Silk Pillowcases: What Momme Means and Whether They're Worth It

Momme (pronounced “mommy”) is the weight of silk: the pounds a piece 45 inches wide and 100 yards long would weigh. A higher momme number means denser silk, which is generally more durable. Silk feels smooth and cool, but evidence that it improves skin or hair is still thin.

What does momme mean on a silk pillowcase?

Momme (written “mm”) is a traditional unit for silk fabric. Dharma Trading, a U.S. textile supplier, defines it as the weight in pounds of a piece of material 45 inches by 100 yards.

Working from that definition, one momme equals about 4.34 grams per square meter. So 19 momme is roughly 82 g/m², 22 momme about 95 g/m² and 25 momme about 108 g/m². Our arithmetic, not a label figure.

Momme runs across a wide range. Silk gauze can be as light as 3 to 5 momme, and heavy silk noil reaches 35 to 40.

19 vs 22 vs 25 momme

Dharma Trading groups silk into three bands. Under 20 momme is lightweight, used for summer scarves and linings. From 20 to 28 momme is medium weight, used for furnishings and bedding. Above 28 is heavyweight, used for curtains and outerwear.

Dharma Trading adds one caution: a higher-momme silk is heavier and denser but not necessarily thicker. Treat momme as a durability guide, not a softness score.

What about “6A grade” and “mulberry”?

Mulberry silk comes from the domestic silk moth Bombyx mori, whose caterpillars prefer white mulberry leaves. It is a primary source of the world’s silk.

Grades such as “6A” describe the quality of the raw fiber. Slip, for example, describes its pillowcases as 22 momme, 6A grade, long-fiber, 100% pure mulberry silk. Treat a grade as the seller’s own description of its fiber.

Are silk pillowcases worth it for hair and skin?

Here is what the evidence does and does not show.

Friction. Silk is smoother than cotton. Slip reports its silk creates 43 percent less friction than cotton, based on its own study, and adds that individual results vary. That is a manufacturer claim, not independent research.

Acne. No published trial has shown that silk pillowcases improve acne. A double-blind trial comparing 100% mulberry silk with 100% cotton pillowcases in 48 people with mild to moderate acne was registered on ClinicalTrials.gov in 2023. When we checked, no results were posted.

Eczema. A large trial of silk worn against the skin found no benefit. The CLOTHES trial gave 300 children with moderate to severe eczema silk garments for six months. Its authors concluded that silk clothing is unlikely to add benefit over standard care. That trial studied clothing, not pillowcases, but it is a useful reality check.

Wrinkles and hair loss. We found no published trial supporting these claims for silk pillowcases.

So a silk pillowcase is a comfort purchase. Many people simply like its cool, smooth feel. It is not a treatment for any skin or scalp condition.

How to wash a silk pillowcase

Silk does not like heat. These steps come from the care instructions published by Slip, a silk pillowcase maker.

1. Hand wash in water no warmer than 30°C (86°F) with a gentle pH-neutral liquid detergent. Slip calls this the best option.
2. Or machine wash on a delicate setting in cool water, max 30°C (86°F), inside a mesh delicates bag.
3. Air dry in the shade. Do not tumble dry.
4. Iron or steam on low heat if needed.

The mesh bag protects the silk from zips and hooks on other laundry.

How to buy a silk pillowcase

• Check the fiber content. It should say 100% silk or 100% mulberry silk. “Satin” or “silky” often means polyester.
• Look for a momme number. Without one, you cannot compare weight between listings.
• Match the closure to your pillow. Envelope closures have no hardware; zippers hold the pillow more firmly.
• Measure your pillow. Standard, queen and king pillowcases differ in length.

Related guides

A silk pillowcase pairs well with warm bedding. See our flannel sheets guide for cold nights, the cozy gift guide for present ideas, and how to make a room feel cozy for the rest of the bedroom. Our throw blanket buying guide covers the sofa side of things, and what weight of weighted blanket to get helps if you are adding one to the bed.