10 ms·

How white can white paint get?

77 points by mhb 4y ago

cobbaut 4y ago
And yet men will not be able to tell the difference. I have a flat with white painted walls, or so I thought... until a woman told me they were cream, milk and eggshell :-/
- themitigating 4y ago
  Maybe you can tell the difference but to express your masculinity pretend not to. Why? Because caring and beauty are feminine.
  - sircastor 4y ago
    Familiarity with these sorts of decorative details are often considered to a non-masculine trait. Though I suspect that most of the time it’s just that some people don’t care. And it’s possible that tracks with gender norms, but I think it’s probably that many men don’t feel like they’re allowed to care. A reminder that you’re allowed to care about whatever you want.
  - jwestbury 4y ago
    This is a complicated subject. Color perception is influenced by culture[0], so how someone is raised can impact their ability to discern color differences. It's quite possible that men in (Western|American) cultures are raised in such a way that their color perception is more limited than that of women despite no biological differences. Of course, there's plenty of research[1] showing women are better at color discrimination than men. 0. https://ec.europa.eu/research-and-innovation/en/horizon-magazine/how-we-perceive-colour-depends-our-culture-and-language-prof-anna-franklin https://ec.europa.eu/research-and-innovation/en/horizon-maga... 1. https://pubmed.ncbi.nlm.nih.gov/21675035/#:~:text=Color%20wise%20also%2C%20females%20gave,shades%20of%20colors%20than%20males https://pubmed.ncbi.nlm.nih.gov/21675035/#:~:text=Color%20wi....
    - phicoh 4y ago
      I wonder what the effect is of language. If on average men know only a few names of colors, then how can they remember or talk about the variations in between?
    - S_Bear 4y ago
      I started painting miniatures again a few years ago and my appreciation (and vocabulary) for colors has dramatically expanded, especially when I started mixing primaries from scratch. I literally see the world in a different, richer way. I wish I would have realized this sooner. Maybe gutting art programs in American public schools was a bad idea.
      - dekhn 4y ago
        I can second this: spend a lot of time working with subtle color variations (not just frequency, but the various matte/shiny bits). I learned I LOVE highly saturated colors. Recent car paint was also a revelation to me (https://www.blackbirdspyplane.com/p/why-do-new-cars-look-like-this https://www.blackbirdspyplane.com/p/why-do-new-cars-look-lik...).
  - rayiner 4y ago
    There is a biological difference in color perception, as well as hearing and smell: https://www.nbcnews.com/health/body-odd/men-women-really-do-see-world-differently-flna978565 https://www.nbcnews.com/health/body-odd/men-women-really-do-... > Abramov explained in a statement these elements of vision are linked to specific sets of thalamic neurons in the brain's primary visual cortex. The development of these neurons is controlled by male sex hormones called androgens when the embryo is developing into a fetus.
    - dekhn 4y ago
      here's the actual science paper, which is always less exciting than the public press. https://bsd.biomedcentral.com/articles/10.1186/2042-6410-3-21 https://bsd.biomedcentral.com/articles/10.1186/2042-6410-3-2...
  - kayodelycaon 4y ago
    So... everyone that works with graphic design is feminine?
  - msm_ 4y ago
    > Because caring and beauty are feminine. Is this something you (or people you're familiar with) believe? Never encountered this norm before.
    - yowzadave 4y ago
      I believe the comment was meant as an ironic dismissal of GP's assertion that men can't tell the difference between colors, but women can. As an architect, I can confirm that there are many men who know the difference between cream/milk/eggshell!
      - brookst 4y ago
        This is true, and we should be suspicious of gender stereotypes. But it is also true that on average men are worse at seeing color gradations, just because the incidence of color deficiency is 10x higher in men. So any particular man may see color as well as any particular woman, but if you had to pick one person at random to save the world in the galactic color identification game show, you’d best pick a woman.
- doikor 4y ago
  A lot of people have a terrible conception of what proper white is. Often what many think of as white is white mixed with blue. This is super evident after properly calibrating the white point of a (good) TV. Most casual viewers will say that the whites are now yellow/orange but in reality they are just used to always looking at white with a lot of blue mixed in. I've had similar experience with a interior designer friend of mine who told me my new white walls were not white but cream. I have a spectrophotometer that pretty clearly said that my walls were closer to white then his walls that he insisted were proper white (they were white mixed with blue)
  - sp332 4y ago
    Are you calibrating the TV to 5000k when they expect 6000k?
    - doikor 4y ago
      6500K is what one should be calibrating for. A TV straight from the shop in some cases is more like 7500 or 8000K or even more (well into the blue range) Most content is mastered for this 6500K as that is what the D65 standard is and the tv/film standards like Rec709 and Rec2020 use D65.
      - morcheeba 4y ago
        There are also cultural differences, too. Asian companies preferred colder whites, while our US customer wanted a warmer white. We were told this made the different skin tones more attractive.
  - jwestbury 4y ago
    > Often what many think of as white is white mixed with blue. This is super evident after properly calibrating the white point of a (good) TV. Most casual viewers will say that the whites are now yellow/orange but in reality they are just used to always looking at white with a lot of blue mixed in. "White" is tricky, because it's dependent on color temperature of the light which is illuminating the given surface. If someone is used to viewing white objects under daylight, but you're calibrating their TV to match the color temperature of their indoor environment (which proper calibration should do), then the "white" displayed on their TV will be a fundamentally different color from the "white" they see reflected off a white surface outside. This effect is going to be found to be doubly true if you're calibrating to indoor lighting in the evening, but they watch their TV at noon in the daylight with the windows open -- because the color temperature of the environment will now be much higher than the color temperature of the screen.
