Silk fibres with substantially greater tensile strength and sharply reduced shrinkage under wet conditions have been produced by altering the diet of silkworms rather than treating the fibres directly. Researchers at Tohoku University added plant-derived cellulose nanofibres to silkworm feed, achieving a 50% tensile strength gain and shrinkage below one-quarter that of untreated silk, with the resulting "super silk" retaining these improvements through yarn spinning and fabric weaving.
- Adding cellulose nanofibres to silkworm feed produced measurably stronger fibres without chemical treatment or any changes to the existing production process.
- Dimensional stability gains under wet conditions were confirmed across both yarn and woven fabric forms, from individual fibres through to finished woven cloth.
- Conventional silk has a known weakness in repeated moisture exposure, causing it to shrink and lose shape, a limitation the new dietary approach largely resolves.
- The findings have been published in the paper 'Researchers create strong super silk that maintains shape after wetting', Journal of Industrial Textiles.
BEHIND THE RESEARCH: Silk has been prized for more than 4,000 years as a luxury material, valued for being lightweight, strong and biocompatible (meaning it is safe for use in contact with living tissue) across clothing, medical and industrial applications. The study tested whether a dietary intervention at the silkworm stage could deliver performance gains that endure through subsequent processing, building on previous work by the same research team.
- The research was led by Associate Professor Hiroki Kurita, whose prior work had established the foundation for the CNF dietary intervention approach.
- Silk's established uses extend across a range of industries beyond fashion, including clothing, medical materials and other industrial applications.
- A key research question was whether benefits would survive the subsequent stages of spinning and weaving, which the previous work had not tested.
- The study assessed fibre performance at each stage of processing, from individual fibres through to spun yarn and woven fabric, to determine whether dietary gains held through to finished textile form.
WHAT THE NUMBERS SAY: The Tohoku University findings show a 50% increase in tensile strength relative to conventional silk and a reduction in shrinkage to less than one-quarter of untreated levels. Both improvements held when fibres were processed into yarn and woven into fabric, with results consistent across the full textile production chain.
- Performance gains held when fibres were processed into yarn and woven into fabric, confirming the method's reliability beyond the individual fibre stage.
- Silk's long-standing vulnerability to moisture-induced deformation has been directly targeted by this research, with dimensional stability gains confirmed across both yarn and woven fabric forms.
- The method requires only a small addition of sturdy CNF to silkworm feed, offering a practical route to stronger, more stable silk without chemical intervention or extensive process modifications.
- Results showed the dietary approach achieved simultaneous gains in both tensile strength and dimensional stability without altering silk's inherent material properties.
- The researchers suggest the sustainable approach may contribute to the development of next-generation functional textiles.
WHAT THEY SAID
Silk is not just for fashion — it is also used in a plethora of different industries you might not initially think of… Our goal was to improve silk while preserving its natural advantages. We were excited to find that simply changing the silkworms' diet produced silk that is both stronger and much more dimensionally stable in wet environments.
— Hiroki Kurita
Associate Professor
Tohoku University
