Purdue researchers develop a very white paint that could one day be used to cool buildings

Shawn Knight

Posts: 13,080   +131
Staff member
In a nutshell: Engineers at Purdue University have developed what’s being described as the whitest paint ever created. The new paint, which outperforms a formulation crafted late last year by the same team, is believed to be the closest equivalent of the blackest black, a material known as Vantablack.

Last year’s white paint was capable of reflecting up to 95.5 percent of sunlight but the new variant pushes that figure to 98.1 percent.

The paint is comprised of a high concentration of barium sulfate, a compound commonly used in photo paper and various cosmetics. The team also discovered that using barium sulfate particles of different size allows the paint to scatter more of the light spectrum from the sun, contributing to its high reflectance.

Bragging rights aren’t the only thing at stake here. The paint, which has been in development for six years, is also very good at keeping surfaces cool.

In testing outdoors, the team’s paint kept surfaces 19 degrees Fahrenheit cooler than their ambient surroundings at night. Under strong sunlight during mid-day hours, surfaces were eight degrees cooler than their surroundings. And when testing in a wintery environment with an ambient temperature of 43 F, the paint still managed to lower the surface temperature by 18 F.

The researchers have filed patent applications for the material and appear set to commercialize it in the future.

Permalink to story.

 

Crinkles

Posts: 114   +111
"A thin layer of barium sulfate called baryta is first coated on the base surface of most photographic paper to increase the reflectiveness of the image, with the first such paper introduced in 1884 in Germany"

Yeah uh invention, taken direct from Wikipedia.
 

negroplasty

Posts: 536   +30
Yes, let's make everything super reflective... let's paint some sweet concave surfaces white while we're at it. What could go wrong?
 

Farkinell

Posts: 138   +207
Maybe they will come up with a formulation of the paint that contains TiO2 - which is used in self-cleaning coatings. https://www.researchgate.net/public... and bacteria deposited on the coated surface.

TiO2 is generally the pigment of choice for all white paint anyway, including cosmetics and all sorts of paints.

Regarding self cleaning surfaces such as superhydrophobic coatings, these tend to only be useful when a) the surface is mounted at an angle so the droplets can physically roll off, so not too useful painted on a flat roof, and b) the UV catalysis cleaning mentioned only works for organic dirt such as bird crap, bits of leaves bugs etc. Inorganic dirt such as sand, minerals in soil etc will just remain as it is on the surface, blocking the light reaching the panel.


 

Avro Arrow

Posts: 1,142   +1,270
TechSpot Elite
This "whitest paint in the world" is one of the worst wastes of time and money that I have ever seen. If there's one thing that we all know, it's that nothing that is white, stays white for very long. It's like when Ric Flair said "Being the man, and staying the man are not the same thing!" (Sorry for the low-brow wrestling reference but it was the best that I could think of on a Saturday morning.)

Here's a better idea. How about just putting actual mirrors on the tops of buildings that reflect 99.999% of ALL LIGHT? It bet it would cost less and be far easier to maintain than trying to keep white paint white in our polluted cities.

This "mega-ulta-uber white paint" would be like using the "Space Pen" while just using actual mirrors would be like using a pencil (I do believe that everyone here knows about that debacle).

Real mirrors would be cheaper, faster to produce, perform better, have better reliability and ease of maintenance.

Of course, that won't make anyone rich so they keep coming up with crap like this. It's the same reason that the Pentagon got LockMart to build the F-35 instead of just building thousands of F-16s which would have otherwise been far more potent and cheaper.
 
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Irata

Posts: 1,361   +2,171
So that‘s what Ed Sheeran is using....and Coca Cola probably won‘t.

Seriously, painting a vehicle with this paint and Vantablack would probably look pretty rad.
 

wiyosaya

Posts: 5,786   +3,994
This "whitest paint in the world" is one of the worst wastes of time and money that I have ever seen. If there's one thing that we all know, it's that nothing that is white, stays white for very long. It's like when Ric Flair said "Being the man, and staying the man are not the same thing!" (Sorry for the low-brow wrestling reference but it was the best that I could think of on a Saturday morning.)

Here's a better idea. How about just putting actual mirrors on the tops of buildings that reflect 99.999% of ALL LIGHT? It bet it would cost less and be far easier to maintain than trying to keep white paint white in our polluted cities.

This "mega-ulta-uber white paint" would be like using the "Space Pen" while just using actual mirrors would be like using a pencil (I do believe that everyone here knows about that debacle).

Real mirrors would be cheaper, faster to produce, perform better, have better reliability and ease of maintenance.

Of course, that won't make anyone rich so they keep coming up with crap like this. It's the same reason that the Pentagon got LockMart to build the F-35 instead of just building thousands of F-16s which would have otherwise been far more potent and cheaper.
No inexpensive mirrors achieve reflectance as high as 98.1. Multi-layer dielectric mirrors, such as those found in lasers, are about the only ones that can achieve anywhere near that reflectance value. Some of those mirrors achieve even higher reflectance but, simple "aluminized" mirrors only achieve a reflectance value somewhere in the range of 93%. What makes aluminized mirrors appear to have a higher reflectance is the type of reflectance they exhibit - Specular Reflection - https://en.wikipedia.org/wiki/Specular_reflection Multi-layer dielectric mirrors, however, require expensive coatings in expensive vacuum chambers and would never be economically viable in large sizes and mass-produced. They also typically have a very narrow range of wavelengths that they can reflect that well. The paint that they are talking about here exhibits diffuse reflection. https://en.wikipedia.org/wiki/Diffuse_reflection

TiO2 is generally the pigment of choice for all white paint anyway, including cosmetics and all sorts of paints.