- wjnc 4y ago
  So we recently went from RAL 9010 to RAL 9016 for the walls (with colours and walls to create a nice atmosphere) and to my horror the difference between the RAL 9001 (cream) doors and frames is suddenly unbearable. This coming from a person who has a hard time naming the less than basic colours. Not to get me started on the millions of colours you paint your walls in. I did have a laugh when I found out that proprietary paint colours are a big thing, a few weeks after reading on HN about Adobe "cancelling" a colour. Proprietary colours are a thing I can suddenly talk about with repair guys. Car paints are proprietary. Kitchen panel paints are proprietary. It's a whole new world. It's not just RGB, there's gloss and sparkle to consider.
- jjulius 4y ago
  ... just men?
- dekhn 4y ago
  This seems like an unnecessary stereotype to state in a comment on Hacker News.
  - fwlr 4y ago
    So there’s these three sets of cells in the eye, each tuned to a different wavelength of light, and the difference in relative activations of each cell type in response to a given light is what provides color information. Which wavelength each set of cells is tuned to varies quite a bit person to person. If your wavelength “tunings” for two types of cells are too close together, then there’s less relative difference in their activation for any given wavelength of light, and thus - in the most rigorous information-theoretic sense - there is literally less color information available. We pick an arbitrary threshold of diminished color information and call that CVD, color vision deficiency. Depending on which threshold you pick for CVD, males are anywhere from 10 to 20 to 50 _times_ more likely to have it than females. Of course, this “has / does not have CVD” binary is an artifact of us picking a threshold; the real underlying mechanism is that the distribution of wavelength tunings in the male population is much more heavily weighted towards “overlapping”. Put another way, you have two overlapping bell curves of “how much color information can your eye cells theoretically generate” and if you drop a single point on that graph you can capture 1% of females and 10% of males to the left of it (for that 10x figure), or 0.02% of females and 1% of males to the left of the chosen point (for that 50x figure), or anywhere in between. And the fact that you can do this tells us the two bell curves very likely have different means and standard deviations. The search term is “spectral sensitivity” if you’re interested in finding out more. (I do know that “but it’s true” isn’t considered to be a good rebuttal to “it’s a stereotype”, but it kinda seems like it should be, and I don’t really know why it isn’t. Also, as someone with extreme CVD, color vision is just a fantastically interesting topic regardless of sex differences. The way those EnChroma glasses that “treat” color vision deficiency work is they block out a small section of the light wavelengths where CVD tends to have high overlap. This artificially increases the relative difference in activation, meaning the brain can extract more color data, with the practical result that people with CVD put on these glasses and see colors with an intensity they’ve never seen before. But it gets even cooler! For instance, did you know if we develop the technology to directly stimulate those different wavelength receptors independently of each other, we can make those receptors report “differences in relative activation” that are literally impossible to achieve with any combination of light wavelengths? That is, the cells will happily report perfectly well-formed color data to the brain, except that it’s data in a range that no brain has ever received before. The visual cortex seems like it does fairly general information processing, at least at the lower levels before we start tagging that information with e.g. emotional responses or linguistic names, so on some level our brain would probably be able to make immediate sense of this previously “out of band” information. It must be able to do so, or else CVD sufferers wouldn’t get such vivid reactions to EnChroma glasses. So it’s very plausible that this procedure would instantly unlock actual “new color experiences” for everyone. How cool is that?)
denton-scratch 4y ago
> cannot cool a surface below the ambient temperature. Only active cooling can cool anything below the ambient temperature. 100% reflectivity can prevent it absorbing more heat, if you can achieve it, but it doesn't cool anything down. > “Barium sulfate has reflective properties that allow us to hold below ambient temperature,” said Felicelli That's a bit more like it: 3/4 of the way down the page, someone finally points out that paint can't cool anything, it can only stop it warming up.
- jcims 4y ago
  >Only active cooling can cool anything below the ambient temperature. Not exactly: https://en.wikipedia.org/wiki/Radiative_cooling https://en.wikipedia.org/wiki/Radiative_cooling Couple of videos explaining the effect https://www.youtube.com/watch?v=N3bJnKmeNJY https://www.youtube.com/watch?v=N3bJnKmeNJY https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=5zW9_ztTiw8
- orev 4y ago
  An object in a room at ambient temperature would slowly warm up to equal the same temperature from the conduction of the warmer air around it. If the temperature of an object can “hold below ambient”, it means it must be able to allow the object to shed heat energy, at least at the same rate or faster than it absorbs the ambient heat. I.E. cooling.
- dahart 4y ago
  What’s the difference in practice, in summer weather? If the ambient temp is 30C in the morning and heats up to 40C in the afternoon, for example, then a paint that keeps things at 30 could replace active cooling on a red house with a brown roof whose surfaces exposed to the sun might even heat up to 50. It seems fair to call paint that effectively reflects the sun’s heat a “cooling” method, because it’s cooling relative to what you’d have otherwise, right?
- planede 4y ago
