Researchers at Purdue University in the United States (US) have set a world record for the whitest paint yet. While the paint was actually developed in October last year, it made its way into the Guinness Book of World Records earlier this month. The scientists claim that coating buildings with this paint were “cool off enough” to reduce the need for air conditioning, thereby eliminating a major cause of global warming today.
“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,” said Xiulin Ruan, a professor of mechanical engineering at the university, in a blog post earlier this year.
The paint is essentially the opposite of Vantablack, the blackest black material developed by British technology company Surrey Nanosystems in 2017. While Vantablack absorbs 99.9% of the light hitting its surface, this new paint reflects 98.1% of sunlight. A previous version of the paint reflected 95.5%, but the scientists improved its efficiency over time.
“Typical commercial white paint gets warmer rather than cooler. Paints on the market that are designed to reject heat reflect only 80%-90% of sunlight and can’t make surfaces cooler than their surroundings,” the blog post said.
The team also published a research paper on the paint back in April, which was the cover of the ACS Applied Materials & Interfaces journal on April 15. The journal is published by ACS Publication, which is a division of the American Chemical Society.
According to Xiangyu Li, a postdoc researcher at the Massachusetts Institute of Technology (MIT), who worked on the project, the scientists looked at the commercial products and found that barium sulfate could “theoretically” make surfaces “really, really reflective”, which means that they are “really, really white”.
“A high concentration of particles that are also different sizes gives the paint the broadest spectral scattering, which contributes to the highest reflectance,” said Joseph Peoples, a Ph.D. student in mechanical engineering at Purdue.