it "The Entropy Strikes Back". It was glorious. Jam packed with excitement, drama, ups and downs, glimmers of hope swiftly dashed, and an ending with both a punch in the gut and a thrilling cliffhanger .With pounding heart, after the video finished, I had to calm myself down. Of course it was to be expected that our hero should face fierce resistance, that the forces of darkness (or in this case hotness) must seem almost insurmountable. It's basic storytelling practice, so don't sweat it. If I know anything, it's that the hero always wins in part three. Really looking forward to "Return of the Infrared Dye".

[@Azyx90]

Note about the texture of the treated cotton. Pure cotton changes drastically when washed with too hight of a temperature. Cotton turns into more coarse and chalky feeling. It's easy to ruin t-shirts or sheets by accidentally washing them with too hot setting in the washing machine.

[@user255]

They are not ruined by it. Just wash them again with some softener.

[@R-Tex.]

As always, amazing work! I just wanted to say that you should watermark your original footage (e.g., the shot of the coated fibers), like Steve Mould does.

[@Cyanid3Child]

Best science channel on youtube.

[@adambruley5242]

You are Absolutely my HERO!!! We all love you... Keep us Experimenting and Learning

[@arnavjain7564]

Maybe the result is due to the thermal mass of just the cotton being too small which is why they can't retain their coldness or are easily heated? In comparison to the coating which looks like it is done on a tile or some wood piece... I'm not sure if i can get the point across with this but i hope it sort of makes sense?

[@TheFredmac]

I agree.

[@MrBrew4321]

One way to think about that is to imagine opening a freezer, everything in there is the same coldness. But if you pick up a loaf of bread in one hand and a bag of frozen peas in the other hand the peas are more likely to freeze your hand because of their thermal mass. Idk what the energy flows are in that experiment but it is certainly plausible that the cloth is like the bread and can't "retain its coldness" there I explained your thought I hope :D

[@petersvideofile]

Fantastic work man. I love your enthusiasm, and the depth you get into, all while keeping your work understandable and accessible to anyone!

[@aserta]

If there's one thing i love about NHL videos above all else, it's the approach. Find a topic, figure the basics, try something. Doesn't work? Not a problem. Find new solution, apply. Success. One of my OG subs and by far the one that makes me smile when i find an upload in the subs.

[@johnnymcgeez5647]

I dont know if you will ever see this comment but i just gotta say thank you for your videos. Internet is so full of garbage and sludge and there are people with dark intentions, but people who make content like you are like the shining light.

[@blurglide]

I have a "cool" radiative cooling anecdote for you! Last weekend, I took the black soft-top off my Jeep. I thought I'd hose the dust off before storing it for the winter. My grass yard slopes slightly to the northeast with an unobstructed view of the sky, is shaded to the south by my house and a large tree, and the outdoor temp was 45 degrees. An hour later, I discovered that the mositure on the fabric had FROZE, and the outdoor temp had only dropped to 43! For similar reason, this portion of my yard retains snow for many days longer than anywhere else in my neighborhood. I've had tiny patches of snow around on days where the temp approaches 60, although not for long.

[@Nighthawkinlight]

The effect you noticed is actually responsible for some occurrences of black ice that occur before other things freeze

[@chrissscottt]

Very interesting, thanks. A frustrating result but I admire your tenacity and resilience.

[@gooball2005]

Man, great video as usual! I love that you're not only exploring interesting topics that don't seem to be talked about all that much on youtube, but that you're also deliberately designing procedures that could be replicated in a garage without the need for specialised equipment. Respect!

[@LeAbstracted]

Thank you for sharing all of your experiments and projects over the years! I've enjoyed every single one and look forward to whatever you might have planned next!

[@B_Van_Glorious]

The legend returns! Seriously, love your work Nighthawk, you're an inspiration to all us everymen out there

[@h7opolo]

If you compare black shirts, one treated, one control, you will see the difference you expect because white fabric already has near maximum reflectivity. Give it a shot.

[@Zeusbeer]

if you treat a black shirt, it becomes white

[@h7opolo]

@@Zeusbeer true. I guess, the effect he needs is not reflectivity but thermal conductivity as well, not to mention the texture of the fabric would be unpleasant.

[@craftminerCZ]

I love how you explain every step so clearly I almost feel like I'm inventing this myself. Honestly an impressive teaching ability on top of the innovative mindset.

[@justinbanks2380]

I love your community! The fact that you cover pretty in depth topics and yet still say something is over your head and reach out to your viewers (knowing you have a great community and knowledgeable) 😊

[@wonjez3982]

I like how in chemistry roughing up a surface can be as easy as boiling it in some acid/alkaline solution. You just got to apply what you know and combine the steps. Epic results and procedure!

