In October last year, scientists announced the creation of ultra-white paint, so reflective that it could be used to keep entire surfaces and buildings cool. This discovery has really pushed the envelope on new ways to combat global warming. Now, they have produced an even whiter paint.
Ultra-white paints are considered the opposite of vantablack, which absorbs 99.9% of light. They reflect so much light that a surface painted with them becomes colder than the ambient temperature around them.
The paint unveiled in October was based on calcium carbonate (CaCO3), the mineral that produces chalk. It had a reflectance of about 95.5%, which means that less than 5% of the sunlight that hit it would be absorbed as heat.
The new one, detailed in ACS Applied Materials & Interfaces magazine, uses barium sulfate instead, something that is already used commercially in paper and cosmetics. The team estimates that 98.1% of the sunlight is reflected by the new paint, which means that only 1.9% of the heat is absorbed.
“In our experiment, the new paint doubles the cooling power of the previous one,” senior professor Xiulin Ruan of Purdue University told IFLScience.
Tests showed that during the bright hours of the sun, the material covered in the new paint was 4.4 ° C (8 ° F) colder than ambient temperature. At night, the material kept a temperature of 10.5 ° C (19 ° F) below the surrounding areas.
This extraordinary cooling ability could change the game in the fight against global warming. This paint could be used to cool buildings instead of air conditioners.
The whitest square of white paint seen with a normal camera (left) and infrared (right). The infrared shows the temperature difference with the whitest paint cooling not only itself, but also the plate to which it is attached. Image credit: Purdue University / Joseph People
“Conventional air conditioners consume energy that often comes from burning fossil fuels. Meanwhile, as it moves heat from inside a house to the outside, it converts electricity into heat and leaves even more heat to the environment and the earth, further causing a heat island effect and warming the Earth, ”Professor Ruan explained. IFLScience.
“Instead, our paint does not consume any energy and sends all the heat directly to the deep space, thus helping to cool the Earth. According to a previous model, painting 0.5-1% of the Earth’s surface (roofs, roads, cars, unused land, etc.) with our paint will stop the warming trend. ”
While painting that fraction of the Earth’s surface could be very difficult, using paint on man-made structures could still have a major impact. The team has demonstrated that barium sulphate paint can withstand external conditions and is compatible with standard commercial paint processes. A paint patent has also been filed. If and when available for commercial use, this could be a simple solution to combat and mitigate the complex problem of global warming.
THIS WEEK IN IFLSCIENCE
Receive our greatest science stories in your weekly email inbox!
SUBSCRIBE TODAY!