Cover by Korrina Gidwani

How Color is Saving the World One New Hue at a Time

By Miranda Scarborough

The colors of magnificent red poppies, eye-catching orange tiger lilies, ripe blueberries, and vibrant green leaves are all created by a plant’s pigmentation. But brilliant blues and lush greens are also reflected in the patterns of peacocks and many other birds. The truth is these animals use colorations that aren’t created by pigments, but through physical processes such as the scattering, absorption, and reflection of light. By producing elaborate displays, species  take resources used for other processes to increase survival and reproduction. Birds  use consumed pigments, fats, and oils from their diet to create intricate patterns in their feathers. The production of color is a difficult process for the animal kingdom and even humans have yet to perfect it synthetically. Science is getting close by using techniques found in nature to combat climate change and advance technology. 

There are three ways of producing color in nature: pigmentation, structure, and bioluminescence. Bioluminescence is produced chemically, for example by Cnidarians such as jellyfish, or symbiotically, like in giant fireflies of the Appalachians, that use organisms to glow. Inorganic ways to produce colors include the use of heavy metals, like cobalt, lead, and cadmium. In the past, these three commercialized metals were used to produce yellow, red, green, and blue pigments in paint. These heavy metals were found to accumulate in humans and produce effects such as cell death and nerve damage. Use of heavy metals in paints became illegal and new ways to produce pigments were needed. Blue hues of paint without use of heavy metals are less rich, but science has found new ways to fabricate shades of vibrant blues. 

For the first time in 200 years humans were able to create a new hue of blue. Creating a new color that produces reflectance in the UV region is a feat that even nature struggles with. The pigment, named YInMn Blue, is astounding because, like most scientific discoveries, it happened by accident . In 2009, a team led by Mas Subramanian, a professor at Oregon State, researching different materials used to cool electronics discovered YInMn Blue. Named after the elements yttrium, indium, and manganese that compose it, this new hue of blue created excitement because it is highly reflective of heat while being non-toxic, unlike its heavy metal counterpart Cobalt Blue. This new pigment could be utilized in exterior paints of buildings, other construction material, and electronics to increase cooling and reduce energy consumption. Further tests concluded that paint containing this pigment has a resistance to leaching from rainwater and contaminating ecosystems, unlike the normal behavior of its elemental components or heavy metal paints. 

         YInMn Blue is so special because it takes an aspect of nature and improves on it. Plants that produce pigments do not retain them indefinitely. They must continue to use resources and expend energy to create new pigments. YInMn Blue is a chemically derived blue that will not degrade over time, unlike organic pigments. Subramanian first noticed the distinct blue when the mixture was removed from an intense heat. The metals in the pigment retain a crystalline structure which provides the pigment with its stability and brightness. The crystalline structure absorbs light in the UV region and is highly reflective in the infrared region.  

“Birds exploit a lot of light and use it mostly for intraspecies communication,” Dr. David Outomuro, a professor at The University of Pittsburgh who has studied morphology and coloration in nature, explains. “They use a process called scattering. Scattering is like a prism; it projects the incoming light in multiple directions. What you get with scattering is not necessarily a rainbow every time. What color you see is what is reflected or scattered.” As you move the light source around you get the effect of a brighter, duller, or non-existent color. Birds produce their brilliant blues by the structural refraction of light from proteins found within their feathers, not by pigments like we find in plants. Birds produce these vibrant displays by building up six to eight layers of feathers that are positioned perfectly to refract light at different angles. When light hits an individual layer, it is cancelled out, absorbed, or refracted. When the light that has been refracted hits the next layer, part of the incoming light will be refracted again. All the refracted light summates to a brighter, more extravagant color, like in a peacock’s tail feathers. By mimicking this scattering process, scientists can produce colors that were only available to birds and insects without the use of toxic heavy metals. 

YInMn Blue is not the only pigment that is being tested for reductions in energy consumption. In October of 2020, Purdue university presented their newest shade of white, the whitest white ever created. Its creation also mimics the process that birds use.  Researchers used barium sulfate, common in other products such as photo paper and cosmetics, as the secret to the paint's immense reflectivity. The other secret is the scattering effect of the particles within the paint. By using large ratios of differently sized particles inside the paint, the amount of light scattered by each particle increases. The ratio may only be increased by so much before the paint is structurally compromised. If you have too many particles, the wavelengths of light will be interrupted and cancelled before it can reach our eyes. The implications of this highly reflective paint can reach as far as climate change. As human’s expand and build, more solar radiation is absorbed by light-guzzling products like asphalt and paint on the Earth’s surface. As the reflective ice caps around the Earth melt, less and less solar radiation is reflected by the Earth’s surface and more light is absorbed by the ocean and human development. This does not include other harmful effects such as greenhouse gasses, which absorb infrared light in the atmosphere and emit it back to the earth’s surface, raising the temperature. By using scattering, this white paint can reflect up to 98.1% of sunlight. Use of this  paint on buildings or roads will cause more solar radiation to be reflected, less infrared interference in the atmosphere, and a drastic reduction in the rate of climate change. 

Science is taking physics, chemistry, and biology to a new level in order to produce colors that have proved a tribulation for nature. Pigments  have been created by physiological processes to solve evolutionary problems such as plants attracting pollinators and seed dispersers or animals attracting mates. Now, science is using the same processes to create solutions to problems humans have caused. Scattering of light -- once seen only in bird feathers,  sunsets, and sunrises -- is now being used to combat climate change and promote sustainable processes in technology. Thinking ahead, could YInMn Blue and Purdue’s white pigment be the first to answer lingering questions of the reflection of solar radiation and energy consumption during space travel? Whatever answers may lie ahead, the creations of new hues have given humanity a new tool to move forward with. All we had to do was look to the natural world for inspiration.