Scientists recreate 2,000-year-old ‘golden fabric’ once worn by emperors and popes

Scientists in South Korea have recreated sea silk, a rare fabric once associated with emperors and popes, and have identified why its golden colour remains intact for centuries. 

The research was led by Professor Dong Soo Hwang of POSTECH’s Division of Environmental Science and Engineering and Division of Interdisciplinary Bioscience and Bioengineering, along with Professor Jimin Choi of the Environmental Research Institute. The findings were published in Advanced Materials.

The team used the pen shell, Atrina pectinata, a clam farmed in Korean coastal waters, to reproduce a shimmering golden fibre similar to one used more than 2,000 years ago. The researchers said the recreated fabric closely resembles historic sea silk and also helps explain the source of its distinctive and long-lasting golden sheen.

Sea silk, often called the ‘golden fibre of the sea’, was one of the most prized materials of the ancient Roman era. It was made from byssus threads produced by Pinna nobilis, a large Mediterranean clam that uses the threads to attach itself to rocks. The fabric was known for its luminous gold appearance, light weight and strength. One example often linked to the material is the Holy Face of Manoppello, a religious relic in Italy believed to be made from sea silk.

Traditional sea silk production has nearly disappeared because marine pollution and environmental damage have sharply reduced Pinna nobilis populations, pushing the species towards extinction. The European Union has banned harvesting the clam, leaving sea silk largely as a historical artefact, with only very small quantities still being produced by a few artisans.

To address this, the POSTECH team turned to Atrina pectinata, which is commonly raised for food in Korea and also produces byssus threads to anchor itself. The researchers found that byssus from Atrina pectinata closely matches the physical and chemical properties of original sea silk fibres. They then developed a method to process the pen shell threads and recreate the fabric.

The study also examined the reason behind sea silk’s golden glow. The researchers found that the colour does not come from dyes, but from structural colouration, which occurs when light interacts with nanoscale structures. According to the team, sea silk’s iridescence is created by a spherical protein structure called ‘photonin’. These proteins form layered arrangements that reflect light in a way similar to soap bubbles or butterfly wings. Because the colour comes from structure rather than pigment, it remains stable and resists fading over long periods.

The research points to a new use for pen shell byssus, which had earlier been discarded as waste, by turning it into a valuable textile. Professor Dong Soo Hwang said, ‘Structurally colored textiles are inherently resistant to fading. Our technology enables long-lasting colour without the use of dyes or metals, opening new possibilities for sustainable fashion and advanced materials.’