Fibre encyclopedia
Silk
Also called silk · sutra · mulberry silk · sutera · SE
Protein filament reeled from a cocoon in one continuous length. Strong for its weight, weakened by sunlight and by alkali.
Class
Natural
Comes from
From an animal
Where it comes from
The silkworm spins a single filament to build its cocoon, and reeling recovers it whole rather than cutting it into staple. The filament arrives coated in sericin, a gum that is washed off in a step called degumming, which is what turns stiff raw silk into the cloth people recognise.
How it feels to wear
Air
Some air moves through the fibre
Water
Takes water into the fibre
Heat
Neither holds nor sheds heat
Stretch
A little stretch of its own
Wear
Holds up to ordinary rubbing
Silk is a protein, so it behaves more like hair than like a plant fibre: it takes water in, it holds dye deeply, and it is damaged by strong alkali, which is what most laundry detergent is. Sunlight breaks the protein chain, so a silk piece hung in a window loses strength where the light falls.
Care
- Hand wash cool with a neutral soap, or take it to a dry cleaner.
- Never bleach. Chlorine attacks the protein directly.
- Dry in shade, away from windows.
- Iron on the reverse, at the lowest setting.
Most silk labels say hand wash or dry clean for the same two reasons: alkali and sunlight.
End of life
Recycling route
No route running at scale
There is no volume collection for silk. Its second life is repair, resale and re-cutting, which is how the material has moved for as long as it has existed.
In a blend
Silk is often blended with viscose or polyester for cost and for handling, and a blend has no sorted route at all.
Skin notes
Mechanical
The filament is smooth and continuous, with no cut ends standing up at the surface, so there is no mechanical prickle route.
Chemical
Sericin can remain if degumming was partial, and silk takes acid dyes that a label never names.
If your skin reacts to a garment, a dermatologist and patch testing are what can answer it. A label cannot, and neither can this page.
What the label cannot tell you
The label says silk. It does not say how completely the gum was washed off, nor whether the cloth was weighted with mineral salts to add back the weight that degumming removed.
Sources
- Regulation (EU) No 1007/2011 on textile fibre names and related labelling, Annex I. Checked 22 August 2026
- ISO 3758:2023, Textiles, care labelling code using symbols. Checked 22 August 2026
Written from primary sources and in our own words. Where a figure could not be traced to a source anyone can open, it is not printed here.
Read the label you are holding
The scan surface reads one care label and names which questions it answers and which it leaves out. A passport says for one specific piece what a label cannot: the composition with its percentages, where the cloth came from, who worked on it, how to repair it and where it goes next.