  > Only active cooling can cool anything below the ambient temperature. It's more complex than that. Through thermal radiation objects on the surface of Earth are also thermodynamically connected to the surface of the Sun (~6000K) and Space (~4K). The way to cool below ambient temperature with passive cooling is to isolate from the Sun, radiation from nearby objects and and conducting heat from surrounding air as much as possible, while making the thermal connection to Space as strong as possible. 1. How to isolate from the Sun: surface reflective in the spectrum where the thermal radiation from the Sun is the strongest, which is not too surprisingly the visible light spectrum (hence this article) 2. How to isolate from surrounding objects: insulation against conduction + surface reflective in the spectrum where the surrounding objects' thermal radiation is strongest (somewhere in infrared). 3. Thermal connection with space: you want to emit in the infrared spectrum as strong as possible. 2 and 3 are seemingly in contradiction, as a surface can't be a good reflector and good emitter at the same wavelength at the same time. But just have a geometry where the surface satisfying point 2 is pointed towards surrounding objects, while the surface satisfying point 3 radiates towards space.
olivierduval 4y ago
98,1% of the heat is reflected... to where ? It's nice to have a room "not too warm"... unless it's a lot warmer in the street and you cant go outside! Let's imagine a "totally white" town (white on walls, streets, roofs): the air will be quite hot, or am I misunderstanding something ? So it look to me that we will trade one problem (warm outside and inside) for another one (cooler inside and warmer outside)
- CorrectHorseBat 4y ago
  Heat mostly travels through air, air gets hot from being in contact with hot things. The heat will be reflected back to space.
- hammock 4y ago
  “The air” is big, and warming affects winds which move the air elsewhere. I would also mention the ground (very big, planet-sized) as a heat sink, but in cities where it’s all covered with concrete and pavement it does reflect a lot of heat back which is one reason why we observe cities hotter than the country otherwise would be
- dahart 4y ago
  What’s the problem with cooler inside and warmer outside? How much warmer outside do you suppose this white paint makes the outside?
- planede 4y ago
  In any case, it's better to keep the heat outside than letting it in then pump it out with an AC with some additional heat on top.
- roter 4y ago
  What you seek to do is increase the bulk albedo of the ground/surface/neighbourhood/city resulting in the net reflected solar radiation approaching the incoming leading to minimal absorbed shortwave and thus less compensating emitted longwave (sigma * T_surf*4). If you increase albedo, you're definitely going to lower the air temperature during the day. Rays are going to bounce around and eventually leave without warming anything. Other than your body if you haven't painted yourself white. However, with all these reflective surfaces you do get concerned with direct solar i.e. skiing in shorts & glare e.g. the "walkie-talkie" building [0]. [0] https://www.bbc.com/news/uk-england-london-23930675 https://www.bbc.com/news/uk-england-london-23930675
franciscop 4y ago
> The concept of using white paint to deflect heat isn’t new. As far back as the 1970s, scientists and manufacturers had been developing whiter and whiter paints In the Mediterranean (at least, probably many other areas) this has been done for thousands of years by painting the houses white to keep the heat out as much as possible, as well as a variety of other techniques like smart air management. So I think "as far as the 70s" is fairly misleading, it should be more like "for thousands of years...".
- fractallyte 4y ago
  ...and the 'paint' is made using basic ingredients: https://en.wikipedia.org/wiki/Whitewash https://en.wikipedia.org/wiki/Whitewash Easy to apply, long-lasting, biodegradable, and (from the linked article) it "produces a unique surface glow due to the double refraction of calcite crystals."
  - franciscop 4y ago
    NEW RELEASE: bio natural organic paint made from seashells to cool down your house 2023 release innovation startup Mediterraneans: get out of here Edit: how to make lime/limestone in a low-tech way from Primitive Technology: https://www.youtube.com/watch?v=Ek3aeUhHaFY https://www.youtube.com/watch?v=Ek3aeUhHaFY
  - aidenn0 4y ago
    And it's so fun to apply that people will pay to do it for you!
- dmitriid 4y ago
  > So I think "as far as the 70s" is fairly misleading As far as the 70s refers to efforts to create whiter and more reflective paint.
  - deleted 4y ago
    [deleted]
  - nomel 4y ago
A_D_E_P_T 4y ago
What's especially interesting is that the coloring agent they hit upon -- hexagonal boron nitride -- is structurally analogous to graphite. Graphite and its compounds are important black dyes. To go a step further: Vantablack, like most other carbon nanostructures, is functionally graphitic (sp2 bonding). And it's the blackest pigment known. I wonder if the boundaries of hBN can be pushed in the same manner. Perhaps hBN nanostructures can make for even whiter pigments? It'll be interesting to find out. As an aside, I had once heard that beryllium oxide is the whitest known pigment, but it's so rare and toxic that it can never leave the lab under any reasonable circumstances.
- inkcapmushroom 4y ago
  >I had once heard that beryllium oxide is the whitest known pigment, but it's so rare and toxic Don't let industry know about it, they'll be putting it in our toothpaste!
DeathArrow 4y ago
[flagged]
college_physics 4y ago
> As far back as the 1970s, scientists and manufacturers had been developing whiter and whiter paints to help reflect sunlight and keep buildings and other surfaces cool The thing I am pondering: if the objective is to reflect as much as possible sunlight shouldn't the solution be more like a... mirror than a white paint? According to wikipedia a very complex dielectric mirror can reflect up to 99.999% of the light incident upon it while simple mirrors may reflect 99.9% of the light. Cost and practicality will significantly lower these figures but there is still a gap versus the current 98.1% white paint record. I recall seeing various gold tinted mirrors covering buildings but they seem out of fashion.
- carlmr 4y ago
  Specular reflections will blind pilots, drivers and even pedestrians, melt things if the mirrors aren't completely planar, and cause all kinds of issues.
  - college_physics 4y ago
    you could reduce that by making the surface locally rough or having random geometric segments - whatever is easier to manufacture. Since this is not a mirror that must preserve image integrity anything goes.
    - awestroke 4y ago
      Sounds like you're pitching white paint
      - college_physics 4y ago
        ha ha, size (of your reflectors) matters
    - ominous_prime 4y ago
      You literally described diffuse reflection, which is "white paint"
OscarCunningham 4y ago
Would this actually look like bright white paint? Maybe because they're also trying to reflect light outside the visible spectrum it might not be as bright in the colours we can actually see.
