Summer is here and the temperatures are already soaring in most parts of India. For those of us who have access to air conditioners, we’d love to have them on all the time. That would have serious repercussions, however, as global warming is a reality that we have to contend with. What if we had an easier way to cool down the places where we stay? What if painting the buildings a certain shade can provide enough cooling such that the need for air conditioners is reduced?
Researchers from Purdue University have done just that Building on their work from October 2020, the team has created an ultra-white paint that is not only the whitest ever, but also keep surfaces cooler than their previous formulation.
In a paper published in April 2021, researchers talk about their white paint which they believe might be the closet equivalent of ‘Vantablack” – the blackest black known which absorbs up to 99.9% visible light. While their formulation from October 2020 reflected 95.5% sunlight, their new ultra-white formulation reflects up to 98.1% sunlight.
Two features for whiteness
The very high concentration of a chemical compound called barium sulphate is one reason for the paint’s extreme whiteness. The other reason is that the barium sulphate particles in the paint are all of different sizes. This means that how much each particle scatters light is different and the paint as such scatters more of the light overall.
The whiteness of the paint in turn implies that it is the coolest paint available on record. Using thermocouples, which are high-accuracy temperature reading equipment, researchers were able to show that the paint can keep outdoor surfaces considerably cooler. Even in the middle of winter, when there is very little sunlight, the paint was still found to be working in lowering temperatures further.
A paint for cooling
While the current white paint is the result of six years of research, it builds an attempts going back much further. There have been efforts from the 1970s to come up with a radioactive cooling paint that can be an alternative to air conditioners.
Even though there is still scope to make the paint even whiter, researchers believe that it can’t be achieved without compromising the paint. As the technique used to create this white is close to how commercial paints are fabricated, a future where a coating of white might cool buildings and help curb global warming might indeed become a reality.
Picture Credit : Google
