Before you buy, the listing tells you more than the fabric will. Real silk listings publish a momme weight and a fibre grade; imitations publish adjectives. After it arrives, the burn test on a single seam thread is the only reliable proof — real silk smells of burnt hair and crumbles to ash, while polyester melts into a hard bead.
We sell silk. We also sell satin, and we say so on the page. That is the position this article is written from.
The Words That Tell You It Is Not Silk
Most of the work happens before checkout. A listing that means silk names the fibre and its weight. A listing that means something else reaches for feeling words.
- "Satin" is a weave, not a fibre. Satin can be silk, polyester, nylon or acetate. On its own it tells you nothing about the material.
- "Silky", "silk-touch", "silk-like", "vegan silk" — all describe a sensation. None contain silk.
- "Charmeuse" is also a weave. Silk charmeuse exists; so does polyester charmeuse, and it is far more common.
- "Mulberry silk blend" with no percentage. A blend that will not name its ratio is usually mostly the cheaper half.
- No momme number anywhere. Any brand that has actually bought silk knows its momme. Omitting it is a choice.
What a Real Silk Listing Publishes
| Spec | What it means | What its absence suggests |
|---|---|---|
| Momme (mm) | Fabric weight — how much silk is physically in each square metre. 16 mm is light; 19 mm falls rather than floats | The seller either does not know or would rather you did not |
| Grade (6A, 5A…) | Fibre length and evenness in the sorted cocoons. 6A is the longest and most even | Common on genuine budget silk; universal on fakes |
| Fibre percentage | "100% mulberry silk" vs "silk blend, 12% silk" | A blend hiding its ratio |
| Weave density | Stitches per unit — how tightly the fabric is constructed | Almost nobody publishes it, in either direction |
| Care instruction | Real silk asks for cool water and no bleach | "Machine wash warm, tumble dry" on a "silk" item is a contradiction |
The last row is the quiet giveaway. Silk protein degrades in heat and alkali. A garment whose own care label says warm machine wash and tumble dry is telling you what it is made of, regardless of what the title says.
Three Tests After It Arrives — and What Each Actually Proves
The burn test. Reliable. Pull a single thread from an inside seam allowance. Hold it in tweezers over a sink and touch a flame to it. Silk is protein: it smells like burnt hair, it stops burning when you remove the flame, and it leaves a brittle black ash that crushes to powder. Polyester is plastic: it smells chemical or sweet, it shrinks away from the flame, and it leaves a hard bead you cannot crush. This is the only test that gives a real answer.
The ring test. Unreliable, despite what you have read. The claim is that real silk pulls through a ring and synthetics do not. In practice a thin polyester charmeuse slides through just as easily, and a heavy 22-momme silk may not go through at all. It measures thinness, not fibre.
The hand-warmth test. Suggestive, not proof. Silk takes on your body heat quickly and holds it; polyester tends to stay cool at first and then feel clammy because it does not move moisture. Useful as a first impression when two garments are side by side. Not something to buy on alone.
One more that costs nothing: crush a corner in your fist for ten seconds and let go. Silk holds a soft wrinkle that relaxes out within a minute or two. Polyester springs back with almost no crease at all — perfect recovery is a synthetic behaviour, not a luxury one.
We Label Our Satin as Satin
The reason we can be blunt about this is that we sell both, and we do not blur the line. Our Nightcap Set page says it plainly: nothing here is silk — it is the satin that behaves like it. A cool-touch knit, seven colours, priced accordingly. The Room Service Set is a satin robe, slip and thong for the same reason: it is a good satin set, sold as one.
Our Night Shift Silk Pillowcase goes further and states the construction on both sides — nineteen-momme mulberry silk on one face, polyester on the other, envelope closure, 48 × 74 cm. That is a normal way to make a pillowcase, and the only dishonest version of it is the one that does not tell you.
On the silk side we publish the numbers other brands leave off. The Plain English Silk Slip is sixteen-momme mulberry silk, graded 6A, with a 0.3 cm rolled hem. The Backhanded Silk Slip lists its weave density: twelve stitches to three centimetres. The Curtain Call Silk Slip runs fifteen stitches to three centimetres, and that tighter weave is precisely why it falls the way it does. You will not find that number on many product pages. It is the number that separates two garments with identical momme.
The Price Sanity Check
Silk is an agricultural product with a floor price. A full-length nineteen-momme set uses several square metres of it. When the total comes to the price of a takeaway dinner, the arithmetic has already answered your question — no test required. This is not a moral failing on the seller's part if the listing says satin. It becomes one when the listing says silk.
FAQ
How can you tell real silk from fake silk?
Burn a single thread from an inside seam. Real silk smells of burnt hair, self-extinguishes when the flame is removed, and leaves brittle ash that crushes to powder. Polyester smells chemical, shrinks from the flame, and leaves a hard bead. Before buying, check whether the listing publishes a momme weight and fibre grade.
Does satin mean silk?
No. Satin is a weave structure, not a fibre. Satin can be woven from silk, polyester, nylon or acetate, and most satin sold today is polyester. A listing that says only "satin" has told you how the fabric is constructed, not what it is made of.
Is the ring test a reliable way to check silk?
No. It measures how thin and slippery a fabric is, not what it is made of. Thin polyester charmeuse pulls through a ring easily, and heavy 22-momme silk may not pass through at all. Use the burn test if you want an actual answer.
What momme should real silk sleepwear be?
Sixteen momme is a genuine light slip weight and nineteen momme is where silk stops floating and starts falling. Below about twelve momme, a garment is thin enough that longevity becomes a real question. Any brand selling silk knows its momme, so treat a missing number as information.
Can real silk be machine washed?
Cool water on a delicate cycle in a mesh bag is workable, but a care label reading "machine wash warm, tumble dry" on a garment sold as silk is a contradiction — heat and alkali degrade silk protein. Read the care label as a fibre clue, not just an instruction.
Once you know it is real, see what momme actually measures and how silk and satin differ in wear, or browse the silk collection.