mhb 4y ago
There is also two part IR reflective paint. With an IR reflecting bottom layer and a colored top layer. Doesn't say what percentage IR is reflected though: https://www.newscientist.com/article/2241717-infrared-reflecting-paint-can-cool-buildings-even-when-it-is-black/ https://www.newscientist.com/article/2241717-infrared-reflec...
nunodonato 4y ago
Got me wondering, how viable would it be to paint your house white in the summer and with a darker color in the winter? From a cost perspective (paint cost+work vs heat/cooling savings). And how much does it matter if you have good insulation in the walls? is the paint still relevant?
- awestroke 4y ago
  Painting is labor intensive
  - albert_e 4y ago
    e-ink roofs :) press a button to turn the walls from black to white :)
    - dylan604 4y ago
      "Down the road, Ruan said, he’s also interested in creating reflective paint in different colors, as well as paints that could switch from reflective to absorptive, depending on the season—like a building-size version of drinkware that changes color when you pour hot or cold water into it." From the TFA
- bombcar 4y ago
  The "normal" way this is done is with trees. During the summer, they have lots of leaves and shade the house (especially if you have them in the right place for the summer sun) and in the winter the leaves fall off and the winter sun can shine through. But insulation matters much more in the winter; the color/shade only reduces the energy load, it doesn't dissipate it.
  - nunodonato 4y ago
    yes, its ridiculous how in my country people can't plant trees to close to houses due to the summer fires
erybodyknows 4y ago
This reminds me of the blackest acrylic paint from Stuart Semple. https://culturehustle.com/products/black-3-0-the-worlds-blackest-black-acrylic-paint-150ml https://culturehustle.com/products/black-3-0-the-worlds-blac...
- S_Bear 4y ago
  Stuart Semple also has a 'white 2.0' that looks like neon white compared to regular white. https://www.culturehustleusa.com/products/white-20 https://www.culturehustleusa.com/products/white-20
  - Pet_Ant 4y ago
    If you want an idea of how this might feel on a room scale, here are Action Lab's whitest & blackest rooms: Whitest: https://www.youtube.com/watch?v=DjdFn1RYHDE https://www.youtube.com/watch?v=DjdFn1RYHDE Blackest: https://www.youtube.com/watch?v=p6q54q2iam8 https://www.youtube.com/watch?v=p6q54q2iam8
- nicd 4y ago
  I understand Musou black has it beat: https://takemy.money/musou-black-the-new-blackest-paint-in-the-world#:~:text=That%20said%2C%20Musou%20Black%20is,Semple's%20next%20move%20will%20be https://takemy.money/musou-black-the-new-blackest-paint-in-t...! And the blackest (non-acrylic) paint is Vantablack, the carbon-nanotube-based paint that is infamously only available to Anish Kapoor.
yellow_lead 4y ago
> Eventually, Ruan’s team came up with a paint that used high concentrations of barium sulfate particles of varying sizes, which was able to reflect 95% of sunlight. This substance is also used as a radiographic contrast agent and turns your poop white.
lkbm 4y ago
> The paint is also being perfected and tested to ensure it can resist dirt and can last as long under UV light as commercial white paints. Having stored some old closet doors on the porch near a small urban road for a few months, this was my first thought. The grime that accumulated from exhaust was incredible. (There were leaf blowers running across the way a couple times a week, so I'm guessing those were the main culprit.) Things turn dingy in the city remarkably fast. Cleaner cars and elimination of two-stroke engines will help, but for now I think that for most exterior uses, "resists smog" will be more important than "starts out very white" unless you clean it frequently and thoroughly.
- bombcar 4y ago
  A surprising amount of that "grime" is rubber dust from tires. The exhaust helps in getting the items a bit "sticky" and then dust and dirt clings much easier to it.
wppick 4y ago
I once bought a paint so white it thought sliced bread was too spicy
Syzygies 4y ago
Two decades ago I painted my apartment with artist grade titanium white acrylic. It still looks new. A temperament that I share with everyone on HN is a suspicion of convention. So many common practices are dumb that it's hard to see each one coming in advance. One is always on edge waiting for the next shoe to drop. I'm supposed to spend days clearing my apartment, so the bottom rung of the construction trades can come in using paint that only lasts four years, dabbing hanging peels back in place with their brushes? Why did I actually have to go through this once to see this is the poster child for "stupid"? I've also never understood the fashion choice of "off white". Titanium white is brighter, a better lit room day or night. It can become a color mirror, where a corner looks red because a red object is nearby. For anyone tempted to try this, the student grades have less pigment, and the most expensive brands have the most pigment. It would also appear in an art supply store that there's only one kind of primer, and mediums vary only by gloss. Going to the manufacturer's sites, there are variations intended to survive the outside wall of a building. One could probably wind up someone on a phone call, and get excellent advice on which products to use. On the other hand, I used what I found at Pearl Paint in NYC, and it held up fine.
- Syzygies 4y ago
  Once I recognized that art supplies can substitute for construction materials, this opened up a world for me. For example, though miscommunication I had many holes to fill in some period kitchen cabinet doors in my house. The normal sequence would be filler, primer, cabinet paint. Instead I played with stiff acrylic modeling compound. I got the paint store to give me a sample of what they squirt into the paint, and I played around with the pigment and different mediums until the color and gloss was an exact match. Now I could fill each hole in one pass, no painting, and no one could find the hole afterwards.
- JohnFen 4y ago
  > I've also never understood the fashion choice of "off white". Personally, if it's a room I'm going to be relaxing in (bedroom, living room, etc.) as opposed to a work room, I strongly prefer an off-white over a bright white. It's more muted and relaxing.
deleted 4y ago
[deleted]
ryzvonusef 4y ago
for people who want to watch a video on white paint and cooling: https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=dNs_kNilSjk https://www.youtube.com/watch?v=dNs_kNilSjk

