Whitest-Ever Paint Could Help Cool Heating Earth, Study Shows
samedi 17 avril 2021, 04:02 , par Slashdot
AmiMoJo shares a report from The Guardian: The whitest-ever paint has been produced by academic researchers, with the aim of boosting the cooling of buildings and tackling the climate crisis. The new paint reflects 98% of sunlight as well as radiating infrared heat through the atmosphere into space. In tests, it cooled surfaces by 4.5C below the ambient temperature, even in strong sunlight. The researchers said the paint could be on the market in one or two years. Currently available reflective white paints are far better than dark roofing materials, but only reflect 80-90% of sunlight and absorb UV light. This means they cannot cool surfaces below ambient temperatures. The new paint does this, leading to less need for air conditioning and the carbon emissions they produce, which are rising rapidly.
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. The researchers said the ultra-white paint uses a standard acrylic solvent and could be manufactured like conventional paint. They claim the paint would be similar in price to current paints, with barium sulphate actually cheaper than titanium dioxide. They have also tested the paint's resistance to abrasion, but said longer-term weathering tests were needed to assess its long-term durability.
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