The paint, created by researchers at Purdue University, reflects 98.1 percent of sunlight and thus can cool down buildings all on its own

By Eric Todisco
April 20, 2021 01:30 PM
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Ultrawhite Paint
ultra white paint
| Credit: Jared Pike/Purdue University

A new "ultra-white" paint created by scientists may play a major role in the ongoing fight against climate change.

Researchers at Purdue University recently created the whitest white paint, which can absorb approximately 98.1 percent of sunlight and thus can cool down buildings all on its own. These findings, which were part of a six-year study, were published as the cover of the journal ACS Applied Materials & Interfaces on April 15.

"If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That's more powerful than the central air conditioners used by most houses," Xiulin Ruan, a professor of mechanical engineering at Purdue, said in a news release.

Unlike regular paint, which typically reflects only 80 to 90 percent of sunlight and can't make surfaces cooler than their surroundings, the ultra-white paint contains barium sulfate, a chemical compound that is used to make photo paper and cosmetics white.

The barium sulfate particles are all different sizes in the paint, which explains how they "scatter" the sun's rays and cool surfaces, the university said.

Ultrawhite Paint
ultrawhite Paint
| Credit: Joseph Peoples/Purdue University

"We found that using barium sulfate, you can theoretically make things really, really reflective, which means that they're really, really white," said Xiangyu Li, a researcher on the project.

Joseph Peoples, a Purdue Ph.D. student in mechanical engineering, added, "A high concentration of particles that are also different sizes gives the paint the broadest spectral scattering, which contributes to the highest reflectance."

The researchers also believe that the new white paint is the equivalent of the blackest black, Vantablack, which absorbs up to 99.9 percent of visible light, the news release said.

Lukas Schertel, an expert in light scattering from the University of Cambridge, told CNN that if the ultra-white paint was used on a mass scale, such as on generators and other machinery that radiate heat, it "could have a global impact on energy efficiency."

However, the struggle would be in encouraging the manufacturer to make the paint scalable and affordable, Schertel told CNN.

Research on the ultra-white paint began six years ago and there have been attempts dating back to the 1970s to develop radiative cooling paint as an alternative to air conditioners.