Flying colours: Butterflies are inspiring an entirely new approach to paint

After years of studying how colourless scales on their wings cause iridescence, researchers have made a paint of clear nanoparticles that scatter,diffract light

Chemistry and physics are all very well, but the future of paint could well be geometric. And our guides in this field, are butterflies.

The lessons aren’t coming from their powdery pigments, but from their iridescence, which is the result of an intricate network of scales on their wings.

These scales have no inherent colour. They are, instead, layered and separated by pockets of air. This scatters and diffracts light, often several times across the tiny span, causing the flashes

The structural colour is produced in the form of nanoflakes and combined with a commercial-grade binder to make paint. (Courtesy Debashis Chanda / UCF)

The other colour is a specific deep red. “For this, we have to further optimise our parameters to suppress all blues and greens so that only light at 633 nanometres is reflected back. We still have to work that out, but we’ll get there eventually,” Chanda says

The paint has other interesting properties. The particles are 1,000 times wider than they are thick. As a result, this paint achieves full opaque coverage at a thickness of 150 nanometres, making it thousands of times lighter than the current lightest paints in the world.

It is also has the potential to act as an energy-saving device. “Because the multilayer stack is designed to resonate only with the spectrum of light visible to humans, it completely reflects every other wavelength of light that it is not interacting with, including infrared light – which is notorious for heating the earth – and thus helps keep a surface cool,” Chanda says.

The next step will be to work towards commercial viability. “It’s all very exciting,” says Chanda. “The possibility of a widely available, non-toxic, ultralightweight, cooling paint could change up the industry for the better.”