Mulberry Silk & Momme, Explained

If you’ve shopped for silk anything, you’ve seen two bits of jargon: mulberry and momme. Both get thrown around by marketing copy that assumes you already know what they mean. Here’s what they actually mean, how much they should influence your purchase, and which numbers to look for when comparing masks.

What is mulberry silk?

Mulberry silk is silk produced by Bombyx mori silkworms fed exclusively on mulberry leaves. That controlled diet — as opposed to the varied diet of wild silkworms — yields a fiber that’s longer, rounder in cross-section, and more uniform in color and texture than any other commercially available silk.

The comparison to wild or “tussah” silk (produced by silkworms feeding on oak or other leaves) is significant. Tussah silk is coarser, more textured, and has a naturally brownish cast. It’s used in rustic or artisanal textiles and is perfectly good silk — just different. For sleep masks, where smoothness and uniformity matter for skin contact and light blocking, mulberry silk is the correct choice.

When a mask claims “100% mulberry silk,” it’s claiming this specific fiber source. When a listing says only “silk” or “silky” without specifying mulberry, it may be tussah, a blend, or polyester satin marketed with vague terminology. Always check for “mulberry” specifically.

What does momme mean?

Momme (abbreviated mm, pronounced moh-mee) is a weight measurement with Japanese textile origins. Technically, it measures the weight in pounds of a piece of silk that is 45 inches wide and 100 yards long. In practice, momme tells you how much silk is in the fabric per unit area — a higher number means more silk threads packed into the weave, resulting in a denser, heavier, more opaque fabric.

The easiest analogy is thread count in cotton: just as a higher thread count means more cotton per square inch, a higher momme means more silk per square meter. And just as 600-thread-count sheets feel denser and more substantial than 200-thread-count ones, 22-momme silk feels meaningfully different from 16-momme silk in hand.

For sleep masks specifically, momme affects three things:

Opacity and light blocking — a denser weave transmits less light. A 22-momme mask blocks more light than a 19-momme flat mask of identical shape.

Durability — more silk per unit area means more fiber to absorb the stress of repeated washing and nightly use. A 22-momme mask will typically outlast a 19-momme mask by 12–24 months under identical care.

Feel — 22-momme silk has more substance in hand and a slightly more cushioned feel against the face. Some people prefer the lighter drape of 19-momme; others prefer the denser feel of 22.

Momme weights in context

Here’s how the common momme weights translate to real mask performance:

16 momme and below — lighter than ideal for daily mask use. Found in some budget masks and lightweight silk accessories. The silk is genuine but thin, and durability is limited.

19 momme — the everyday standard and the most common weight for silk sleep masks. This is where top sellers like the Alaska Bear and BeeVines 2-Pack sit. It’s soft, breathable, comfortable, and durable enough for 12–18 months of nightly use with proper care. For most buyers, this is the correct choice.

22 momme — the premium tier for sleep masks. Noticeably denser in hand, better at blocking light, and significantly more durable (2–4 years with care). Masks at this weight include the Blissy, ZIMASILK, Umisleep, LitBear, and Slip Contour. Worth the premium if you’re buying a mask you expect to use for years.

25 momme and above — primarily used for silk bedding and pillowcases. The additional density offers minimal benefit in a sleep mask application and significantly increases the price.

What about grade 6A?

Alongside momme, some listings advertise a “grade” — most commonly 6A. This grades the quality of the silk filaments: their length, uniformity, and freedom from defects. The scale runs from 1A (lowest) to 6A (highest).

Grade 6A indicates the longest, most uniform filaments with the least variation — the kind that produce the smoothest, most consistent woven fabric and best hold up through repeated washing.

The important caveat: silk grading is not independently certified. It’s self-reported by suppliers and manufacturers. There’s no international third party auditing whether a mask labeled “6A” actually meets that standard. This doesn’t mean the label is meaningless — reputable brands like Blissy that stake their reputation on material quality have an incentive to be accurate — but it means “grade 6A” is a claim to evaluate alongside other evidence, not a guaranteed specification.

In practice: when you see 22-momme, grade-6A mulberry silk from a brand with a track record, you’re likely getting excellent silk. When you see the same labels from an unknown brand with no reviews and a suspiciously low price, treat it with skepticism.

How to spot fake silk before you buy

Check the fiber content. The listing should say “100% mulberry silk” explicitly, not “silk feel,” “charmeuse,” “satin,” or just “100% silk” without the mulberry qualifier.

Check the momme. Genuine silk listings for masks typically specify 19 or 22 momme. Listings that don’t specify momme either don’t know (budget wholesale product) or are hiding that it’s synthetic.

Check the certifications. OEKO-TEX certification is independently verified and means the silk and dyes have been tested and confirmed free of harmful chemicals. Several reputable brands (Blissy, among others) carry this.

Check the price. Genuine 19-momme mulberry silk masks start around $12–15. Anything marketed as “real mulberry silk” below that threshold is likely synthetic or misrepresented.

The burn test (for fabric you already own): hold a thread to a flame. Real silk smells like burning hair and self-extinguishes when the flame is removed. Polyester melts, produces a chemical smell, and leaves a hard plastic bead.

The practical takeaway

You don’t need to memorize any of this to buy well. The simplified rule: look for 100% mulberry silk, 19–22 momme, from a brand that specifies both clearly. That covers 90% of what you need to evaluate any mask on material quality.

For how momme and other factors combine into an actual buying recommendation, see the how to choose a silk sleep mask guide or jump straight to the full roundup.