“The whitest paint in the world has been created in a lab at Purdue University,” reports USA Today, “a paint so white that it could eventually reduce or even eliminate the need for air conditioning, scientists say. “The paint has now made it into the Guinness World Records book as the whitest ever made.” Long-time Slashdot reader phalse phace shared their report: “When we started this project about seven years ago, we had saving energy and fighting climate change in mind,” said Xiulin Ruan, a professor of mechanical engineering at Purdue, in a statement. The idea was to make a paint that would reflect sunlight away from a building, researchers said. Making this paint really reflective, however, also made it really white, according to Purdue University. The paint reflects 98.1% of solar radiation while also 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. Using this new paint to cover a roof area of about 1,000 square feet could result in a cooling power of 10 kilowatts. “That’s more powerful than the air conditioners used by most houses,” Ruan said. Typical commercial white paint gets warmer rather than cooler. Paints on the market that are designed to reject heat reflect only 80% to 90% of sunlight and can’t make surfaces cooler than their surroundings… Researchers at Purdue have partnered with a company to put this ultra-white paint on the market, according to a news release. “This white paint is the result of research building on attempts going back to the 1970s,” adds a statement from Purdue University, “to develop radiative cooling paint as a feasible alternative to traditional air conditioners. “Ruan’s lab had considered over 100 different materials, narrowed them down to 10 and tested about 50 different formulations for each material…” Two features make this paint ultra-white: a very high concentration of a chemical compound called barium sulfate — also used in photo paper and cosmetics — and different particle sizes of barium sulfate in the paint. What wavelength of sunlight each particle scatters depends on its size, so a wider range of particle sizes allows the paint to scatter more of the light spectrum from the sun. Read more of this story at Slashdot.