A pillowcase arrives, it is smooth and shiny, and the listing said silk. Still, something makes you wonder. Polyester satin can look very close to silk in a photo, and words like "silky" and "satin silk" are used loosely enough to confuse anyone.
You do not need a lab to get a good idea of what you are holding. These six checks go from the easiest to the most decisive.
The short answer: read the fiber content first. Real silk is labeled 100% silk or 100% mulberry silk and is sold by momme weight. It has a soft sheen that shifts with the light, it warms quickly in your hand, and a loose thread burns like hair, not like plastic.
1. Read the fiber content
This is the check that matters most, and it takes ten seconds. Look at the sewn-in label and the product page for the fiber content. It should say silk, and ideally mulberry silk, with a percentage.
Words that are not fiber content: satin, silky, silk feel, silk touch, vegan silk, art silk. Satin is a weave, not a fiber, and a pillowcase sold only as "satin" is almost always polyester. Our guide to the difference between silk and satin explains why the two get mixed up.
2. Look for the momme
Silk is sold by weight, and the unit is momme. A seller of real silk nearly always states it, because it is the main thing that separates one silk from another. Pillowcases and bedding usually fall somewhere between 19 and 25 momme.
Polyester has no momme. If a listing gives a thread count and no momme, or no weight at all, be careful. If you are not sure what the number means, read what momme is and how the weights compare.
3. Watch how it catches the light
Hold the fabric near a window and tilt it slowly. Silk has a soft, pearl-like sheen, and the tone seems to change a little as the angle changes. That comes from the shape of the fiber itself.
Polyester satin shines in a flatter, brighter way. It tends to look the same white gloss from every angle, a little like plastic wrap. This check is easier when you have a known polyester item next to it for comparison.
4. Feel it in your hand
Two things are worth noticing.
- Warmth. Bunch the fabric in your fist for a few seconds. Silk feels cool at first and then warms to your hand quickly. Polyester tends to stay cool and slick.
- Grip and sound. Silk is smooth, but it is not slippery in the way polyester is. Rub two layers together and silk has a slight, soft resistance. Heavier silk can make a faint crunching sound, something like walking on fresh snow.
Feel is a helpful sign, not proof. Some modern synthetics are made to feel very soft.
5. Check both sides, and the price
Turn the pillowcase over. Some are silk on the top face and polyester underneath, which is cheaper to make and easy to miss in a listing. The fiber content should cover the whole item. If the back looks duller or feels different from the front, read the label again.
Then look at the price with a clear head. Mulberry silk takes a lot of work to produce, and it cannot be sold for the price of a polyester pillowcase. A very low price is not proof of a fake, but it is a reason to check everything else twice.
6. The burn test, if you want to be sure
This is the classic test, and it is the most decisive one you can do at home. It also involves a flame, so do it carefully or skip it.
- Pull a single loose thread from an inside seam. Do not cut into the fabric.
- Hold the thread with metal tweezers over a sink or a ceramic dish, away from anything that can catch.
- Touch the end to a flame for a moment, then take it away.
| Real silk | Polyester | |
|---|---|---|
| How it burns | Slowly, and it tends to stop when the flame is removed | Melts and shrinks away from the flame, may keep burning |
| Smell | Like burnt hair | Chemical, like hot plastic |
| What is left | Dark ash that crushes to powder | A hard bead that does not crush |
Silk is a protein fiber, like hair, which is why it smells the same when it burns. The test cannot tell you the grade of the silk or whether it is mulberry, and a blended thread gives a mixed result.
Questions people ask
Does real silk wrinkle?
Yes. Silk creases when you scrunch it, and the creases soften again with a little steam or a night of use. Polyester satin resists wrinkles much more.
Is the ring test reliable?
Not really. Pulling fabric through a ring shows that it is thin and smooth. Light polyester passes it easily, and heavier real silk may not.
Can real silk be machine washed?
Often yes, on a cold, gentle cycle with a silk detergent, but that says nothing about whether it is real. Follow the care label.
At KINT the fiber content is the first thing we state. Our silk pillowcases are 100% mulberry silk, Grade 6A, with silk on both sides, in 19 or 22 momme. If you want the heavier weight, start with the Mulberry Silk Pillowcase 22 Momme.
