Could the feather nanostructure making up birds' multicolored plumage be the key to producing non-fading paint and fabric colors?
Thanks to this structure based on light manipulation and not mere dyes and pigments, blue jays never turn gray even with aging — something that manufacturers could use to cheaply make paints and clothes that won't see their colors fade over time.
The University of Sheffield team led by Dr. Andrew Parnell used X-ray scattered at France's ESRF facility to study the jay's blue and white feathers, which were part of the massive collection of the Natural History Museum in London.
The researchers published their findings on Dec. 21 in the journal Nature Scientific Reports.
Spongy Feather Nanostructure
What they discovered: the birds' vibrant feathers come from the well-controlled changes to their feather nanostructure, also possibly a way for the jays to recognize each other. Using this tuneable structure, the birds were also found to change their feathers' colors along a feather barb, which is the equivalent of a single human hair.
Dr. Parnell from the University's physics and astronomy department highlighted the possibility of using this natural mechanism to go beyond current dyeing and pigment-based technologies.
"Now we've learnt how nature accomplishes it, we can start to develop new materials such as clothes or paints using these nanostructuring approaches. It would potentially mean that if we created a red jumper using this method, it would retain its colour and never fade in the wash," he said in a press release.
The nanostructured spongy keratin, which makes the blue jay's feathers turn from ultra violet to blue to white, is identical to the material that forms human hair and fingernails.
Light Manipulation
The team also found that the jays ably controlled the size of the sponge-like structure's holes, fixing them at highly specific sizes and determining the color reflected from the feather. This occurs because as light hits the feather, each hole's size determines the way light is scattered and what color is exhibited.
Larger holes in the structure create white, while smaller, more compact ones lead to a blue shade.
Since the colors are produced from structural techniques as nature designed and not from pigments emerging from the birds' diet, the birds never turn gray as they age. Humans, on the other hand, rely on pigments, which explain gray hairs during old age.
For Dr. Parnell, one can replicate this fascinating process for human use.
"[I]f nature can assemble this material 'on the wing', then we should be able to do it synthetically too," he said, adding that the density and size of the spongy structure's holes could be manipulated to decide on colors to be reflected.
Co-author Dr. Adam Washington added that this new finding also answers why nature rarely offers non-iridescent structural green colors. The color green is deemed highly complex and needs narrow wavelength — something that is hard to replicate.
"Nature's way to get round this and create the colour green — an obvious camouflage colour — is to mix the structural blue like that of the jay with a yellow pigment that absorbs some of the blue colour," he explained.
AkzoNobel, the makers of Dulux paint, welcomed the research development to promote eco-premium benefits in their line of products.
"This exciting new insight may help us to find new ways of making paints that stay brighter and fresher-looking for longer, while also having a lower carbon footprint," said Dr. Daragh McLoughlin of its research team.
The blue jay, with the scientific name Cyanocitta cristata, comes from the Corvidae family and is native to North America. According to BirdLife International, the species has an extremely large population and therefore not yet facing any significant threats or fluctuations in numbers.
