What is mulberry silk? Meaning, grades, momme and uses

Mulberry silk is the silk spun by a single silkworm, Bombyx mori, fed exclusively on white mulberry leaves. Each cocoon yields one continuous thread of up to 900 metres, 10 to 24 micrometres in diameter, made of two proteins: 70–80% fibroin and 20–30% sericin, the gum removed during degumming — whereas wild tussah silk measures 50 to 70 micrometres and remains irregular. It comes almost entirely from Asia, with China producing about three quarters of the world's raw silk.

Mulberry silk: what exactly is it?

Mulberry silk refers to the silk spun by the Bombyx mori silkworm under controlled farming conditions. Each cocoon is made up of a single continuous thread that can measure up to 900 metres. This thread is then reeled, twisted, and woven to form the fabric.

What distinguishes mulberry silk from other natural silks is the silkworm's exclusive diet: the white mulberry leaf gives the fibre a particularly stable protein composition, with a smooth surface and natural white colour. The result: a more uniform, softer, and easier-to-dye fabric.

Mulberry silk vs wild silk: what's the difference?

Wild silk — also known as Tussah silk — is produced by silkworms living in the wild, feeding on oak or other leaves. This varied diet produces a more irregular, thicker fibre that is naturally beige or brown in colour.

In practice: wild silk is more rustic and less expensive. It suits certain garments or accessories. But for use in direct contact with skin — sleep mask, pillowcase, underwear — mulberry silk is clearly superior: softer, more uniform, less likely to create micro-friction.

Grade 6A: how to evaluate mulberry silk quality

Mulberry silk is classified by grade, from A to 6A. The grade evaluates several criteria: thread length, uniformity, lustre, and absence of impurities.

• Grade A: basic quality, short thread, less uniform
• Grade 3A / 4A: intermediate quality, common in standard textiles
• Grade 6A: maximum quality, long thread, very uniform, intense lustre — the standard for premium masks and pillowcases

Grade alone isn't enough to evaluate a silk: you also need to know the momme, which measures fabric density.

Momme: understanding silk density

Momme (abbreviated "mm" or "momme") is the weight unit used to measure silk density. The higher the momme, the denser, heavier, and more durable the fabric.

Momme	Typical use	Assessment
6 – 9	Fine scarves, linings	Too light for skin contact
12 – 16	Masks, lightweight garments	Acceptable, lacks body
19 – 22	Premium masks, pillowcases	Optimal balance of softness and structure
25 +	Bedding, silk duvets	Dense, luxurious, suited to large surfaces

22 momme silk is the recommended standard for a sleep mask or pillowcase: dense enough to last, supple enough to remain lightweight against the skin.

22 momme mulberry silk: why this choice for a sleep mask?

A 22 momme silk mask offers three concrete advantages over lighter silk:

1. Durability — 22 momme silk retains its softness and shape far longer than 12 to 16 momme silk, which wears and fades more quickly
2. Feel — denser, it has a fuller, more "refined" sensation against the skin of the face
3. Structure — the mask holds its shape better through washes and nights

Maison Noctya chose 22 momme mulberry silk for the Noctya sleep mask precisely for this balance: dense enough to last, light enough to be forgotten on the face.

Mulberry silk and hair: is it useful?

Mulberry silk is often cited in the haircare world. The principle: unlike cotton or synthetic satin, the smooth surface of natural silk reduces friction between hair and fabric during the night. Less friction means less breakage, less frizz, less dryness for treated or fragile hair.

It's for this same reason that mulberry silk pillowcases are favoured by people with curly, coloured, or fine hair. The benefit isn't dramatic overnight — it accumulates over time.

Mulberry silk fabric: common uses

Mulberry silk is used in many textile products:

• Sleep masks — direct contact with facial skin, gentle light blocking
• Pillowcases — reducing skin and hair friction during sleep
• Scarves and silk squares — lightness, sheen, natural drape
• Underwear and nightwear — thermoregulation, feeling of freshness
• Duvets and fillings — natural thermal insulation without heaviness

Mulberry silk price: what to expect

Mulberry silk is naturally more expensive than cotton or synthetic satin — production is artisanal, yields are limited, and the transformation chain is long. For a sleep mask, a price between €30 and €60 is consistent with 22 momme grade 6A mulberry silk. Below €15, the "silk" composition deserves closer inspection: it may be polyester satin or a blend.

Durability works in silk's favour: a well-maintained mask retains its softness for several years, whereas a cheap mask deteriorates within months.

How to care for mulberry silk

Caring for mulberry silk follows a few simple rules:

• Hand wash, cold water (max 30°C), mild sulphate-free soap
• No machine wash on normal cycle, no tumble dryer
• Dry flat, away from direct light
• No bleach, no enzymatic detergent

→ Complete guide: how to wash silk without damaging it

Frequently asked questions about mulberry silk

Is mulberry silk really better than other silks?

For use in direct skin contact (mask, pillowcase, nightwear), yes. Its uniformity, softness, and stable protein composition make it the reference. Wild silks are rougher and less suited to this type of use.

How to recognise genuine mulberry silk?

Check the composition listed on the label: "100% mulberry silk." The grade (ideally 6A) and momme (19 to 22 for a mask) should be specified. If this information is absent, be cautious.

Is mulberry silk ecological?

