The Challenge of Replicating Nature's Most Vivid Colors
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Chapter 1: The Artistic Inspiration
The journey of German artist Franziska Schenk began with a captivating image of a sparkling blue fish, specifically the West Indian Ocean coelacanth. "It was both mysterious and beautiful," she recalls, reflecting on her childhood fascination with the sea. This initial inspiration set her on a quest to capture the elusive beauty of nature through her art. Schenk’s goal of creating iridescent paintings not only posed a significant technical challenge but also compelled her to delve into the unique ways nature produces color.
Her first major projects involved creating large portraits of formidable fish known as grouper. However, her attempts to incorporate a radiant golden background were thwarted by the yellow paints she experimented with, which she described as “dull.” “The vibrant golden and familiar silver hues of iridescence found in numerous fish resemble actual precious metals,” she noted. Frustrated by her inability to find a paint that could replicate the mesmerizing shimmer that captivated her, she expressed her desire: “I wanted to use the same technology as the fish.”
After a year of dedicated experimentation, Schenk finally learned how to transform powder into a usable paint while preserving its optical characteristics.
Section 1.1: Understanding Structural Color
For centuries, researchers have been striving to unveil the mysteries behind structural color, the phenomenon responsible for some of nature's most breathtaking shades. In 1730, Sir Isaac Newton proposed that the shimmer of peacock feathers resulted from light being split like a prism, a theory that, while insightful, was incomplete. By the early 19th century, physicist Thomas Young discovered that the wave nature of light could clarify how thin transparent films create iridescence.
Unlike traditional pigments, which generate color by absorbing certain light wavelengths, structural colors operate differently. When light hits a thin film—like that of a soap bubble—some of it reflects off the top surface, while the rest penetrates through, reflecting off the bottom edge before returning upward. Young realized that the combination of these light waves results in some wavelengths being intensified and others diminished, leading to the striking colors we observe. Moreover, the angle from which we perceive these colors influences their iridescent quality, explaining why they seem to shift when viewed from different perspectives.
This understanding of iridescence became a crucial part of Schenk’s artistic process. During her residencies with scientists, she learned about various examples of this phenomenon in nature. For instance, at a British aquarium in 2004, she studied the cuttlefish, which utilizes specialized skin elements called chromatophores to blend into its environment. Later, her residency at the Natural History Museum in London allowed her to observe the iridescent Morpho butterflies, whose wings exhibit a deep azure hue derived from layered structures of chitin.
Section 1.2: Creating Iridescent Paints
Schenk was determined to formulate iridescent paints suitable for canvas. Many commercially available options claimed to be iridescent but yielded only pale, lackluster colors, failing to capture the vibrant shimmer found in nature. Eventually, she acquired high-quality iridescent materials that were expected to produce shimmering shades of purple, gold, and red. Surprisingly, these materials appeared as dull grey powders, unlike any pigment she had encountered. They consisted of tiny silica flakes coated in multiple layers of metal oxides.
It took a year of trial and error for Schenk to figure out how to convert this powder into a paint that maintained its optical properties. Additionally, she had to master the art of blending her iridescent paints into a cohesive color palette. "It was counterintuitive," she shared. Unlike traditional pigments where mixing yellow and blue yields green, her new paints followed additive color rules similar to light mixing. “Mixing gold and metallic blue resulted in white … I had to unlearn everything I knew about color theory.”
Chapter 2: Nature’s Palette
Incorporating nature's color strategies into her work became the next challenge. For example, the magenta spots on the wings of Colotis butterflies combine a red pigment with layered reflectors to produce a blue sheen. “My paintings evolved to reflect the layered construction of butterfly wings,” Schenk explained. In 2013, she successfully recreated the orange underside of the Japanese jewel beetle, its green top, and violet stripes, verifying their accuracy through reflectance measurements.
Schenk’s artwork has been showcased in Germany, the UK, and will soon be displayed in the Netherlands. Her paintings possess a realism akin to photographs, yet they shimmer and flash, capturing the dynamic essence of iridescent specimens in a manner that static images cannot. The colors shift as viewers move, akin to the butterfly and beetle features depicted in her work. "It's almost a competition between the photograph and the painting," Schenk mused. "For now, I’m ahead."
Eli Kintisch is a correspondent for Science magazine and the author of the book, Hack the Planet, which delves into geoengineering and its potential to combat climate change.