'Ultimate white paint' that reflects 95.5% of light is developed

Using a carbon nanotube most black substance in the world and vantablack absorbs more than 99.9% of the impinging light, for irregularities and depth of the coated surface is not know, it has been applied as new material of the inner wall of the telescope and camouflage I will. Contrary to such vendor black, a paint that reflects more than 95% of the light that hits it has been developed.

Full Daytime Sub-ambient Radiative Cooling in Commercial-like Paints with High Figure of Merit: Cell Reports Physical Science
https://www.cell.com/cell-reports-physical-science/fulltext/S2666-3864 (20) 30236-8

This white paint could reduce the need for air conditioning by keeping surfaces cooler than surroundings --Purdue University News
https://www.purdue.edu/newsroom/releases/2020/Q4/this-white-paint-could-reduce-the-need-for-air-conditioning-by-keeping-surfaces-cooler-than-surroundings. html

You've Heard of Vantablack. Scientists Just Created'Super White', And It's Very Cool
https://www.sciencealert.com/you-ve-heard-of-vantablack-this-is-what-super-white-paint-can-do

High-temperature objects radiate thermal energy in the form of electromagnetic waves to the surroundings, causing ' radiative cooling ' that lowers the temperature. It has been pointed out that this radiative cooling also affects the heat island phenomenon and global warming, and the issue of 'how to suppress the temperature rise due to direct sunlight' has plagued scientists for many years.

The paint developed by the research team of the Department of Mechanical Engineering, Purdue University is a type of acrylic paint containing calcium carbonate . The conventional paint can only reflect 80-90% of the light that hits it at the maximum, but this new paint reflects 95.5% of the direct sunlight. As a result, objects coated with this paint are not warmed by direct sunlight and can be kept cooler than the ambient temperature even outdoors.

The following is an image of an infrared camera taken in an experiment conducted by the research team on the roof. The purple object on the left is the tile with the new paint, and the tile on the right is the tile with the commercially available white paint. You can see that the tiles with the new paint are cooler, even though they were both exposed to direct sunlight under the same conditions.

You can see the experiment on the roof from the following movie.

Radiative Cooling Paint-YouTube


The left is the new paint and the right is the conventional paint. The colors are slightly different, but you can hardly tell the difference.

Exposing the painted tiles to direct sunlight on the roof is Professor Xiulin Ruan of the Department of Mechanical Engineering, Purdue University, who led the research team.

At first glance, the tiles are just painted with white paint ...

Looking at it with an infrared camera that can measure temperature, only the acronym 'P' of Purdue University written with new paint is lower than the ambient temperature, and it appears blue.

The research team conducted a two-day field test based on various locations and weather conditions, and the part where the new paint was applied was about 10 ° C lower than the ambient temperature at night, and the effect of lowering the surroundings by about 1.7 ° C during the day. I found out that there is.

According to the research team, the new paint can be applied in much the same way as traditional paints, is resistant to abrasion and water when dry, and can withstand at least three weeks in an outdoor environment. The research team is proposing to combine fluorocarbon- based polymers to further increase the durability of the paint.

Also, the new paint manufacturing process is compatible with traditional paints, and manufacturing costs may be about the same or even lower. The name of the paint has not been decided yet.

Professor Ruan said, 'Developing a reliable solution for environmental radiative cooling with a practical single-layer particle matrix paint is a persevering research subject. This new paint has a wide range of applications for radiative cooling. , It is important to mitigate the effects of global warming. '