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Product Guide

New Paint Technologies

From air cleaning to energy generation to cooling, the possible future of paint is beyond anything we have known to date

In Europe, light-activated catalysts that neutralize airborne pollutants are embedded in paint to mop up air pollution. Image credit: AM Technology

Lately, developments in climate mitigation have often come from the labs of paint manufacturers. From high-tech coatings that scrub the air to coatings that will clean themselves or produce solar power, soon you’ll use your roller to do more than add color. Here’s a primer on recent developments in high-tech paint.

Air-cleaning paint

Air pollution remains a vexing health hazard difficult to control. Chemicals from vehicle exhaust and other commercial sources fill the lungs and leach into our bloodstream, causing illness. Enter Airlite paint of Milan, Italy. This manufacturer developed a coating that purifies air by neutralizing contaminates through a photochemical reaction. The company explains that their product generates a “concentration of electrons” that interact with oxygen and airborne water vapor. These electrons generate negative ions that attach to common pollutants. The negative charge causes the particles of pollutants to cling to positively charged surfaces such as walls coated with Airlite paint.

The company tested their material inside the Umberto Tunnel in Rome. This passageway offers a shortcut from the beautiful Piazza di Spagna to Via Nazionale. Built to alleviate traffic, the tunnel soon became one of the most polluted places in the capital. In a demonstration, Airlite coated the tunnel about ten years ago. The company says the tunnel is still white (clean), without any maintenance, and tests by La Sapienza University of Rome have shown a reduction of pollutants inside the tunnel approaching 51%.

Closer to home, manufacturers have developed coatings that promise to purify household air. Sherwin Williams’s SuperPaint comes with an air-purifying technology that, the company says, contributes to better indoor air quality by reducing volatile organic compound (VOC) levels from potential sources like carpet, cabinets, and fabrics. I looked and looked but could not find an explanation on how the paint sequesters or neutralizes…

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7 Comments

  1. Charlie Sullivan | | #1

    The description of the ultra-white paint is technically incorrect. The emission of thermal IR (far IR) is not a reflection process. It is thermal emission, the same process by which a person standing near a hot wood stove is warmed by radiation coming off that surface, but working with lower temperatures. The paint is radiating to the sky because the sky is colder than it is. This is the same phenomenon that was mischaracterized by the same author in another recent article.

  2. Fernando Pages | | #2

    Dear Charlie, the point of the article is to say many exciting, new developments are coming with paint. The specific sentence you refer to says, "It reflects 98% of solar radiation while outputting (reflecting) heat-generating infrared rays." I admit this statement is not clear. The reflection of infrared rays prevents the painted surface from absorbing this frequency and heating up. People understand reflection and not so easily the word emittance. Writers try to use simple language for understanding, even if technically inaccurate. I don’t pretend to write scientific papers. But following up on your comments on the article about solar cooling, I wrote to the developers of the product described in the article asking them to respond to your observations. Unfortunately, they did not reply to my email or call. I tried. Here too, I just wrote to Dr. Ruan, developer of the super-white paint, asking about the sentence you critique. If he replies, I will post his comments. Your observations are always welcome, and if I can respond with good information, I always will. In this case, the Purdue University press release about the paint says it “repels infrared heat from a surface and reflects up to 98.1% of sunlight.” Repel or reflect? To the layman – like me – this is a very subtle distinction.

    1. Charlie Sullivan | | #3

      Thanks for your reply. The more detailed sentence from the press release (https://www.purdue.edu/newsroom/releases/2021/Q3/purdue-record-for-the-whitest-paint-appears-in-latest-edition-of-guinness-world-records.html) says,

      "The formulation that Ruan’s lab created reflects 98.1% of solar radiation at the same time as emitting infrared heat. Because the paint absorbs less heat from the sun than it emits, a surface coated with this paint is cooled below the surrounding temperature without consuming power."

      That describes two things: 1. Reflecting solar radiation, and 2. emitting infrared heat. I think you might be misunderstanding that as talking about 1. reflecting visible sunlight and 2. reflecting infrared energy from the sun. In fact the 98.1% of solar radiation that it reflects includes the visible and IR light from the sun. Number 2 is a different phenomenon. Stopping incoming solar radiation, whether it's by reflecting it, repelling it, or locating the house in the shade of a big oak tree, can never cool a surface below ambient. That's why that second process is necessary to achieve cooing below the ambient temperature. It's OK if you don't understand that second process and can't describe it in technical detail, but it's a mistake to describe it as part of the first feature--the reflection of solar radiation.

      I'm not finding the "repel" language in the Purdue Press Release. Perhaps you have a different version?

      If you want help understanding heat transfer as you prepare any future articles, feel free to contact me. Kiley has my email.

      1. Fernando Pages | | #4

        I'd be happy to, Charlie. I try to get the technical stuff right -- although physics requires a level of education I d don't have. I appreciate the help and will take you up on it.

        1. Charlie Sullivan | | #5

          Looking forward to it!

  3. Fernando Pages | | #6

    Purdue University has a podcast on the development of ultra-white paint that offers an in-depth description of how the paint works and what it took to invent it.: https://youtu.be/BHyC2cwgkSA. Professor Ruan does distinguish the reflection of solar rays and emittance. It's subtle.

  4. Johnrlambert | | #7

    I am curious about the impact the ultra-white paint will have in the heating season. Sense it seems (to my limited understanding) that the paint is actively radiating its heat back toward the milky way, wouldn't this be net counter productive in certain climate zones?

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