A new textile process has produced the darkest wool fabric yet reported, achieving near-total light absorption through a nature-inspired surface structure. The method combines a synthetic melanin dye with plasma etching to create nanoscale fibrils that trap incoming light within the fabric. The result is an ultrablack material that remains visually stable across wide viewing angles and is suitable for wearable use.
- The process involved dyeing white merino wool with polydopamine before plasma etching selectively removed fibre surfaces to form dense, spiky nanofibrils.
- These nanoscale fibrils force light to bounce repeatedly within the fabric structure, preventing reflection and creating a uniform ultrablack appearance across viewing angles.
- Optical analysis showed the fabric achieved an average total reflectance of 0.13 per cent and retained consistent blackness across a 120-degree angular span.
- The study ‘Ultrablack Wool Textiles Inspired by Hierarchical Avian Structure’ was authored by Larissa Shepherd and colleagues and published in Nature Communications.
THE STUDY: The research originated in Cornell University’s Responsive Apparel Design Lab within the College of Human Ecology, where researchers examined how ultrablack colouration occurs in the feathers of the magnificent riflebird. By translating this biological structure into a textile context, the study investigated whether similar light-trapping effects could be engineered in natural fibres. Experimental work focused on wool fabrics and combined dye chemistry with surface modification to validate optical performance.
- The work was led by the lab’s director and involved doctoral researchers specialising in textile design, materials science and biomimetic analysis.
- Feather samples from the riflebird, sourced from the Cornell University Museum of Vertebrates, were analysed to understand how melanin pigment and tightly packed microstructures jointly suppress light reflection.
- The study tested whether these biological principles could be reproduced in textiles without relying on specialised dyes or non-wearable substrates.
- Laboratory analysis assessed optical behaviour after treatment, focusing on reflectance reduction and stability across different viewing angles.
INSIDE THE PROCESS: The textile process relies on a sequential treatment combining internal dye penetration with controlled surface modification to suppress light reflection. Wool fabric is first dyed using polydopamine, a synthetic analogue of melanin, ensuring the colourant penetrates the fibre interior rather than remaining on the surface. The fabric is then plasma-etched, selectively removing outer material to form dense nanoscale fibrils that redirect incoming light inward.
- Polydopamine was selected because its chemical similarity to natural melanin supports broadband light absorption within the fibre structure.
- Plasma etching removes a thin surface layer from individual fibres, leaving behind spiky nanofibrils critical to the light-trapping effect.
- These fibrils cause incoming light to bounce repeatedly between nanoscale structures, reducing back-reflection and limiting light escape without relying on pigment density alone.
- Full fibre penetration was necessary because surface-only coatings would be partially removed during etching, weakening the ultrablack effect.
- The combined chemical and physical approach allows the fabric to retain flexibility and wearability while achieving extreme optical absorption.
WHAT IT DELIVERS: Optical testing showed that the treated wool fabric achieved the lowest light reflectance reported for a textile, while maintaining consistent appearance across different viewing positions. The ultrablack effect remained stable over a wide angular range, addressing a common limitation of existing ultrablack materials. The process was also demonstrated on natural fibres beyond wool, including silk and cotton, supporting claims of scalability and practical application.
- Measurements recorded an average total reflectance of 0.13 per cent, confirming extreme suppression of reflected light under laboratory testing conditions.
- The fabric retained its ultrablack appearance across a 120-degree angular span, avoiding the sheen seen in angle-dependent materials.
- The treatment was shown to work on natural fibres including wool, silk and cotton, indicating material versatility.
- Potential applications highlighted include wearable apparel, optical devices, solar thermal energy conversion systems and thermo-regulating camouflage.
- Researchers have applied for patent protection through the Cornell Center for Technology Licensing and indicated interest in forming a company to commercialise the process.
WHAT THEY SAID
From a design perspective, I think it’s exciting because a lot of the ultrablack that exists isn’t really as wearable as ours. And it stays ultrablack even from wider angles.
— Larissa Shepherd
Assistant Professor, Department of Human Centered Design
Cornell University
The light basically bounces back and forth between the fibrils, instead of reflecting back out – that’s what creates the ultrablack effect.
— Hansadi Jayamaha
Doctoral Researcher, Responsive Apparel Design Lab
Cornell University
