Silk Lingerie Grading: Momme Weight, 6A Mulberry Silk and Weave Densities

The short answer: two numbers get quoted on silk lingerie and sleepwear. Momme is fabric weight — how much silk there is per square metre — and higher generally means more opaque and more durable. Grade, such as "6A", describes the raw silk yarn before it was woven, measured by tests of evenness, cleanness and strength. Both are useful; neither tells you how well the garment was cut and sewn, and "6A" on a label is a claim you usually cannot check.

Genuine silk varies enormously between garments that are all, accurately, labelled "100% silk". A light, sheer slip and a heavy robe can both be pure silk and behave completely differently in wear and in the wash. The difference sits in a handful of specifications that are worth knowing how to read.

What momme means

Momme (abbreviated "mm") is a traditional Japanese unit of silk weight. One momme is roughly 4.3 grams of silk per square metre; sources differ slightly in the exact conversion — the French silk house Maison de la Soie gives 4.3056 g/m², while 4.340 g/m² is also widely quoted. Either way, 19 momme is a little over 80 grams of silk per square metre.

Momme is a better guide for silk than thread count. Maison de la Soie makes the point that two silk fabrics can have the same thread count without being the same quality; weight per area captures more of what you feel.

How the common weights tend to be used:

Maison de la Soie, for example, lists under 12 momme for scarves and light garments, 12 to 16 momme for silk pyjamas alongside heavier ranges, and recommends 19 momme for bed linen for durability. Heavier silk is generally more opaque and hard-wearing, and costs more because there is more silk in it — but a heavy fabric badly sewn is still a badly made garment.

What "6A" actually means

Grades like 6A come from testing raw silk yarn, not finished garments. India's government knowledge portal Vikaspedia describes the systems in its explainer on raw silk grading:

• China's system divides raw silk into 11 grades: 6A, 5A, 4A, 3A, 2A, A, B, C, D, E and F. It describes 5A and 6A as the top, representing under 10% of production.
• The grade comes from tests on the yarn: a seriplane test, in which inspectors grade wound yarn for evenness, cleanness (no major defects such as slubs or waste knots) and neatness (no fine hairiness or small loops); a serigraph test of tenacity and elongation; and measurements of size and how much it varies.
• Why it matters to a mill: lower-grade silk breaks more often on winding machines, and high-tenacity silk is needed for warp threads that carry tension on the loom.

Three practical conclusions follow. A grade describes the yarn a mill bought, not the cut, seams or finish of the garment. There is no grade "1A" — the top of the Chinese scale runs 6A, 5A, 4A, 3A, 2A, then A. And a retailer's "6A" claim usually comes without the test certificate that would back it, so treat it as a positive signal rather than a guarantee.

Weave: why two silks of the same weight feel different

Charmeuse is a satin weave: long floating threads on the face give a high, reflective sheen, and the back is matte. It is the classic lingerie silk.

Crêpe de Chine uses highly twisted yarns for a fine, pebbled, matte surface. It is less shiny than charmeuse and tends to show creases less.

Habotai (also spelt habutai) is a plain weave — a light, smooth silk often used for linings and light garments. It is a weave, not a lower grade.

Silk satin versus "satin". Satin is a weave, not a fibre. A label that says "satin" or "silky satin" without "silk" in the composition is usually polyester.

How to judge a silk garment

• Read the composition label. It should say silk, and ideally 100% silk for the face fabric. "Satin" alone describes the weave.
• Look for a stated momme. Serious silk sellers publish it; its absence is not proof of poor quality, but its presence lets you compare.
• Treat "6A" as a claim about the yarn. Welcome, unverifiable on its own, and silent about the sewing.
• Check the seams. Silk frays; enclosed seams such as French seams last better than raw overlocked edges on a fine fabric.
• Hold it to the light if opacity matters — lighter weights are translucent by nature.

Care matters as much as specification. Silk should be hand washed cool and never tumble dried — Agent Provocateur's own care guide says silk garments should never go in the washing machine or dryer. The full method is in how to wash and store luxury lingerie, and the wider fabric picture is in lingerie fabrics explained. Silk also takes dye differently from the elastic and trims around it, which is part of why some reds look uneven — covered in best red lingerie brands — and fabric choices across the luxury houses are in best luxury lingerie brands.

Sources quoted as read on 16 October 2026. Momme conversions and grading terms vary slightly between sources; where they differ, we say so.