Where Does Silk Come From: From the Silkworm to the Sleep Mask

Silk comes from a worm, or more precisely a caterpillar: the bombyx mori, the domesticated silkworm, which secretes a single continuous thread to spin its cocoon before turning into a moth. It is this thread, unwound and then spun, that becomes one of the most beautiful materials humankind has ever woven. Behind the softness of a scarf or a sleep mask lies a small, unassuming creature, one particular tree, and a story stretching back several thousand years, one that connected ancient China to the West long before the word "globalisation" was ever spoken.

Let us follow that journey, from cocoon to thread, and then from thread to the 22 momme mulberry silk we use today. It is a subject where biology, history and a little legend answer one another, and where we discover along the way why so many things sold as "silk" are nothing of the sort.

The bombyx mori, domesticated for thousands of years

The bombyx mori is an almost unique case in the living world: an insect so thoroughly domesticated that it can no longer survive on its own in the wild. Thousands of years of breeding have made it entirely dependent on human care, unable to truly fly, and whose only purpose, from the breeder's point of view, lies in the thread it produces.

This worm eats one thing, and one thing only, or nearly so: the leaves of the white mulberry, Morus alba. It is from this tree that "mulberry silk" takes its name. This is no marketing flourish but a fact of breeding: a caterpillar fed exclusively on mulberry leaves produces a particularly fine, white and even silk, whereas wild worms feeding on other foliage yield shorter, coarser and often beige fibres.

The bombyx life cycle is short and entirely geared towards this production. From the egg hatches a tiny caterpillar which, for about a month, does nothing but eat and grow, shedding its skin several times and multiplying its weight dramatically. Then comes the decisive moment: once mature, the caterpillar stops feeding and begins to secrete its thread, wrapping itself in a cocoon. Inside, it becomes a chrysalis, before emerging as a moth that will live only a few days and will not even feed. Almost all the energy of its short life has been invested in the cocoon.

From cocoon to thread: the craft of sericulture

The bombyx cocoon is a small marvel of natural engineering. The caterpillar does not weave it from many strands: it secretes a single, continuous filament, which it winds around itself in figure-of-eight movements for hours on end. Made mainly of two proteins, fibroin for the fibre and sericin for the glue that holds it together, this filament can reach several hundred metres in length without ever breaking. This continuity is what makes silk so valuable: unlike cotton or wool, made of short fibres that must be spun end to end, silk offers a thread that is already almost endless.

Sericulture is the art of raising these worms and harvesting their thread. To unwind the cocoon in one piece, it is placed in hot water, which dissolves some of the sericin and makes it possible to find the end of the filament and gently unroll it. Several of these filaments, too fine to be used alone, are combined to form a usable silk thread. It takes a great many cocoons, several hundred, to make a single piece of fabric such as a scarf or a mask: every silk object thus represents an amount of work, animal and human, that we rarely suspect when we hold it in our hands.

One point deserves to be stated plainly, because it comes up often: in the traditional process, the cocoon is treated while the chrysalis is still inside. We return to this further down, because it is a genuine question, and to skirt around it would be dishonest.

Why mulberry silk rather than any other

Not all silks are equal, and the main distinction begins with the worm's diet. So-called "mulberry" silk comes from the bombyx mori fed on mulberry leaves in controlled breeding. It is the finest, smoothest and most uniform of silks, with that pearly sheen and natural whiteness that make it instantly recognisable. Wild silks, such as tussah, come from other moths living freely and feeding on other foliage: their fibre is coarser, darker, with a more rustic charm.

That leaves a question buyers quite reasonably ask: what does that "22 momme" printed on quality products actually mean? The momme is a unit of weight of Japanese origin, used to measure the density of a silk fabric. The higher the number, the denser, heavier and more durable the fabric. A low-momme silk is light and slightly translucent; a high-momme silk is more opaque, softer to the touch and better able to last. 22 momme represents a sought-after balance for pieces meant to touch the skin: dense enough to offer real substance and fine longevity, without becoming stiff. This is the weight we chose for the Noctyā mask, precisely because it lasts over time while remaining wonderfully soft against the skin.