Regarding self cleaning surfaces such as superhydrophobic coatings, these tend to only be useful when a) the surface is mounted at an angle so the droplets can physically roll off, so not too useful painted on a flat roof, and b) the UV catalysis cleaning mentioned only works for organic dirt such as bird crap, bits of leaves bugs etc. Inorganic dirt such as sand, minerals in soil etc will just remain as it is on the surface, blocking the light reaching the panel.
Since you seem to know so much about it, why did you not think of this earlier?

Eastman Kodak made a coating from Barium Sulfate long ago that was considered the "gold standard" for "white" https://www.labsphere.com/labsphere.../spectraflect/6080-white-reflectance-coating/

If TiO2 were capable of achieving the level of reflectance that they determined that Barium Sulfate can, they would have chosen that instead. They did, however, do months of research on this. How much research did you do?

:rolleyes: I think it is interesting that most of the posters to this thread seem to think they have more knowledge and a better tack. These researchers have shown that they accomplished what they had set out to do - make a coating that would cool the surface under virtually any temperature conditions.
 
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Crinkles

Posts: 114   +111
No inexpensive mirrors achieve reflectance as high as 98.1. Multi-layer dielectric mirrors, such as those found in lasers, are about the only ones that can achieve anywhere near that reflectance value. Some of those mirrors achieve even higher reflectance but, simple "aluminized" mirrors only achieve a reflectance value somewhere in the range of 93%. What makes aluminized mirrors appear to have a higher reflectance is the type of reflectance they exhibit - Specular Reflection - https://en.wikipedia.org/wiki/Specular_reflection Multi-layer dielectric mirrors, however, require expensive coatings in expensive vacuum chambers and would never be economically viable in large sizes and mass-produced. They also typically have a very narrow range of wavelengths that they can reflect that well. The paint that they are talking about here exhibits diffuse reflection. https://en.wikipedia.org/wiki/Diffuse_reflection


Since you seem to know so much about it, why did you not think of this earlier?

Eastman Kodak made a coating from Barium Sulfate long ago that was considered the "gold standard" for "white" https://www.labsphere.com/labsphere.../spectraflect/6080-white-reflectance-coating/

If TiO2 were capable of achieving the level of reflectance that they determined that Barium Sulfate can, they would have chosen that instead. They did, however, do months of research on this. How much research did you do?
It's just chemistry. Different crystalline structures of titanium can be bimodal or multimodal, instead of 'single' modal, these different crystal structures can be used to create different reflective indexes, like ultrafine TiO2 being mixed with ultrafine ZnO to make skin-sunscreen. This may also apply to paint-like coatings...and it might not. Barium (Baryta) isn't a free element, various forms of either one are used in similar types of applications. They seem similar, anyhow. A lot of carbonates are really kind of extra-white so there are probably many applications yet to be found, that said, 'new' brighter whiter paint from this already aged bright white pigment doesn't seem to be all that groundbreaking. Just saying, maybe it is groundbreaking. *shrug*

:rolleyes: I think it is interesting that most of the posters to this thread seem to think they have more knowledge and a better tack. These researchers have shown that they accomplished what they had set out to do - make a coating that would cool the surface under virtually any temperature conditions.

If they're so smart why is their white paint research on Techspot being mocked? /s
Thanks for the bit on reflectivity, didn't know about that! ✌
 

Farkinell

Posts: 138   +207
No inexpensive mirrors achieve reflectance as high as 98.1. Multi-layer dielectric mirrors, such as those found in lasers, are about the only ones that can achieve anywhere near that reflectance value. Some of those mirrors achieve even higher reflectance but, simple "aluminized" mirrors only achieve a reflectance value somewhere in the range of 93%. What makes aluminized mirrors appear to have a higher reflectance is the type of reflectance they exhibit - Specular Reflection - https://en.wikipedia.org/wiki/Specular_reflection Multi-layer dielectric mirrors, however, require expensive coatings in expensive vacuum chambers and would never be economically viable in large sizes and mass-produced. They also typically have a very narrow range of wavelengths that they can reflect that well. The paint that they are talking about here exhibits diffuse reflection. https://en.wikipedia.org/wiki/Diffuse_reflection


Since you seem to know so much about it, why did you not think of this earlier?

Eastman Kodak made a coating from Barium Sulfate long ago that was considered the "gold standard" for "white" https://www.labsphere.com/labsphere.../spectraflect/6080-white-reflectance-coating/

If TiO2 were capable of achieving the level of reflectance that they determined that Barium Sulfate can, they would have chosen that instead. They did, however, do months of research on this. How much research did you do?

An oddly defensive response, were you one of the researchers? No one is mocking their work, just commentating that it might not be as groundbreaking as it appears. As for how much research I have done, if I’m including my masters degree in chemistry then 4 years.