[@LiveWire937]

what about a flow-through treatment process? you'd need some custom-built kit for it, but nothing too complicated; I'm picturing a shallow box wide and long enough for the article of clothing being treated to lay flat in, a mesh grating inside to keep the piece off the floor of the box, drainage slits below that leading to a heated basin with a sump-pump in it, the outflow of which would be plumbed to the lid of the box which would basically be a jumbo-size shower-head, with a thin chamber inside and an array of holes in the interior surface.

[@Nighthawkinlight]

Interesting idea

[@LiveWire937]

small addendum: might need to do some tests to see if the temperature of the fabric itself matters or not respective to the fluid at the start of the process. My hunch is that variations in the fibers' thickness and the density of the weave would make some parts take longer to heat than others, resulting in uneven etching and therefore an uneven coating of micro-spheres. If this is the case, it might be worthwhile to start with just a known amount of warm water in the basin, run it for a bit so everything in the box gets up to the ideal temperature, then add a concentrated solution such that it mixes via the pump and dilutes down to the desired mixture.

[@ThingsWhichArentWork]

Thank you for sharing your work and your results.

[@jacobrobinson7395]

I absolutely enjoyed your content. I’ve played a round with your last video’s experiment and can say it absolutely works. Can’t wait for the next video.

[@TeamRiceUSA]

I think what you mentioned is a resonant spheres size. I think near infrared frequency is the key and on a flat surface. I recently was amazed at the frost on my car roof, which had a melted pattern as the reflected sunlight from a window traveled across it. Surface or covelant bond that rejects or reflects a particular frequency of energy is the key. Try your paint on glass and on handiwrap plastic coating stretched tight. Paul Rice , Hemphill, Tx

[@RumbleGroove-official]

cool how you are able to make this kind of stuff

[@notsonominal]

Cool stuff, like litterally! Thanks for following up the paint video with this, super interesting!

[@crestofhonor2349]

This is such cool stuff and seeing how the paint keeps stuff cool is fascinating

[@asteliaz]

I'd be interested to see how the breathability of the fabric has changed with this process, because you mentioned the gaps got smaller. I feel like, as a t-shirt, any cooling that would've come from allowing air to pass through might off-set the theoretical additional radiative cooling. Might need an experiment where the cotton layer sits on top of a thermometer in different conditions, sunlight with wind vs sunlight with no wind.

[@topspeed250k5]

Good point...but allowing air to pass through the fabric only cools the skin by evaporating moisture from the surface of the skin. He discusses that the paper reports that the wicking of the treated fabric is enhanced, so evaporation and cooling is better by that secondary method. i.e. there may be less air directly getting through to the skin, but the moisture is being more effectively evaporated so more cooling occurs. Definitely worth testing. I guess to separate the evaporation factor from the radiation, that temperature test would have to be done in the dark.

[@Jehty_]

That shouldn't really be a concern for a practical application. Just use a fabric that has larger holes.

[@asteliaz]

@@Jehty_ fair point! But if my thought process holds any truth, and applying it to an existing t-shirt does reduce the breathability, it'd be good to know :)

[@TheFredmac]

I think that wicking is more important than air flow through the material when it comes to cooling. I have worked outside for a couple decades, but this is opinion not anything I have tested.

[@WeighedWilson]

I would think you'd went moisture evaporating on the skin to absorb heat from the skin instead of on the fabric to absorb heat from the fabric. Humans have the advantage of sweat cooling over animals with a heavy pelt because the sweat can rapidly evaporate in the air thereby pulling heat from the skin. A heavy pelt hinders airflow and therefore hinders evaporation.

[@Dalorian1]

Perhaps there are an optimal number of spheres per area of thread? more that that number and its ineffective, and less that that number and it becomes ineffective?

[@phlanxsmurf]

Love the full on experiments. Awesome video. Thanks!

[@BeckJoseR]

Always excited when I see a new video by Nighthawk. Thank you for all that you do! And even in the failures we can still learn. Great work!

[@NickCombs]

I wonder if it might be possible to improve the durability of the painted surface with what you’ve learned here. If so, maybe it’s possible to create a sort of flexible material out of many tiny rigid surfaces that apply the paint in a way we know should work.

[@fire17102]

Do you think maybe a ultrasonic cleaner could be used to stir bigger batches more effectively? Also, im sure with some more clever optimizing youll figure it out! Amazing work

[@linecraftman3907]

Doesn't it disintegrate stuff via cavitation?

