Silk is the filament a silkworm spins to build its cocoon, and the standard way to harvest it kills the pupa inside before it can chew its way out and cut the thread. Peace silk lets the moth go free, but the insect is still farmed for its fibre.
Made fromCocoon filament spun by the silkworm, Bombyx mori
How it's harvestedCocoon is steamed, boiled or baked to kill the pupa inside
Vegan swapsTencel/lyocell, cotton sateen or synthetic satin
VerdictNot vegan
Where it hides
Scarves, ties and blouses labelled "100% silk" or "pure silk"
Bedding: pillowcases, duvet covers and eye masks
Sewing thread and embroidery floss
Sericin, the silk protein, in some cosmetics and hair products
Wild or "tussar" silk, a different species with the same killing step
What it is
A silkworm spends two to three days spinning a single filament, as much as 1,500 metres of it, into the cocoon meant to shelter it while it turns into a moth. Reeling that filament off in one unbroken length is what makes silk fabric possible, and it only works if the moth never gets the chance to break out. A United Nations manual for the industry explains the problem plainly:
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A newly emergent moth will pierce the shell rendering the cocoon useless for conversion to raw silk.
Cocoons are "stifled", the industry's own word, within days of being spun, before the moth can emerge. The same manual describes the fastest commercial method:
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Steam is rapid as pupae are killed within 30 minutes.
Sun drying and hot-air drying are the other two commercial methods, doing the same job by a slower route. "Peace silk" or "Ahimsa silk" is the one real variation: it waits for the moth to hatch and fly off before the empty, broken cocoon is reeled. It is a small and pricier share of the market, and it does not change the fact that the silkworms are still bred, confined and farmed for the fibre.
WoolWool is fibre sheared from a sheep's fleece, or combed from a goat for mohair and cashmere, and that is the fibre's legal definition. Shearing alone does not kill the sheep, but the wool trade runs on the same farms that supply the meat trade.
LeatherLeather is an animal's tanned skin or hide, almost always cattle, and US labelling rules say a product can only be called leather if it is made in all substantial parts of it. Plant and lab-grown alternatives exist, but they need a different name on the tag to be legal.
PearlsA pearl is layer upon layer of nacre that an oyster or mussel secretes around an irritant inside its own body, and almost every pearl sold today is cultured: a technician plants that irritant on purpose. Harvesting the pearl often kills the mollusc outright.
Frequently asked
How many silkworms does it take to make silk?
A great many: it takes several thousand cocoons to produce a single kilogram of raw silk, and the standard process kills the pupa in essentially every one of them.
Is peace silk vegan?
Most vegans still say no. The moth is allowed to live, but the silkworms are bred, confined and farmed specifically to be harvested from, the same objection vegans raise to other animal fibres even where no individual animal dies in the process.
What can replace silk?
Tencel (lyocell) and cupro, both spun from wood pulp, get closest to silk's drape and sheen. Polyester satin is the cheap, widely available stand-in, and cotton sateen is a breathable, low-cost choice for bedding.
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