How do I know if a "satin" pillowcase is really silk?

Look for the exact composition in the product description: it should say "100% silk" and ideally "mulberry silk." If only the word "satin" appears with no fiber mentioned, it's almost always polyester.

Is a polyester satin pillowcase completely useless?

No, it already offers less friction than a rough regular cotton and a lower price. But it doesn't bring the specific benefits (non-absorption, protein structure) that only real mulberry silk provides — it's a compromise, not an equivalent.

Silk or Satin?

Satin Pillowcase or Silk: The Difference Most Labels Don't Explain

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"Satin" Describes a Weave, not a Material

This is the most common marketing trap in this market: "satin" isn't a material, it's a weaving method — any fiber, including polyester or nylon, can be woven in a satin pattern to get that glossy look. The vast majority of cheap "satin" pillowcases are therefore actually tightly woven polyester, not silk.

Why This Confusion Costs Your Skin and Hair

A polyester satin pillowcase can shine like silk in a photo, but the fiber remains synthetic and absorbent: it pulls moisture from skin and catches hair overnight, exactly the opposite of what you're looking for. Only a pillowcase in real mulberry silk, satin-woven or not, has the non-absorbent protein structure that actually protects.

      "A "satin" pillowcase and a "silk" pillowcase can look exactly as glossy in a product photo. Only the fiber composition — not the weave — determines what skin and hair actually feel.
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Pillowcase Type	Actual Composition	Absorbs Moisture
Generic "Satin"	Polyester/nylon	Yes
Silk-Satin (blend)	Mixed fiber	Partially
Silkhouse Silk	100% mulberry silk	No

Check the Composition, Never Just the Name

The word "satin" on a label guarantees nothing about the material. Look for "100% mulberry silk" explicitly — it's the only reliable marker. Silkhouse pillowcases are Oeko-Tex certified, no ambiguity.