[@TheFredmac]

Have you ever seen a non Newtonian fluid in a bass speaker? A cooking sheet over a couple of bass speakers might do what you're talking about.

[@zwmmxviii6851]

Thank you for sharing not just the results, but the process. I'd much rather learn from an unexpected failure than from expected success. Your process and logic when addressing problems is brilliant. Keep up the great work! 👍

[@recklessroges]

Thank you so much for posting this important milestone. I'm sure that this will have created many useful conversations.

[@Ripen3]

Cool project! I really want to give it a go, but since half of those chemicals are illegal in Norway(otherwise people would consume them and die) I'll have to settle with watching. Thanks for sharing though! That's what I love most about your channel, you're all about sharing so we can all learn and evolve. A rare trait unfortunately.

[@TheFredmac]

I have heard Norwegians where GOATs. Which I assumed ment you are the greatest of all time, not that you would try and eat everything.

[@mduckernz]

… wait, which of these are illegal?! There’s plenty of people doing chemistry in the EU, and with much more dangerous chemicals than this

[@PraxisPragma]

Who else also 👍the video before even watching it?

[@htmagic]

NHL, very interesting video! Another trick from textile mills is to treat the cotton cloth in a weak caustic along with the warm water. The alkaline soda may do this too but the caustic swells the cotton fibers and allow it to accept the dye better. Wash the caustic before treating it with the solution. Good luck! Cheers!

[@mrchangcooler]

Being able to see what you're doing helps so much in better understanding what you're doing, and having ideas to solve the issues. So many things seem complex and requiring a lot of mathematical knowledge to engineer and change physical things to do what you want, but all it takes is physical intuition and seeing what you're doing physically. The world of the big makes just as much sense as the world of the small.

[@georgvoldemartomusk1538]

"Nice Science Man Tries to Make Cold Hat"

[@SHRUGGiExyz]

I'd be curious as to how well this type of coating would stand up to wear, if you'd need to reapply the coating often as the fibers rubbing together during regular wash cycles could kick off some of the pigment. When you mentioned coating polyester fibers in silica nanospheres it got me worried about the possible risks of silicosis assosiated with wearing something like that daily. It stands to reason any particles coating a fabric would be shed to some degree, and small silica particles coming off your tshirt into the air you'll be breathing seems like it may be a health concern. I'm no expert, though, maybe it'd be such low amounts it's under safe exposure levels even in manufaturing settings (ie cutting and sewing this type of fabric) I also wonder how much of the radiative cooling effect is gained by your original paint simply by having one flat outer surface doing the reflecting. IR being sent off the shirt only needs to be done on the outside, so apart from the sweat wicking you mentioned briefly, you might have better luck with a sample with only the outer layer coated. I'm imagining a similar process to your t shit bleaching, but by airbrushing part B onto a shirt presoaked in part A of the mix? Someone else also mentioned the geometry of cotton fibers simply being too microscopically fuzzy to really radiate heat effectively, so screenprinting patterns onto plain and treated shirts to give you an idea of how they differ. Plus, the ideal spots have to face the open sky anyways, so painting just the front, back, and shoulders would be the most efficient places to coat for the IR cooling effect. Get an IR transparent acrylic binder and paint yourself an IR cooling vest, and that would be a fantastic success!

[@NFTI]

I love this series

[@SeegerG]

You're awesome. There are few with your skill and style. I haven't been thinking along such lines at all but you make it very inviting. I've always appreciated your good work man keep it up!

[@benkirkland5354]

Love this soooo much. Could it be that the air gaps between fibers are acting as an insulating barrier? Or could it be that since the fibers are cylindrical(ish), the infrared waves aren’t being directed outward as from a flat(ter) surface like the paint; they’re bouncing back and forth between them, thereby heating the air space between? Very interesting work as always!

[@MacroAggressor]

I don't recall seeing the microsphere structure within the paint under magnification, but I suspect that as a result of the paint curing while the spheres are in suspension -- whereas the CaCO3 crystallizes on the threads -- there may be a significant difference in the reflectivity between the two. This might have actually resulted in a possible _reduction_ in reflectivity compared to native bleached cotton (I have no numbers to support this, only a hypothesis). I'm sure there is a viable method to deposit the microspheres in suspension to prevent the recrystallization to test this (even if the testing method rendered the fabric unsuitable for clothing purposes, such as a very, very thin resin suspension).

[@ZeroPlayerGame]

Possibly just controlling for exposure time and washing the excess off before it has the chance to join crystals could yield some results.

