Cupro (Vegan Silk)
A silky, breathable regenerated cellulose fibre made from cotton linter waste in a closed-loop process — often marketed as 'vegan silk'.
What it is
Cupro (cuprammonium rayon) is a semi-synthetic fibre spun from the tiny cotton linters left on the seed after ginning. The linters are dissolved in a copper-ammonia solution, extruded into filaments, and the solvents are recovered and recycled in a closed-loop system pioneered by Asahi Kasei's Bemberg™ mill in Japan.
Why it matters
Cupro turns a cotton by-product that would otherwise be waste into a silk-like fabric with none of the animal welfare issues of silkworm silk. When produced in a certified closed-loop facility, solvent recovery is above 99%, and the finished fibre is biodegradable and compostable under industrial conditions.
Upsides
- Uses cotton linter — a waste stream from conventional cotton production
- Closed-loop solvent recovery (>99%) at Bemberg's Japanese mill
- Fully biodegradable and compostable at end of life
- Vegan and cruelty-free alternative to mulberry silk
- Breathable, thermoregulating, hypoallergenic, machine-washable
Trade-offs
- Only one certified closed-loop producer worldwide — most 'cupro' on the market has no traceable origin
- Uncertified cupro can be produced with heavy metal (copper) discharge to waterways
- Still a resource-intensive chemical process compared to lyocell
- Often blended with elastane or polyester, which kills biodegradability
What to look for on the label
'Bemberg™ by Asahi Kasei' on the composition label, or a supplier chain-of-custody document. Look for OEKO-TEX Standard 100 certification and 100% cupro content — avoid blends with synthetics if biodegradability matters to you.
Better or comparable alternatives
Frequently asked
Is cupro fabric sustainable?+
Bemberg™ cupro from Asahi Kasei is one of the more sustainable silk alternatives — it upcycles cotton linter waste and recovers over 99% of its solvents in a closed loop. Generic, uncertified cupro is not: it can discharge copper and ammonia into waterways. Always check for the Bemberg™ trademark or a verified chain-of-custody document.
Is cupro a vegan silk?+
Yes. Cupro is plant-based (cotton linter cellulose) and made without silkworms, so it is fully vegan. It drapes and feels similar to silk, but it's a regenerated cellulose fibre, not an animal protein.
Is cupro biodegradable?+
Pure 100% cupro is biodegradable and compostable under industrial conditions in a few months. Blends with polyester, nylon, or elastane are not — always check the composition label.
Cupro vs lyocell — which is more sustainable?+
Lyocell (Tencel) generally has a lower environmental footprint because its NMMO solvent process is simpler and its FSC-certified wood pulp feedstock is traceable. Cupro wins on feedstock (using a waste stream) but only when produced in the Bemberg™ closed-loop mill.