Mulberry Silk: How It Is Actually Made, and Why 19 Momme Is the Floor

Silk is the only textile fibre in common use that is produced by an animal as a continuous filament. Everything else — cotton, flax, wool, modal — arrives as short or medium fibres that have to be spun together. That single structural difference is behind almost everything people like about silk, and it starts with a tree.

How mulberry silk is actually made

The process, sericulture, has barely changed in principle for four thousand years:

1. The tree. White mulberry is planted and coppiced for its leaves. It is hardy, grows quickly, tolerates poor and marginal soil, and needs comparatively little water and few inputs — it is a genuinely undemanding crop.
2. The diet. Bombyx mori larvae are fed exclusively on mulberry leaves. That single-food diet is precisely why mulberry silk is so uniform: the fibre it produces is consistent, round, and a natural bright white. Wild silks, from moths that eat mixed foliage, produce coarser, irregular, naturally coloured fibre — beautiful, but not the same material.
3. The cocoon. Each larva spins a cocoon from one unbroken filament that can run to a kilometre or more.
4. Reeling. Several filaments are unwound together and combined into a single thread. Because the filament is continuous, there are almost no fibre ends at the surface — which is why silk is smooth, lustrous, and does not pill the way spun fibres do.

Long-staple cotton is prized because its fibres are a few centimetres long instead of one. Silk's are effectively endless. That is the whole difference.

The environmental picture, honestly

Silk's footprint is genuinely mixed, and it is worth setting out both halves.

In its favour: the mulberry tree is perennial, so the land is not ploughed and replanted annually the way a cotton or flax field is; it grows on marginal ground that would not support a food crop; it needs modest water and few chemical inputs; and sericulture is labour-intensive rather than machinery-intensive, which keeps energy use low and supports rural employment.

Against it: conventional silk reeling requires the cocoon to be treated before the moth emerges, because a moth chewing its way out breaks the continuous filament. That is a real ethical consideration and we are not going to skate past it. The alternative — peace or ahimsa silk, reeled from cocoons the moth has already left — produces short, broken fibres that must be spun, giving a fabric that is duller, fuzzier and considerably less durable. It is a genuine trade-off between two things people care about, not a solved problem.

The point where silk wins outright is lifespan. A well-made silk set, cared for properly, outlives almost anything else in a wardrobe. Because keeping a garment longer is by far the biggest lever anyone has on its footprint, a silk set worn for a decade compares extremely well against a cheaper fabric replaced four times over the same period.

Why 19 momme is our floor

Silk is measured in momme — a weight unit rather than a thread count. Higher momme means a denser, heavier, longer-lasting cloth.

• 12–16 momme — thin. Common in "affordable silk" listings, appropriate for scarves and linings, too fragile for sleepwear that gets washed. It goes sheer at stress points and shows wear within a season.
• 19 momme — the industry standard for quality silk sleepwear and pillowcases. Dense enough to be opaque and to survive regular washing, light enough to drape. Ours runs from the White Zebra long set and the Black Roses long set through to the solid nightshirts and bath robes.
• 22 momme — noticeably heavier, with better drape and a longer life again. The premium tier, and the weight we reserve for the Cream and Black Cockatoos sets.

Everything we sell in silk is 19 momme or 22 momme. We do not stock anything below that, because a 12 momme set is a bad purchase dressed up as a bargain — it costs less, wears out in a fraction of the time, and gives silk a reputation for fragility that a properly made piece does not deserve.

What silk actually does for you at night

• Cool on contact. Silk conducts heat away from the skin quickly on first touch. That is a different property from breathability, and it is the sensation people mean when they say a silk bed feels cool.
• Low friction. A smooth continuous filament creates less drag against skin and hair than a spun fibre with a textured surface — the practical reason a 19 momme eye mask sits differently against the face than a cotton one.
• Genuinely breathable. Silk is a protein fibre and absorbs moisture readily, so it does not go clammy the way a synthetic satin does. "Satin" is a weave, not a fibre — polyester satin looks similar and behaves nothing alike.

The care trade-off, stated plainly

Silk is the least convenient fabric we sell. Hand wash or a delicate cycle in a mesh bag, cool water, pH-neutral detergent, no biological powder — the enzymes in biological detergent digest protein, and silk is a protein. Never tumble dry, never wring, dry away from direct sun.

That is a real commitment, and it is why we do not recommend silk as an everyday, wash-twice-a-week set for most people. Modal Cloud is the fabric for the other 350 nights. Silk is for the nights you want it to be silk — and, treated properly, it will still be doing that in ten years.

Browse the silk sleepwear range, or read what momme means in more detail.