In 2020, scientists at Purdue University developed a new super-white acrylic paint that reflects 95.5% of sunlight. Since then, they've made it even whiter, with a new formula that increased sunlight reflection to 98.1%, which sets the Guinness World Records record for the whitest ink.
"We weren't really trying to develop the whitest paint in the world," Xiulin Ruan, a Purdue professor of mechanical engineering who oversaw the research, told the New York Times. "We wanted to help with climate change, and now it's another crisis and it's getting worse. We wanted to see if we could help save energy and cool the Earth at the same time."
Since the paint scatters sunlight as it reflects it, there is no glare effect. But while ultrawhite may look similar to the paint shades you can buy at Home Depot, the newly developed paint is far more effective as a cooling tool than its more light-absorbing counterparts.
What does this mean in practice? Purdue's ultra-white ink keeps surfaces cool to the touch, even in scorching heat. Compared to mid-afternoon air temperatures, a surface painted the whitest white can be eight degrees Fahrenheit cooler. At night, the difference is even more pronounced, reaching 19 degrees.
Painting buildings the whitest white can help offset the urban heat island effect caused by most man-made buildings absorbing more heat than natural landscapes, causing temperatures to rise.
"We found that using barium sulfate, you can theoretically make things very, very reflective, which means they are very, very white," Xiangyu Li, who was a student in Ruan's lab, said in a statement, noting that a higher concentration of barium sulfate particles increases reflectivity, but adding too much makes the paint prone to cracking.
White paint has long been used in hot climates on roofs and building exteriors to try to keep homes cool, but because traditional paints only reflect 80% to 90% of sunlight, the heat continues to build.
With that whiter white, it's almost as if Ruan has created an air conditioner that runs on zero energy - and without the downside of emitting heat outside even as the A/C cools the interior. The air conditioning needs of a building coated with barium sulfate paint are expected to decrease by up to 40 percent.
Purdue developed the whitest white for use on roofs, but interest in the paint has been widespread.
Source: NewYorkTimes