77 points by mhb 4y ago

And yet men will not be able to tell the difference. I have a flat with white painted walls, or so I thought... until a woman told me they were cream, milk and eggshell :-/

themitigating 4y ago
Maybe you can tell the difference but to express your masculinity pretend not to. Why? Because caring and beauty are feminine.
- sircastor 4y ago
  Familiarity with these sorts of decorative details are often considered to a non-masculine trait. Though I suspect that most of the time it’s just that some people don’t care. And it’s possible that tracks with gender norms, but I think it’s probably that many men don’t feel like they’re allowed to care. A reminder that you’re allowed to care about whatever you want.
- jwestbury 4y ago
  This is a complicated subject. Color perception is influenced by culture[0], so how someone is raised can impact their ability to discern color differences. It's quite possible that men in (Western|American) cultures are raised in such a way that their color perception is more limited than that of women despite no biological differences. Of course, there's plenty of research[1] showing women are better at color discrimination than men. 0. https://ec.europa.eu/research-and-innovation/en/horizon-magazine/how-we-perceive-colour-depends-our-culture-and-language-prof-anna-franklin https://ec.europa.eu/research-and-innovation/en/horizon-maga... 1. https://pubmed.ncbi.nlm.nih.gov/21675035/#:~:text=Color%20wise%20also%2C%20females%20gave,shades%20of%20colors%20than%20males https://pubmed.ncbi.nlm.nih.gov/21675035/#:~:text=Color%20wi....
  - phicoh 4y ago
    I wonder what the effect is of language. If on average men know only a few names of colors, then how can they remember or talk about the variations in between?
  - S_Bear 4y ago
    I started painting miniatures again a few years ago and my appreciation (and vocabulary) for colors has dramatically expanded, especially when I started mixing primaries from scratch. I literally see the world in a different, richer way. I wish I would have realized this sooner. Maybe gutting art programs in American public schools was a bad idea.
    - dekhn 4y ago
      I can second this: spend a lot of time working with subtle color variations (not just frequency, but the various matte/shiny bits). I learned I LOVE highly saturated colors. Recent car paint was also a revelation to me (https://www.blackbirdspyplane.com/p/why-do-new-cars-look-like-this https://www.blackbirdspyplane.com/p/why-do-new-cars-look-lik...).
- rayiner 4y ago
  There is a biological difference in color perception, as well as hearing and smell: https://www.nbcnews.com/health/body-odd/men-women-really-do-see-world-differently-flna978565 https://www.nbcnews.com/health/body-odd/men-women-really-do-... > Abramov explained in a statement these elements of vision are linked to specific sets of thalamic neurons in the brain's primary visual cortex. The development of these neurons is controlled by male sex hormones called androgens when the embryo is developing into a fetus.
  - dekhn 4y ago
    here's the actual science paper, which is always less exciting than the public press. https://bsd.biomedcentral.com/articles/10.1186/2042-6410-3-21 https://bsd.biomedcentral.com/articles/10.1186/2042-6410-3-2...
- kayodelycaon 4y ago
  So... everyone that works with graphic design is feminine?
- msm_ 4y ago
  > Because caring and beauty are feminine. Is this something you (or people you're familiar with) believe? Never encountered this norm before.
  - yowzadave 4y ago
    I believe the comment was meant as an ironic dismissal of GP's assertion that men can't tell the difference between colors, but women can. As an architect, I can confirm that there are many men who know the difference between cream/milk/eggshell!
    - brookst 4y ago
      This is true, and we should be suspicious of gender stereotypes. But it is also true that on average men are worse at seeing color gradations, just because the incidence of color deficiency is 10x higher in men. So any particular man may see color as well as any particular woman, but if you had to pick one person at random to save the world in the galactic color identification game show, you’d best pick a woman.
doikor 4y ago
A lot of people have a terrible conception of what proper white is. Often what many think of as white is white mixed with blue. This is super evident after properly calibrating the white point of a (good) TV. Most casual viewers will say that the whites are now yellow/orange but in reality they are just used to always looking at white with a lot of blue mixed in. I've had similar experience with a interior designer friend of mine who told me my new white walls were not white but cream. I have a spectrophotometer that pretty clearly said that my walls were closer to white then his walls that he insisted were proper white (they were white mixed with blue)
- sp332 4y ago
  Are you calibrating the TV to 5000k when they expect 6000k?
  - doikor 4y ago
    6500K is what one should be calibrating for. A TV straight from the shop in some cases is more like 7500 or 8000K or even more (well into the blue range) Most content is mastered for this 6500K as that is what the D65 standard is and the tv/film standards like Rec709 and Rec2020 use D65.
    - morcheeba 4y ago
      There are also cultural differences, too. Asian companies preferred colder whites, while our US customer wanted a warmer white. We were told this made the different skin tones more attractive.
- jwestbury 4y ago
  > Often what many think of as white is white mixed with blue. This is super evident after properly calibrating the white point of a (good) TV. Most casual viewers will say that the whites are now yellow/orange but in reality they are just used to always looking at white with a lot of blue mixed in. "White" is tricky, because it's dependent on color temperature of the light which is illuminating the given surface. If someone is used to viewing white objects under daylight, but you're calibrating their TV to match the color temperature of their indoor environment (which proper calibration should do), then the "white" displayed on their TV will be a fundamentally different color from the "white" they see reflected off a white surface outside. This effect is going to be found to be doubly true if you're calibrating to indoor lighting in the evening, but they watch their TV at noon in the daylight with the windows open -- because the color temperature of the environment will now be much higher than the color temperature of the screen.
wjnc 4y ago
So we recently went from RAL 9010 to RAL 9016 for the walls (with colours and walls to create a nice atmosphere) and to my horror the difference between the RAL 9001 (cream) doors and frames is suddenly unbearable. This coming from a person who has a hard time naming the less than basic colours. Not to get me started on the millions of colours you paint your walls in. I did have a laugh when I found out that proprietary paint colours are a big thing, a few weeks after reading on HN about Adobe "cancelling" a colour. Proprietary colours are a thing I can suddenly talk about with repair guys. Car paints are proprietary. Kitchen panel paints are proprietary. It's a whole new world. It's not just RGB, there's gloss and sparkle to consider.
jjulius 4y ago
... just men?
dekhn 4y ago
This seems like an unnecessary stereotype to state in a comment on Hacker News.
- fwlr 4y ago
  So there’s these three sets of cells in the eye, each tuned to a different wavelength of light, and the difference in relative activations of each cell type in response to a given light is what provides color information. Which wavelength each set of cells is tuned to varies quite a bit person to person. If your wavelength “tunings” for two types of cells are too close together, then there’s less relative difference in their activation for any given wavelength of light, and thus - in the most rigorous information-theoretic sense - there is literally less color information available. We pick an arbitrary threshold of diminished color information and call that CVD, color vision deficiency. Depending on which threshold you pick for CVD, males are anywhere from 10 to 20 to 50 _times_ more likely to have it than females. Of course, this “has / does not have CVD” binary is an artifact of us picking a threshold; the real underlying mechanism is that the distribution of wavelength tunings in the male population is much more heavily weighted towards “overlapping”. Put another way, you have two overlapping bell curves of “how much color information can your eye cells theoretically generate” and if you drop a single point on that graph you can capture 1% of females and 10% of males to the left of it (for that 10x figure), or 0.02% of females and 1% of males to the left of the chosen point (for that 50x figure), or anywhere in between. And the fact that you can do this tells us the two bell curves very likely have different means and standard deviations. The search term is “spectral sensitivity” if you’re interested in finding out more. (I do know that “but it’s true” isn’t considered to be a good rebuttal to “it’s a stereotype”, but it kinda seems like it should be, and I don’t really know why it isn’t. Also, as someone with extreme CVD, color vision is just a fantastically interesting topic regardless of sex differences. The way those EnChroma glasses that “treat” color vision deficiency work is they block out a small section of the light wavelengths where CVD tends to have high overlap. This artificially increases the relative difference in activation, meaning the brain can extract more color data, with the practical result that people with CVD put on these glasses and see colors with an intensity they’ve never seen before. But it gets even cooler! For instance, did you know if we develop the technology to directly stimulate those different wavelength receptors independently of each other, we can make those receptors report “differences in relative activation” that are literally impossible to achieve with any combination of light wavelengths? That is, the cells will happily report perfectly well-formed color data to the brain, except that it’s data in a range that no brain has ever received before. The visual cortex seems like it does fairly general information processing, at least at the lower levels before we start tagging that information with e.g. emotional responses or linguistic names, so on some level our brain would probably be able to make immediate sense of this previously “out of band” information. It must be able to do so, or else CVD sufferers wouldn’t get such vivid reactions to EnChroma glasses. So it’s very plausible that this procedure would instantly unlock actual “new color experiences” for everyone. How cool is that?)

