Silk vs. satin pillowcases: the difference nobody explains

You've seen the listings: "luxury satin pillowcase, silky smooth, for hair and skin." Half the price of silk, looks exactly the same in the photo. So what's the catch?

The thing nobody tells you

Silk is a fiber. Satin is a weave. "Satin" just means the threads are woven so that one side comes out glossy. You can weave satin out of silk, but the satin pillowcases filling your feed are almost always polyester, which is, technically speaking, plastic.

So does it matter?

Both feel smooth, so both are kinder to your hair than rough cotton. The differences show up a few hours in, and a few washes in.

• Heat. Polyester doesn't breathe well. If you've ever woken up with a sweaty cheek on a satin pillowcase, that's why. Silk breathes and stays cooler.
• Feel. Satin is slippery in a slick, almost squeaky way. Silk is smooth in a softer, more fluid way. Once you've felt both, you can't unfeel it.
• Static. Polyester loves static, which is not what you want anywhere near freshly washed hair.
• Wash day. Synthetic fabrics shed tiny microfibers in the wash. Silk is a natural fiber.

On our nightstandThe Evevior silk pillowcaseOrganic 6A mulberry silk, 22 momme, in four colors named for Barbados.Take a look

Why satin costs less

Polyester comes off a factory line by the mile. Silk starts as silkworm cocoons, each one unwound into a single filament, then reeled, woven and finished by people who really know what they're doing. The price gap is the material, not the marketing.

Rule of thumb: if the word silk only shows up as an adjective, it isn't silk.

How to shop smarter

Ignore the product title and scroll straight to the fiber content. "Silky," "silk feel" and "satin silk" are all polite ways of saying polyester. Real silk says 100% silk, usually mulberry, and lists a momme weight. If you can't find the fiber content anywhere, that tells you something too.