Silk is a natural, biodegradable fibre. Its ecological footprint is more nuanced than organic cotton: silkworm farming is intensive in water and heat, but the fibre lasts a long time when well cared for. Unlike synthetic satin (polyester), it does not release microplastics when washed.

Can mulberry silk be used for curly hair?

Yes. The smooth surface of silk reduces the friction that causes breakage and frizz, particularly at night. A mulberry silk pillowcase is especially useful for treated, coloured, or fragile hair.

The mulberry silk pillowcase: what changes compared to a sleep mask

A mulberry silk pillowcase is not a larger sleep mask. It receives the face, the hair, evening skincare and perspiration for seven to eight hours a night, and above all it is washed far more often.

That last point matters more than it sounds: silk loses up to 20% of its strength when wet. It is strong dry and vulnerable damp, which is where every care rule comes from — never wring, never rub, support the piece while wet, dry flat. On a pillowcase washed weekly, this becomes the main factor in how long it lasts.

One more mechanical detail: silk has moderate to poor elasticity. Stretched even slightly, it does not fully return. A pillowcase forced onto an over-sized pillow keeps that deformation permanently, which is why choosing the right size matters more on silk than on cotton.

What momme for a silk pillowcase?

Plainly: no standard defines a momme per product type. Momme is a Japanese weight unit, not a product specification. The only honest reference is what the market actually sells — recorded on Amazon.fr in July 2026, silk pillowcases are sold in 19, 20, 22 and 25 momme, with some bedding brands going up to 30.

A detail worth knowing: in bedding sets sold as a bundle, the weight varies from piece to piece. A duvet cover advertised at 25 momme is commonly paired with pillowcases at 20 momme under a single listing. One figure quoted for a whole set tells you nothing about the pillowcase itself — ask for the weight piece by piece.

Reading the label on a silk pillowcase

EU Regulation 1007/2011 governs textile labelling, and two points are useful when buying. "Silk" is a reserved fibre name (Article 5 and Annex I), and the text states these names may not be used for other fibres, even as an adjective. Meanwhile, the word "satin" does not appear once in the regulation: it is a weave, not a fibre, and it can be silk or polyester.

Two more checks. On 25 silk pillowcase listings recorded on Amazon.fr in July 2026, 15 displayed the momme — the rest did not. And an OEKO-TEX number can be verified online, but it certifies the absence of harmful substances, not that the fabric is silk. Confusing the two is the most common mistake.

→ Discover the Maison Noctya 22 momme mulberry silk sleep mask

Friction: why silk doesn't pull

Every fabric has a coefficient of friction — the resistance it offers when sliding against a surface. The higher it is, the more the fabric catches.

• Mulberry silk: 0.1 – 0.2
• Cotton: 0.4 – 0.6
• Synthetic: 0.5 – 0.7

You move 40 to 50 times in your sleep each night. At every movement, the skin-fabric friction plays out. With silk, it's nearly zero — the fabric follows. With cotton, it creates an imperceptible micro-resistance that, accumulated over 8 hours, disrupts light sleep phases and leaves traces on waking.

Protein structure: why natural fibres aren't all the same

Silk is a natural fibre composed of 70–80% fibroin — a structural protein made of continuous, smooth filaments. Unlike cotton fibres (twisted structure with microscopic irregularities) or synthetic fibres (surface irregularities visible under an electron microscope), fibroin creates a surface with no measurable roughness.

It's the same logic as the difference between a textured wall and a polished one: to the eye, the gap is subtle. In repeated contact with skin over hours, it's total.

Hygroscopicity: why silk doesn't overheat

Silk is hygroscopic: it absorbs up to 30% of its weight in moisture without feeling wet. It captures nocturnal micro-perspiration and disperses it into the air — instead of retaining it against the skin like saturated cotton, or blocking it entirely like synthetics.

The surface touching your skin stays dry. Perceived dryness creates the sensation of coolness. And coolness — not cold, coolness — is the sensory component most often associated with softness. Softness isn't just about texture: it's the simultaneous management of friction, moisture, and temperature.

This property is amplified by 22 momme fabric density — the optimal weight to maximise hygroscopicity without losing breathability.

Thermoregulation: a fabric that adapts to your skin

Silk is naturally thermoregulating. It adapts to the warmth of your skin rather than imposing its own temperature. No "hot" sensation on waking. No unpleasant "cold" at first touch.

This property comes from the fibroin structure and the way filaments trap air in microscopic layers — a mechanism similar to wool, but at a lightness incomparably finer. It's one of the reasons mulberry silk has been used for centuries in regions with extreme temperatures, in both summer and winter.

Static electricity: the invisible advantage

Silk generates no static electricity. The protein structure of fibroin naturally dissipates electrostatic charges. Polyester satin, on the other hand, generates them continuously — that's why a satin mask clings slightly to the face in the morning, why hair around it is disturbed, and why the fabric attracts fine particles overnight.

It's a discreet advantage. On facial skin, over 8 consecutive hours, it's not trivial.

Why silk is softer: the four simultaneous reasons

Not by chance. Not by marketing. Through the alignment of four physical properties that express themselves simultaneously: low friction, smooth structure, high hygroscopicity, natural thermoregulation. No synthetic fibre unites all four. No other natural fibre unites them as effectively for prolonged skin contact.

If you want to compare silk, cotton, and satin with numbers, the full comparison is here. And if you want to understand what 22 momme actually changes in fabric density, it's explained here. The Noctya Sleep Mask is made from 22 momme mulberry silk.