denton-scratch 4y ago

> cannot cool a surface below the ambient temperature. Only active cooling can cool anything below the ambient temperature. 100% reflectivity can prevent it absorbing more heat, if you can achieve it, but it doesn't cool anything down. > “Barium sulfate has reflective properties that allow us to hold below ambient temperature,” said Felicelli That's a bit more like it: 3/4 of the way down the page, someone finally points out that paint can't cool anything, it can only stop it warming up.

jcims 4y ago
>Only active cooling can cool anything below the ambient temperature. Not exactly: https://en.wikipedia.org/wiki/Radiative_cooling https://en.wikipedia.org/wiki/Radiative_cooling Couple of videos explaining the effect https://www.youtube.com/watch?v=N3bJnKmeNJY https://www.youtube.com/watch?v=N3bJnKmeNJY https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=5zW9_ztTiw8
orev 4y ago
An object in a room at ambient temperature would slowly warm up to equal the same temperature from the conduction of the warmer air around it. If the temperature of an object can “hold below ambient”, it means it must be able to allow the object to shed heat energy, at least at the same rate or faster than it absorbs the ambient heat. I.E. cooling.
dahart 4y ago
What’s the difference in practice, in summer weather? If the ambient temp is 30C in the morning and heats up to 40C in the afternoon, for example, then a paint that keeps things at 30 could replace active cooling on a red house with a brown roof whose surfaces exposed to the sun might even heat up to 50. It seems fair to call paint that effectively reflects the sun’s heat a “cooling” method, because it’s cooling relative to what you’d have otherwise, right?
planede 4y ago
> Only active cooling can cool anything below the ambient temperature. It's more complex than that. Through thermal radiation objects on the surface of Earth are also thermodynamically connected to the surface of the Sun (~6000K) and Space (~4K). The way to cool below ambient temperature with passive cooling is to isolate from the Sun, radiation from nearby objects and and conducting heat from surrounding air as much as possible, while making the thermal connection to Space as strong as possible. 1. How to isolate from the Sun: surface reflective in the spectrum where the thermal radiation from the Sun is the strongest, which is not too surprisingly the visible light spectrum (hence this article) 2. How to isolate from surrounding objects: insulation against conduction + surface reflective in the spectrum where the surrounding objects' thermal radiation is strongest (somewhere in infrared). 3. Thermal connection with space: you want to emit in the infrared spectrum as strong as possible. 2 and 3 are seemingly in contradiction, as a surface can't be a good reflector and good emitter at the same wavelength at the same time. But just have a geometry where the surface satisfying point 2 is pointed towards surrounding objects, while the surface satisfying point 3 radiates towards space.

