How to Tell if Silk Is Real: A 60-Second Test
You can usually tell in under a minute, with nothing but your eyes and hands. Real silk lists its momme weight and says "100% mulberry silk" on the label; it has a soft sheen that shifts colour as you turn it; it warms to your touch almost at once; and a burnt thread smells of singed hair, not chemicals. Polyester fails all four.
A lot of what gets sold as "silk" has never been near a silkworm. Polyester satin is cheap, shiny and easy to label loosely. So if you've ever wondered whether the pillowcase you bought is the real thing, it's a fair question, and here's how to settle it without any special equipment.
Start with the label and the price
The fastest checks happen before you even touch the fabric. Look for the word momme, the measure of silk's weight and density, which real silk always lists and polyester never mentions; good bedding silk sits around 19 to 25 momme. Look, too, for the words "100% mulberry silk" and an OEKO-TEX certification, which tells you the fabric has been tested for harmful substances. Then weigh up the price: if a "silk" pillowcase costs less than a takeaway dinner, under about $15, it's almost certainly polyester satin. Real silk simply costs more to make.
The sheen test
Hold the fabric up to the light and turn it slowly. Real silk has a gentle sheen that shifts colour as the angle changes, almost as if it glows from within. Polyester shines the same hard, flat way from every angle. Once you've seen the two side by side, you can't unsee it.
The feel and warmth test
Run it through your hands. Silk is smooth but not slippery, and here's the giveaway: it warms to your skin almost at once. Polyester stays cool and faintly plasticky no matter how long you hold it. Silk is a protein fibre, close in make-up to your own skin and hair, so it behaves like something alive rather than something extruded.
The burn test, for the truly unsure
If you have a spare thread and a careful hand, the burn test is the old tailor's trick, and it's conclusive. Real silk burns slowly, smells like singed hair, and leaves a brittle ash you can crush to powder. Polyester shrinks away from the flame, melts into a hard bead, and smells chemical. Only ever try this on a loose thread, over a sink and well away from the rest of the fabric and anything flammable. It settles the question for good, but there's no undoing it.
Reading the tag, specifically
The label is where most fakes quietly give themselves away. "100% silk" or "100% mulberry silk" is what you want to see. "Satin" on its own describes a weave, not a fibre, and is usually polyester. "Silk touch", "silky", "art silk" (short for artificial silk) and "satin silk" are all polite ways of saying not silk. When in doubt, the missing momme number is the tell.
But I saw a $10 "silk" pillowcase that felt just as good. Is it?
Almost certainly not, because "feels as good" in the shop and "is as good" after six months against your skin are two very different claims. A beauty writer for The Independent recently made headlines with a £7.28 pillowcase she swore felt as premium as her £80 Slip and Blissy favourites, and she may well be right about that first touch. Here's the catch: at that price, it isn't silk. Satin is a weave, not a fibre, and a cheap "silk satin" is almost always polyester: gorgeously slippery for a fortnight, then quietly pilling and flattening in the wash. The real difference is the one your hands can't feel on day one. Silk is a protein fibre that breathes and holds a little moisture, so it stays cool and dry against your face; polyester traps heat and moisture, which is the last thing warm or blemish-prone skin wants, and the very reason dermatologists tend to reach for silk. They'll happily admit the hard evidence is mostly anecdotal rather than trial-tested, so the honest case for the real thing isn't a miracle cure. It's simpler than that: real silk is smooth and breathable and still going strong years later, where the dupe has long since gone to the rag drawer. For where that price actually goes, see why silk costs what it does.
What this means when you shop
None of this is about snobbery. Real silk earns its price because it breathes, regulates temperature, and is gentle on skin and hair in a way polyester can't match, so if you're paying for those benefits, it's worth knowing you're actually getting them. For the fuller comparison, see how silk stacks up against polyester and satin, and what silk momme really tells you.
If you'd rather skip the detective work, our LS Silk NZ pillowcases are 100% mulberry silk, 22 momme and OEKO-TEX certified, with the momme stated on every product. Nothing to squint at on the label.
The funny thing is that once you've handled the real thing, felt it warm under your fingers and watched the light move through it, the fakes stop being convincing at all. Your hands learn the difference faster than your eyes do, and after that, you'll never quite be fooled again.