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The Shortlist
Slip did more than any other company to turn the silk pillowcase from a curiosity into a beauty staple. Its cases are sold in department stores, photographed on well-made beds and priced like a luxury skincare product. For curly hair, the claim is simple: less friction overnight means less frizz, fewer tangles and curls that last longer between washes.
The claim is reasonable. Whether it requires this particular pillowcase is a separate question.
What it is
The Slip pillowcase is made from long-fiber mulberry silk at a weight of 22 momme. Momme is the measure of silk density, in the way thread count is for cotton. Most silk bedding falls between 19 and 25; at 22, Slip's fabric is thick enough to last and still drapes softly.
The finish is what the brand is known for. The fabric is smooth and heavy, the stitching is neat and the colors are rich.
Silk and satin are different things
This is the most common confusion in the category.
- Silk is a fiber, spun by silkworms. It is a natural protein, breathable and good at regulating temperature.
- Satin is a weave, a way of arranging threads to produce a glossy surface. Most satin pillowcases and bonnets are woven from polyester.
Both are smooth. Both let hair glide instead of catching. The differences lie in how they feel and how they wear: silk breathes and feels cooler, while polyester satin can feel warm and slippery, and tends to cost a fraction of the price.
What it does for curls
A cotton pillowcase has a slightly rough surface and absorbs moisture. Over a night of turning, it roughens the cuticle, pulls curl clumps apart and takes some of your leave-in with it.
A silk or satin surface reduces that friction considerably and absorbs less. In practice, people who switch tend to report:
- Less frizz on waking, particularly at the back of the head.
- Fewer tangles and knots at the nape.
- Curls that keep their definition for an extra day.
It is worth being clear about the evidence. The reasoning is sound and the reports are consistent, but there is little independent clinical research comparing pillowcase fabrics. Claims that go further, such as silk preventing hair loss or split ends, should be treated with caution.
The benefit comes from smoothness. Silk is one way to buy it, and not the cheapest.
The case for Slip
- Quality. Dense, consistent silk that holds up to years of washing if treated properly.
- Comfort. Silk is cooler than polyester satin, which matters if you sleep warm.
- It covers the bonnet-averse. A pillowcase protects your hair with nothing on your head, and on the nights a bonnet slips off.
- Skin. Many buyers choose silk as much for their face as their hair.
The case against
- Price. It costs several times what a satin pillowcase does, and noticeably more than other 22-momme silk cases.
- Care. Silk should be washed gently, in cool water with a mild detergent, and air dried. A satin case goes in with the rest of the laundry.
- A bonnet does more. A pillowcase reduces friction. A bonnet also keeps curls contained and in shape, for much less money.
The alternatives
The verdict
For curly hair alone, the Slip pillowcase is a luxury, not a necessity. A satin pillowcase or a good bonnet protects curls nearly as well for far less. What Slip offers beyond that is comfort, breathability and the pleasure of a beautifully made object, and those are fair reasons to buy one if the price does not trouble you.
If you sleep hot, dislike polyester or refuse to wear a bonnet, it is a sound purchase. If you simply want better second-day curls, start with satin, and read The Second-Day Refresh.