olivierduval 4y ago

98,1% of the heat is reflected... to where ? It's nice to have a room "not too warm"... unless it's a lot warmer in the street and you cant go outside! Let's imagine a "totally white" town (white on walls, streets, roofs): the air will be quite hot, or am I misunderstanding something ? So it look to me that we will trade one problem (warm outside and inside) for another one (cooler inside and warmer outside)

CorrectHorseBat 4y ago
Heat mostly travels through air, air gets hot from being in contact with hot things. The heat will be reflected back to space.
hammock 4y ago
“The air” is big, and warming affects winds which move the air elsewhere. I would also mention the ground (very big, planet-sized) as a heat sink, but in cities where it’s all covered with concrete and pavement it does reflect a lot of heat back which is one reason why we observe cities hotter than the country otherwise would be
dahart 4y ago
What’s the problem with cooler inside and warmer outside? How much warmer outside do you suppose this white paint makes the outside?
planede 4y ago
In any case, it's better to keep the heat outside than letting it in then pump it out with an AC with some additional heat on top.
roter 4y ago
What you seek to do is increase the bulk albedo of the ground/surface/neighbourhood/city resulting in the net reflected solar radiation approaching the incoming leading to minimal absorbed shortwave and thus less compensating emitted longwave (sigma * T_surf*4). If you increase albedo, you're definitely going to lower the air temperature during the day. Rays are going to bounce around and eventually leave without warming anything. Other than your body if you haven't painted yourself white. However, with all these reflective surfaces you do get concerned with direct solar i.e. skiing in shorts & glare e.g. the "walkie-talkie" building [0]. [0] https://www.bbc.com/news/uk-england-london-23930675 https://www.bbc.com/news/uk-england-london-23930675

franciscop 4y ago

> The concept of using white paint to deflect heat isn’t new. As far back as the 1970s, scientists and manufacturers had been developing whiter and whiter paints In the Mediterranean (at least, probably many other areas) this has been done for thousands of years by painting the houses white to keep the heat out as much as possible, as well as a variety of other techniques like smart air management. So I think "as far as the 70s" is fairly misleading, it should be more like "for thousands of years...".

fractallyte 4y ago
...and the 'paint' is made using basic ingredients: https://en.wikipedia.org/wiki/Whitewash https://en.wikipedia.org/wiki/Whitewash Easy to apply, long-lasting, biodegradable, and (from the linked article) it "produces a unique surface glow due to the double refraction of calcite crystals."
- franciscop 4y ago
  NEW RELEASE: bio natural organic paint made from seashells to cool down your house 2023 release innovation startup Mediterraneans: get out of here Edit: how to make lime/limestone in a low-tech way from Primitive Technology: https://www.youtube.com/watch?v=Ek3aeUhHaFY https://www.youtube.com/watch?v=Ek3aeUhHaFY
- aidenn0 4y ago
  And it's so fun to apply that people will pay to do it for you!
dmitriid 4y ago
> So I think "as far as the 70s" is fairly misleading As far as the 70s refers to efforts to create whiter and more reflective paint.
- deleted 4y ago
  [deleted]
- nomel 4y ago

A_D_E_P_T 4y ago

What's especially interesting is that the coloring agent they hit upon -- hexagonal boron nitride -- is structurally analogous to graphite. Graphite and its compounds are important black dyes. To go a step further: Vantablack, like most other carbon nanostructures, is functionally graphitic (sp2 bonding). And it's the blackest pigment known. I wonder if the boundaries of hBN can be pushed in the same manner. Perhaps hBN nanostructures can make for even whiter pigments? It'll be interesting to find out. As an aside, I had once heard that beryllium oxide is the whitest known pigment, but it's so rare and toxic that it can never leave the lab under any reasonable circumstances.

inkcapmushroom 4y ago
>I had once heard that beryllium oxide is the whitest known pigment, but it's so rare and toxic Don't let industry know about it, they'll be putting it in our toothpaste!

DeathArrow 4y ago

[flagged]

college_physics 4y ago

> As far back as the 1970s, scientists and manufacturers had been developing whiter and whiter paints to help reflect sunlight and keep buildings and other surfaces cool The thing I am pondering: if the objective is to reflect as much as possible sunlight shouldn't the solution be more like a... mirror than a white paint? According to wikipedia a very complex dielectric mirror can reflect up to 99.999% of the light incident upon it while simple mirrors may reflect 99.9% of the light. Cost and practicality will significantly lower these figures but there is still a gap versus the current 98.1% white paint record. I recall seeing various gold tinted mirrors covering buildings but they seem out of fashion.

carlmr 4y ago
Specular reflections will blind pilots, drivers and even pedestrians, melt things if the mirrors aren't completely planar, and cause all kinds of issues.
- college_physics 4y ago
  you could reduce that by making the surface locally rough or having random geometric segments - whatever is easier to manufacture. Since this is not a mirror that must preserve image integrity anything goes.
  - awestroke 4y ago
    Sounds like you're pitching white paint
    - college_physics 4y ago
      ha ha, size (of your reflectors) matters
  - ominous_prime 4y ago
    You literally described diffuse reflection, which is "white paint"

OscarCunningham 4y ago

Would this actually look like bright white paint? Maybe because they're also trying to reflect light outside the visible spectrum it might not be as bright in the colours we can actually see.

