A fabric once reserved for emperors and popes has been recreated in South Korea, and researchers say its famous golden shine comes from the fiber’s structure, not from dye.
A team led by Professor Dong Soo Hwang of POSTECH’s Division of Environmental Science and Engineering and Division of Interdisciplinary Bioscience and Bioengineering, and Professor Jimin Choi of the Environmental Research Institute, recreated a golden fiber similar to ancient sea silk using the pen shell, Atrina pectinata, a shellfish cultivated in Korean coastal waters.
The findings were published in Advanced Materials.
Sea silk, often called the “golden fiber of the sea,” was highly prized during the Roman era. It was made from byssus threads produced by Pinna nobilis, a large Mediterranean clam that uses the fibers to anchor itself to rocky surfaces.
The material became known for its shimmering golden color, light weight and durability. One of the best known examples is the Holy Face of Manoppello, a religious relic preserved in Italy for centuries that is believed to have been made from sea silk.
In recent decades, marine pollution and environmental decline have pushed Pinna nobilis toward extinction. The species is now endangered, and the European Union has banned its harvesting.
To find another source, the researchers studied Atrina pectinata, which is already farmed for food in Korean waters. They found its byssus fibers closely resembled those of the Mediterranean clam, physically and chemically, then developed a way to process the pen shell fibers into a material that recreates the appearance of ancient sea silk.
The team also identified why sea silk keeps its color for so long. The golden effect does not come from pigments or dyes. It comes from structural coloration, in which microscopic structures interact with light to produce color.
The researchers found sea silk’s iridescent appearance comes from layered spherical protein structures called “photonin.” They also found that the more precisely these proteins are organized, the stronger and more vivid the color becomes.
Because the color comes from the material’s structure rather than added pigments, it remains highly stable over long periods. The researchers said that helps explain how sea silk can keep its brilliance for centuries.
The study also points to a use for pen shell byssus fibers, which have traditionally been discarded as waste. The researchers said converting them into textile material could reduce marine waste while producing sustainable materials with cultural and historical significance.
Professor Dong Soo Hwang said, “Structurally colored textiles are inherently resistant to fading. Our technology enables long-lasting color without the use of dyes or metals, opening new possibilities for sustainable fashion and advanced materials.”
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