The first time he saw the colour, the material scientist could not believe his eyes.
Back in 2009, when Prof. M.A. Subramanian of Oregon State University asked his new graduate student to grind a trio of dull oxides (of Y= Yttrium, In= Indium and Mn= Manganese) and bake the mixture at around1200 degrees centigrade, the idea was to make a multiferroic, a high-efficiency electronic material, which he imagined would be grey or black, not that he gave the color of the material much thought. What stared back from the furnace, the next day, was a dazzling blue powder.
Now, the solid-state chemist, with a PhD from IIT, Madras, had worked in DuPont Company for over twenty years and his industry instincts kicked in. He recalled colleagues from the pigment division saying that it was hard to make a blue compound in the lab. He asked his graduate student to repeat the experiment. He patented the brilliant blue material, which proved to be inert, non-toxic, and heat-reflecting though it was not the high-tech multiferroic he sought.
Turns out, Subramanian had discovered the first new blue pigment in more than two centuries. It was excellent for outdoor paints and coatings though it was not the multiferroic material he sought to make. Earlier in 2021, YInMn (pronounced Yin-Min) blue, which has already captured the imagination of the creative community, became available to artists as a paint. YInMn Blue is but the latest development in a long history of the quest for blue.
In Blue, In search of Nature’s Rarest Color, Kai Kupferschmidt, a correspondent for Science magazine, writes engagingly of the science and aesthetics of blues in nature, the history of blue dyes and pigments, and the ongoing quest for blues. Viewing the world through the lens of his favorite color, he finds plenty of information, which he presents in five sections: “Stones,” “Seeing,” “Plants,” “Speaking,” and “Animals.” The author even makes a batch of YInMn Blue in Subramanian’s lab to bedazzle himself anew.
The peacock on the book jacket, blue and beautiful, also represents the idea that most blue in nature is illusory. Blue-colored birds, beetles, and butterflies have tiny patterns on the surface of their bodies. These structures reflect light, so the blue wavelengths (380-500 nanometers) get exquisitely enhanced, while other wavelengths cancel out. Even the all-encompassing sky is not blue. Some plants make blue flowers and berries. There are a few blue minerals but extracting a durable blue pigment from natural sources is difficult. Blue has always demanded ingenuity.
Centuries before YInMn blue, another blue pigment had wowed the world. Ultramarine, once worth its weight in gold, was processed from lapis lazuli found in the Hindukush mountains. Michelangelo used ultramarine to depict the blue of the heavens in the Sistine Chapel. Later, synthetic ultramarine became a mass commodity. People use it for mundane things like making white laundry appear whiter. Its manufacture, however, is not ecologically friendly. And other synthetic blues have their own shortcomings.
Kupferschmidt, who writes clearly of the science of color, highlights what is not well understood by science as well. Scientists know how light interacts with the arrangement of atoms in an existing mineral to give it a distinct hue, but they cannot predict what color any new material will be without making it in the lab. Having pinned down the structure of YInMn blue, Subramanian’s group is changing components of the pigment to try and create other hues.
Elsewhere, researchers are on a quest for blue food colorants from plants. This is mostly because Consumers don’t like the fact that the same blue chemical, synthetic indigo, colors both their candy and their jeans. Currently, the only source of natural blue is spirulina, an extract of blue algae, which is neither vibrant nor durable, Kupferschmidt, writes. An English scientist has succeeded in making a safe, eye-catching blue from the petals of the butterfly pea flower, but the food industry needs a more durable colorant.
Meanwhile, Suntory, the Japanese whisky manufacturer, backs an effort to create a blue rose through genetic engineering. In over two decades, the researchers behind the effort have made it to mauve but hope to get to true blue in the near future.
“Seeing” and “Speaking” are sections of the book that deal with how we perceive and describe color. Take the cornflower, for instance. It absorbs the red part of the spectrum from white sunlight and reflects (or rejects) all the rest. The eye transforms the reflected light, which appears blue, into electrical signals for the brain to process. Language provides the beholder with the prescribed shade of color. “Where then is the blue,” Kupferschmidt muses philosophically.
But blue is not illusory or abstract. Even the blind can sense blue light. They grow more alert in its presence. So, what is its impact on the sighted, who are increasingly bathed in the blue glow of electronic devices, well into the night? Can patients rest well in clinical wards, under artificial lights, rich in blue wavelengths? Such research is already changing internal lighting in homes and hospitals.
In the closing pages, when you read that the Berlin-based author, born in 1982, has tested HIV-positive, you cannot help feeling blue. When he resolves to look out into the world more often, as if he were seeing all its colors for the very first time, you feel inspired. Thanks to this authoritative biography of blue, most curious readers will get a new understanding of the science of color. Scientists too may begin to appreciate works of art.
These days, Subramanian accompanies his wife to art museums, to see what magic the old masters have wrought – especially with the blue pigments. YInMn blue, he says, has enriched his life in more ways than one.