mhb 4y ago

There is also two part IR reflective paint. With an IR reflecting bottom layer and a colored top layer. Doesn't say what percentage IR is reflected though: https://www.newscientist.com/article/2241717-infrared-reflecting-paint-can-cool-buildings-even-when-it-is-black/ https://www.newscientist.com/article/2241717-infrared-reflec...

nunodonato 4y ago

Got me wondering, how viable would it be to paint your house white in the summer and with a darker color in the winter? From a cost perspective (paint cost+work vs heat/cooling savings). And how much does it matter if you have good insulation in the walls? is the paint still relevant?

awestroke 4y ago
Painting is labor intensive
- albert_e 4y ago
  e-ink roofs :) press a button to turn the walls from black to white :)
  - dylan604 4y ago
    "Down the road, Ruan said, he’s also interested in creating reflective paint in different colors, as well as paints that could switch from reflective to absorptive, depending on the season—like a building-size version of drinkware that changes color when you pour hot or cold water into it." From the TFA
bombcar 4y ago
The "normal" way this is done is with trees. During the summer, they have lots of leaves and shade the house (especially if you have them in the right place for the summer sun) and in the winter the leaves fall off and the winter sun can shine through. But insulation matters much more in the winter; the color/shade only reduces the energy load, it doesn't dissipate it.
- nunodonato 4y ago
  yes, its ridiculous how in my country people can't plant trees to close to houses due to the summer fires

erybodyknows 4y ago

This reminds me of the blackest acrylic paint from Stuart Semple. https://culturehustle.com/products/black-3-0-the-worlds-blackest-black-acrylic-paint-150ml https://culturehustle.com/products/black-3-0-the-worlds-blac...

S_Bear 4y ago
Stuart Semple also has a 'white 2.0' that looks like neon white compared to regular white. https://www.culturehustleusa.com/products/white-20 https://www.culturehustleusa.com/products/white-20
- Pet_Ant 4y ago
  If you want an idea of how this might feel on a room scale, here are Action Lab's whitest & blackest rooms: Whitest: https://www.youtube.com/watch?v=DjdFn1RYHDE https://www.youtube.com/watch?v=DjdFn1RYHDE Blackest: https://www.youtube.com/watch?v=p6q54q2iam8 https://www.youtube.com/watch?v=p6q54q2iam8
nicd 4y ago
I understand Musou black has it beat: https://takemy.money/musou-black-the-new-blackest-paint-in-the-world#:~:text=That%20said%2C%20Musou%20Black%20is,Semple's%20next%20move%20will%20be https://takemy.money/musou-black-the-new-blackest-paint-in-t...! And the blackest (non-acrylic) paint is Vantablack, the carbon-nanotube-based paint that is infamously only available to Anish Kapoor.

yellow_lead 4y ago

> Eventually, Ruan’s team came up with a paint that used high concentrations of barium sulfate particles of varying sizes, which was able to reflect 95% of sunlight. This substance is also used as a radiographic contrast agent and turns your poop white.

lkbm 4y ago

> The paint is also being perfected and tested to ensure it can resist dirt and can last as long under UV light as commercial white paints. Having stored some old closet doors on the porch near a small urban road for a few months, this was my first thought. The grime that accumulated from exhaust was incredible. (There were leaf blowers running across the way a couple times a week, so I'm guessing those were the main culprit.) Things turn dingy in the city remarkably fast. Cleaner cars and elimination of two-stroke engines will help, but for now I think that for most exterior uses, "resists smog" will be more important than "starts out very white" unless you clean it frequently and thoroughly.

bombcar 4y ago
A surprising amount of that "grime" is rubber dust from tires. The exhaust helps in getting the items a bit "sticky" and then dust and dirt clings much easier to it.

wppick 4y ago

I once bought a paint so white it thought sliced bread was too spicy

Syzygies 4y ago

Two decades ago I painted my apartment with artist grade titanium white acrylic. It still looks new. A temperament that I share with everyone on HN is a suspicion of convention. So many common practices are dumb that it's hard to see each one coming in advance. One is always on edge waiting for the next shoe to drop. I'm supposed to spend days clearing my apartment, so the bottom rung of the construction trades can come in using paint that only lasts four years, dabbing hanging peels back in place with their brushes? Why did I actually have to go through this once to see this is the poster child for "stupid"? I've also never understood the fashion choice of "off white". Titanium white is brighter, a better lit room day or night. It can become a color mirror, where a corner looks red because a red object is nearby. For anyone tempted to try this, the student grades have less pigment, and the most expensive brands have the most pigment. It would also appear in an art supply store that there's only one kind of primer, and mediums vary only by gloss. Going to the manufacturer's sites, there are variations intended to survive the outside wall of a building. One could probably wind up someone on a phone call, and get excellent advice on which products to use. On the other hand, I used what I found at Pearl Paint in NYC, and it held up fine.

Syzygies 4y ago
Once I recognized that art supplies can substitute for construction materials, this opened up a world for me. For example, though miscommunication I had many holes to fill in some period kitchen cabinet doors in my house. The normal sequence would be filler, primer, cabinet paint. Instead I played with stiff acrylic modeling compound. I got the paint store to give me a sample of what they squirt into the paint, and I played around with the pigment and different mediums until the color and gloss was an exact match. Now I could fill each hole in one pass, no painting, and no one could find the hole afterwards.
JohnFen 4y ago
> I've also never understood the fashion choice of "off white". Personally, if it's a room I'm going to be relaxing in (bedroom, living room, etc.) as opposed to a work room, I strongly prefer an off-white over a bright white. It's more muted and relaxing.

deleted 4y ago

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ryzvonusef 4y ago

for people who want to watch a video on white paint and cooling: https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=dNs_kNilSjk https://www.youtube.com/watch?v=dNs_kNilSjk