How white paint could help save the planet
Many people assume that white paint is boring. It’s often found in rental flats and houses with no personality. However, scientists in the US have mixed a paint SO white that it reflects more than 98% of sunlight, making it more efficient for cooling than some air-conditioning units.
This paint could form part of the solution to tackle the climate crisis.
The study from Purdue University (Indiana) built upon studies from the 1970s to develop a ‘radiative cooling paint’ and after six years of research during which 100 different materials were tested, the scientists developed the whitest paint yet.
“If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners used by most houses,” said Xiulin Ruan, Purdue professor of mechanical engineering.
What makes the paint SO white?
There are two reasons why the paint is so ‘brilliant’. Firstly, the paint has a very high concentration of a chemical compound called barium sulphate, which is also used to make photo paper and cosmetics white.
“We looked at various commercial products, basically anything that’s white,” said Xiangyu Li, a postdoctoral researcher at the Massachusetts Institute of Technology, who worked on this project as a Purdue PhD student in Ruan’s lab. “We found that using barium sulphate, you can theoretically make things really, really reflective, which means that they’re really, really white.”
Secondly, the compound particles are all different sizes in the paint. How much each particle scatters light depends on its size, so a wider range of particle sizes allows the paint to scatter more of the light spectrum from the sun.
“A high concentration of particles that are also different sizes gives the paint the broadest spectral scattering, which contributes to the highest reflectance,” said Joseph Peoples, a Purdue PhD student in mechanical engineering.
Although the paint is already 98.1% white, there’s still a little wiggle room to make it EVEN whiter, but not much without compromising the paint.
“Although a higher particle concentration is better for making something white, you can’t increase the concentration too much. The higher the concentration, the easier it is for the paint to break or peel off,” Li said.
The technique the researchers used to create this paint is also compatible with current commercial fabrication processes, so there’s a chance we might be seeing it on shelves (or online) sometime soon!
Has this story changed your opinion of white paint?
This story was also reported on Positive News, where you can find more positive climate news.
For more information on the study, you can visit the Purdue University website.