Indeed, the "voids" the water droplets leave behind after evaporating can reflect up to 99.6-percent of light, the researchers found, across the IR, visible, and UV spectrums.

The paint’s porous structure holds water and slowly releases it, like the body does sweat. It reflects 88 to 92 percent of sunlight, even when wet, and emits up to 95 percent of the heat it absorbs.

Scientists have made an ultra-white paint that reflects 98.1% of the sunlight. And they think it might eliminate the need for air conditioning.

Although TiO 2 nanoparticles are used for white paint, they can be expensive, difficult to disperse evenly and they absorb UV light very strongly, Yu tells Physics World. Using air voids instead ...