Last October, scientists announced that the manufacture of ultra-white paint is so reflective that it can be used to keep surfaces and even entire buildings cool. That breakthrough drove the envelope in new ways to fight global warming. Now they have made an even whiter paint.
The ultra-white paint is considered the opposite of vantablack, which absorbs 99.9 percent of the light. They reflect so much light that a surface painted with it becomes cooler than the ambient temperature.
The paint revealed in October was based on calcium carbonate (CaCO3), the mineral that makes chalk. It has a reflection of about 95.5 percent, which means that less than 5 percent of the sunlight it hits would be absorbed as heat.
The new one, outlined in the journal ACS Applied Materials & Interfaces, uses barium sulfate instead, something that is already used commercially in paper and cosmetics. The team estimates that 98.1 percent of the sunlight is reflected by the new paint, which means that only 1.9 percent of the heat is absorbed.
“In our experiment, the new paint doubles the cooling power of the previous one,” senior author Professor Xiulin Ruan of Purdue University told IFLScience.
Tests showed that the material covered in the new paint was 4.4 ° C (8 ° F) cooler than the ambient temperature during strong sunlight. At night, the material maintained a temperature of 10.5 ° C (19 ° F) below the surrounding areas.
This extraordinary ability to cool down can be a game changer in the fight against global warming. This paint can be used to cool buildings instead of air conditioners.
The whitest white paint squared seen with a normal camera (left) and in infrared (right). The infrared shows the temperature difference with the whitest paint cooling, not only itself, but also the board on which it is attached. Image Credit: Purdue University / joseph peoples
‘Conventional air conditioners consume power that often comes from burning fossil fuels. As they move the heat from inside a house to the outside, they convert the electricity into heat and leave even more heat to the environment and earth, which further causes a heat island effect and warms the earth, ‘explains Professor Ruan to IFLScience.
‘On the other hand, our paint consumes no power, sending it directly all the heat to deep space and helping it cool the earth. According to a previous model, the heating will tend to paint 0.5-1% of the earth’s surface (roofs, roads, cars, unused land, etc.) with our paint.
Although it can be very difficult to paint the part of the earth, the paint can still have a big impact on human structures. The team has shown that the barium sulphate paint can handle outside conditions and is compatible with standard commercial painting processes. A patent for the paint was also filed. If available for commercial use, it can be a simple solution to combating and mitigating the complex issue of global warming.
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