The whitest coating worldwide

Researchers at Purdue University in Indiana/USA have now developed what they claim is the whitest coating with which they want to make a contribution to lowering temperatures and energy consumption.

whitest paint heat signature
An infrared camera shows how a sample of the whitest white coating (right) actually cools the board below ambient temperature Phto: Purdue University/Joseph Peoples

Surfaces coated with the new developed whitest coating thisin the building sector require less energy to be cooled with air conditioners,for example – regardless of the substrate. If, for example, a metal roof ofabout 100 m2 is coated, a cooling capacity of 10 kW can be achieved – that ismore than usually used central air conditioning systems in buildings canachieve. Outdoor measurements showed that the coated surfaces remain 10.5 °C cooler than the ambient temperature at night and 4.5 °Ccooler during the day when the sun is shining strongly. Even in winter, thereflective power of the coating is evident: at an ambient temperature of only 6°C, that of the test object dropped by 3.8 °C.

Extremly high refelection of solar irradiation

The formulation reflects IR heatas well as up to 98.1% of sunlight. The decisive factor for the high degree ofwhiteness is the pigment barium sulphate, which can be implemented in the paintas nanoparticles and nanocomposites. Another effect that increases whiteness isthat the barium sulphate particles have very different sizes. How much sunlightthe particles can reflect depends on their size; many different sizes can thuscover a wider spectrum of sunlight.

It has been shown that the concentration ofparticles must not be too high, otherwise cracks or adhesion problems willoccur. The research project, which was completed last year, was funded by theDefense University Research Instrumentation Program (DURIP), among others. Thereflective coating has already been registered as a patent.

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