On that contact, we should stay factual. Mulberry silk has a naturally smooth surface, which helps limit friction on skin and hair. The fibre absorbs little moisture and has thermoregulating qualities that make it feel cool in summer and gentle in winter. These are material properties, pleasant and real, that it would be an exaggeration to turn into medical promises: a beautiful fabric remains a beautiful fabric, and that is already a great deal.

Satin, silk: clearing up the confusion for good

Here is the industry's most stubborn misunderstanding, and it is worth pausing on. Many people believe they are buying silk when they buy satin, and vice versa. Yet these two words do not describe the same thing, and are not even comparable.

Silk is a material, a natural fibre produced by the silkworm. Satin, on the other hand, is not a material: it is a type of weave, a way of interlacing threads to obtain a surface that is smooth and glossy on one side, more matte on the other. You can weave silk in satin, but also polyester, cotton or nylon. In other words, a "satin pillowcase" or a "satin mask" is very often a polyester piece woven in a satin weave, imitating the sheen of silk without any of its qualities: neither the breathability, nor the thermoregulation, nor the fineness of the natural fibre.

The confusion is maintained, whether deliberately or not, because it is commercially convenient: polyester satin costs a fraction of the price of silk and shines just as brightly under a studio light. The useful reflex, when buying, is therefore simple: do not read only the word "satin" or the glossy look, but look for the composition. "100% silk" is information about the material; "satin" is not.

From the Silk Road to the sleep mask

The story of silk is inseparable from that of ancient China, where its production has been documented for thousands of years. A legend, which must be presented as such, attributes its discovery to the empress Leizu, sometimes called Xiling: she is said to have watched a cocoon fall into her cup of hot tea and, trying to fish it out, to have unwound the first silk thread in history. Charming and no doubt embellished over the centuries, this story tells a deeper truth: China kept the secret of sericulture for a very long time, guarding it as a jealously protected monopoly.

That secret fuelled one of the greatest commercial adventures in human history. The Silk Road, that network of caravan routes linking China to the Mediterranean, owes its name to a material so precious it served almost as currency. Along these routes travelled not only bales of cloth but also ideas, religions and techniques, until silkworm breeding eventually spread to Central Asia, the Middle East, then Europe, and notably the Lyon region, long France's capital of silk.

It is the distant legacy of this journey that we still find today in something as simple as a sleep mask. To choose mulberry silk for sleeping is not merely to choose a soft material: it is to continue, on a modest scale, a craft that has crossed continents and centuries. The Noctyā mask sits within that continuity, with a deliberate preference for a noble material worked simply, for what it truly is.

FAQ: your questions about silk and the silkworm

How long does a silkworm live?

The full cycle of the bombyx mori is short, on the order of a few weeks. The caterpillar spends about a month feeding on mulberry leaves before spinning its cocoon. The moth that emerges lives only a few days and does not feed: its sole function is to reproduce.

Why mulberry silk rather than another silk?

Because the bombyx mori fed exclusively on mulberry leaves produces the finest, whitest and most even silk. Wild silks, from other moths, yield shorter and more irregular fibres with a more rustic finish.

What does "22 momme" mean?

The momme is a Japanese unit that measures the density of a silk fabric. The higher the number, the denser and more durable the fabric. 22 momme is a sought-after weight for pieces in contact with the skin: dense enough to last well over time, while staying supple and soft.

Is silk ethical or vegan?

No, silk is not vegan. In the traditional process, the cocoon is treated while the chrysalis is still inside, in order to preserve the continuous thread. There are so-called "peace silks" (ahimsa silk), which let the moth emerge before the cocoon is harvested, but the resulting thread is then broken up and of a different quality. It is a genuine question, and everyone deserves an honest answer in order to decide with full awareness.

What is the difference between silk and satin?

Silk is a material, a natural fibre. Satin is a weave, that is, a way of interlacing threads. You can weave satin in silk, but also in polyester or cotton. A "satin" product is therefore not necessarily silk: you should always check the composition.

How do you care for a silk item?

Silk likes gentleness: hand washing in cold water with a suitable soap, or a delicate cycle in a mesh bag, without vigorous wringing. Dry it flat, in the shade, away from direct heat. Well cared for, a fine mulberry silk will last for many years.