Silk, by the momme

Silk is sold by a unit almost no one has heard of, and on a fiber few people have seen up close. Learn three words and you'll shop it with confidence.

Mulberry

Most fine silk is mulberry silk, spun by the domesticated Bombyx mori silkworm, which is raised on a diet of mulberry leaves. Because the cocoons are reeled whole, the result is a very long, continuous filament. That makes silk smooth and strong and gives it its characteristic luster. "Wild" and "tussah" silks are shorter, slubbier, and more textured. They're beautiful, but they're a different material.

Momme

Momme (mm) is a Japanese unit of weight, and for silk it plays the role thread count plays for cotton. Higher momme means more silk in every square inch: heavier, more opaque, and more durable.

• 12–16 momme: scarves and linings. Light and floaty.
• 19 momme: a classic weight for good sleepwear and blouses.
• 22–25 momme: pillowcases and bedding. Substantial, and it survives frequent washing.
• 30 momme: rare and luxurious, with a heavy, liquid drape.

A silk pillowcase under 19 momme will wear thin quickly. Brands that don't state the momme often have a reason not to.

Weave and finish

• Charmeuse: the glossy face with a matte back that most people picture when they think of silk.
• Crepe de chine: a matte, slightly pebbled weave that's lightweight and very wearable.
• Sandwashed: silk tumbled until the surface turns soft and suede-like with a quiet sheen. It's easier to wear and less precious.
• Washable silk: silk treated so it can go in a gentle machine cycle. It's a useful category, as long as the fiber underneath is good.

Living with it

Wash silk cool with a pH-neutral detergent, skip the fabric softener, and dry it out of direct sun. Press it on low heat with a cloth between the iron and the silk. Good silk, properly weighted, isn't fragile. It's simply particular.