White was one of the first colors used in art in the 15th century, and one would think that there is little room left to improve its"whiteness". It turns out that is far from the case. A team of researchers led by Xiulin Ruan, a professor at Purdue University, recently revealed an"ultra-white"paint that they believe could even help fight climate change.
The scientists, who spent six years creating the world's "whites white"paint,
claim that the white paints currently available make surfaces warmer rather than cooler. That's because they only reflect 80 to 90 percent of the sunlight and cannot make surfaces cooler than the surrounding temperature. The newly-revealed ultra-white paint not only reflects 98. 1 percent of sunlight, but also prevents surface infrared（红外线的）heat from being absorbed.
"Our paint absorbs 1. 9% of sunlight, but those commercial paints absorb 10% of the sunlight --five times as much as our paint absorbs, "Dr. Ruan says. "They look white, they are pretty white, but they aren't white enough — they're not able to cool beyond the surrounding temperature. "
Outdoor tests of the new paint indicated it could keep surfaces 5℃ cooler than the surrounding temperature under the strong noon sunlight and as much as 10℃ cooler at night.
"We did a very rough calculation, "Dr. Ruan told a news reporter. "And we estimate we would only need to paint 1 percent of the Earth's surface with this paint-perhaps an area where no people live that is covered in rocks --and that could help fight the climate change trend. "
However, Hashem Akbari, professor of building at Concordia University, believes the paint's real benefits can only be proved after being in use for a few years. "Dirt and dust tend to decrease the reflectivity of the surface, "Akbari said. "If it starts with 95% reflectivity, the pollutants from the air could collect on the surface, and they decrease the reflectivity.
