Updated October 31, 2026 · By Momiel
Short answer: on a silk pillowcase, a hidden zipper keeps the pillow fully enclosed and the case smooth, while an envelope closure (a fold-over flap) has no hardware but can work loose, because silk is slippery. If you move a lot in your sleep or want a neat, tailored look, choose a zipper. If you want the simplest construction with nothing to snag, an envelope is fine.
How does an envelope closure work?
An envelope pillowcase has an extra panel of fabric sewn inside the open end. You tuck the end of the pillow under that flap, and the flap holds it in place. There is no zipper, button or snap.
- Pros: no hardware, nothing to break, easy to sew, quick to put on.
- Cons: on smooth fabrics like silk the pillow can slide out from under the flap overnight, and the flap adds a fold you can feel at one end.
How does a hidden zipper closure work?
A hidden zipper runs along one short side of the case, under a fold of fabric so the teeth don't touch your face. You open it, slide the pillow in and close it.
- Pros: the pillow can't slip out, the case lies flat, both sides look the same.
- Cons: there is hardware to look after. Close the zipper before washing so the teeth don't catch the silk.
Side-by-side comparison
| Envelope | Hidden zipper | |
|---|---|---|
| Keeps pillow in place on silk | Can loosen | Yes |
| Hardware | None | Zipper |
| Washing | Simple | Close zipper, use a mesh bag |
| Look on the bed | Flap visible on one side | Smooth both sides |
Which closure does Momiel use?
Our 22 momme silk pillowcase uses a hidden side zipper, not an envelope flap. It is 100% mulberry silk in Standard (20 × 26 in, $55) and Queen (20 × 30 in, $59), in six colors. If you're unsure which size to choose, see our pillowcase size guide.
FAQ
Will I feel the zipper when I sleep?
The zipper sits along the short side under a fabric fold, at the end of the pillow, away from where your face usually rests.
How do I wash a zippered silk pillowcase?
Close the zipper, turn the case inside out, and hand wash or machine wash cold in a mesh bag with a pH-neutral silk detergent. Full steps: how to wash a silk pillowcase.
Can an envelope silk pillowcase be good?
Yes. Closure is a preference. Check the fibre (100% silk) and momme weight first; those matter more than the closure.
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