On solution to avoid catastrophic climate change is as easy as painting buildings. It’s known that white pain has benefits for cooling cities and on individual buildings it can reduce the use of air conditioning. This has led to a wider adoption of white paint on buildings, and more research into making a more reflective white paint. Prof Xiulin Ruan at Purdue University in the US alongside a team of researchers has created the most reflective white paint ever!

The new paint was revealed in a report in the journal ACS Applied Materials & Interfaces. Three factors are responsible for the paint’s cooling performance. First, barium sulphate was used as the pigment which, unlike conventional titanium dioxide pigment, does not absorb UV light. Second, a high concentration of pigment was used – 60%.

Third, the pigment particles were of varied size. The amount of light scattered by a particle depends on its size, so using a range scatters more of the light spectrum from the sun. Ruan’s lab had assessed more than 100 different materials and tested about 50 formulations for each of the most promising. Their previous whitest paint used calcium carbonate – chalk – and reflected 95.5% sunlight.

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