Scientists have unveiled a white paint that can reflect the sun’s rays off the Earth’s surface, which could help cool the planet.
Dr Xiulin Ruan – a mechanics engineering professor at Purdue University – and his team first revealed the paint in 2020, which can reflect up to 98 per cent of the sun’s rays, the New York Times reported on Wednesday. The paint can cool surfaces up to eight degrees Fahrenheit in the middle of the day and up to 19 degrees Fahrenheit at night.
The paint itself is physically cool to the touch, Dr Ruan told the publication. Beyond this, the paint is award-winning: it earned a Guinness World Record in 2021 as the whitest paint ever.
“We weren’t really trying to develop the world’s whitest paint,” Dr Ruan said in an interview with the Times. “We wanted to help with climate change, and now it’s more of a crisis, and getting worse. We wanted to see if it was possible to help save energy while cooling down the Earth.”
It’s not so white that you can’t look at it, Dr Ruan added, because the paint disseminates light. His team is working on creating other colors that utilise the same white color as the base.
“They will work less ideally than the white, but better than some of the other commercial colors,” the professor said, adding that the paint is not yet available for commercial use.
Not everyone is so convinced that the paint is as ultra-effective as it is ultra-white. Even Dr Ruan noted that his team currently uses barium sulfate, which needs to be mined, and therefore has a negative environmental impact. However, he told the publication that his team’s paint is on par with other commercial ones, as most of them use titanium dioxide, which is also mined.
Dr Jeremy Munday, an electrical and computer engineering professor at University of California, Davis, told the New York Times that the effects of the paint are minimal.
“It’d be like pouring a cup of regular water into the ocean,” explaining that the sun generates a billion times more heat than the Earth, and the paint just reflects the sun’s heat.
Ultra-white paint or other methods of radiative cooling on a large scale is “definitely not a long-term solution to the climate problem,” Dr Munday said. “This is something you can do short term to mitigate worse problems while trying to get everything under control.”