[@topspeed250k5]

Yes, he jumped from 1 treatment to 3, and ended up with a cracked crystallised layer Maybe 2 treatments would be a sweet spot? A thicker layer but still discreet spheres...maybe.

[@MacroAggressor]

@NightHawkInLight ya know, on thinking further... the simpler way forward would be to just test the reflectivity of the samples vs the native cotton (ie. eliminating the effect of the CaCO3 heat shedding). If the reflectivity of the treated samples is notably lower, then that would be a solid indicator that this might be the confounding factor. I don't recall if you have a precise luminance measurement method (yet).

[@ZeroPlayerGame]

@@MacroAggressor just put em as a bottom in a black box and use the bog standard luminance measurement in one hole up top with an LED in the other. If you're looking to compare, not get exact numbers, it's not a hard setup.

[@MacroAggressor]

@@ZeroPlayerGame Good point, the real relevant measurement is the comparison, not the absolute value. At least it's a jumping off point to determine if further, more accurate testing is called for.

[@JacquesDV100]

I am really excited about this project, and just everything you do in general. Big fan

[@JATmatic]

This an rare channel where the quality actually goes up.

[@id104335409]

The Arabs will make you a statue of pure gold my friend! Pursue this further!

[@jaogileme7082]

damn i'm literally trying the same type of research after i saw your first video but my aproach is coating the fabric instead of growing the spheres inside of them, things have been slow for me since i don't have a microscope but if i get somewhere interesting i'll try to reach out

[@huraqan3761]

Incredibly interesting video as always. Meticulous process, great explanations, thanks man!

[@Respectable_Username]

Love that you're publishing your null results too! We can't move forwards with science if we can't figure out what _doesn't_ work too ❤

[@1chumley1]

Man, you figure this one out and you're rich.

[@PedroCarvalho-bk4yn]

This is one of the most interest projects I've seen.

[@Arcelux]

Ben you have one of the few channels that help the world in more ways than you know. Keep it up!

[@Les__Mack]

Thanks for another great video. I always look forward to them.

[@mrtavetski1859]

That was phenomenal! One of the best videos ive seen on KZbin in months. Thank you!

[@Grandwigg]

I for one quite enjoy these longer videos. I hope continued content in this format remains viable.

[@gutsngorrrr]

Really interesting topic, I hope you keep going down this rabbit hole

[@pablopenasco4254]

I love this research. Thank you for continuing!

[@ThistlesGarden]

Great video, nice to see all the work you did to give the experiment the best shot you could.

[@ianwise2457]

cool! im always excited when a new video arrives

[@Felenari]

Awesome watch. Thank you for sharing.

[@GM-gh4dk]

I'd love you to continue the experiments on fabric, including synthetic fibers which are quite commonly used.

[@scott98390]

You sir, are an excellent scientist. Fantastic experimental process.

[@eddypoletto1852]

The coolest channel ever! Thanks, man, you're great!

[@mikemichelizzi2023]

Thanks for sharing this despite the disappointing results. Your experiments are always interesting!

[@alphanaut14]

Will someone get this guy nominated for a MacArthur Fellowship? Ben, your constant genius in exploring and sharing new topics in practical science constantly blows me away. I'm a patron now, but that is nowhere near enough for you to properly explore these subjects.

[@scottrussell8465]

At 12:30, thank you, I was yelling at the screen that the agitation might have been enough! Thanks for satisfying that curiosity.

[@stevenboelke6661]

Your channel has really matured like a fine wine. Thank you for your contributions to this platform.

[@AdemVessell]

Amazing work and video and presentation. Fascinating project!!!!

[@Sirzerty]

Thanks for doing the ad with your parrot all the time. It's my wife's favorite part! I've been looking into a lot of what CaCO3 can do thanks to you, and managed to save a lot of money this year by using hydrated lime to neutralize acid in my wood boiler vs using the manufacturer's propertiery unlabled powder that costs $30 a tub. Plus I'm planning on making mortar (lime putty based) comparing eggshells, hydrated lime, and high calcium lime (heating and slaking eggshells & hi cal lime, just salking hydrated lime)...and building the base of a greenhouse and small goat shed with them.

[@hesthatguy]

Super interesting subject material. I look forward to seeing more.

[@WayneEveland]

Thanks for being you. It’s people like you that make me proud to be a Michigander. Me and my young daughter love to watch your videos and it always sparks us to try more science experiments!

[@szplai]

Really fun video. Thanks for sharing.

[@davisbrowne1906]

Amazing work. So fascinating.