How to Spot Fake Silk: A Buyer's Guide

"Silk" is not a protected term in most markets, which means a garment can be labelled or marketed as silk-adjacent — "silky," "silk-feel," "satin" — without containing any actual silk fibre. Telling real mulberry silk from a polyester or viscose substitute isn't guesswork. There are specific, testable differences between a natural protein fibre and a synthetic one.

Why This Matters Beyond Feel

Real silk and synthetic imitations behave differently in ways that affect how a garment performs over years of use, not just how it feels on day one. Genuine mulberry silk regulates temperature, resists static, and biodegrades at the end of its life. Polyester satin traps heat, builds static charge, and persists in landfill for decades. If you're paying a silk price, it's worth confirming you're getting silk.

The Label Isn't Enough

Fabric composition labels are a legal requirement in most countries, so checking the label is the first step — but it isn't the last. Some sellers use "silk" loosely in marketing copy while the label discloses 100% polyester in smaller print. Always check the composition line specifically, not the product name or description.

What to Look For on a Label

A genuine silk garment will state "100% Mulberry Silk" or "100% Silk." Blended fabrics will list percentages (for example, 70% silk, 30% viscose). Anything labelled "satin" without a fibre content stated is very likely synthetic, since satin is a weave structure, not a fibre — it can be woven from silk, polyester, or nylon.

Physical Tests You Can Do at Home

If you already own the garment or can examine it in person, a few simple checks are reliable indicators.

The Friction Test

Rub two layers of the fabric together briskly. Real silk produces a distinctive, almost squeaky friction sound known in the textile trade as "scroop." Polyester and viscose satin tend to glide silently against each other with no sound at all.

The Burn Test

This test is destructive, so only use it on a loose thread or swatch, never a finished garment you intend to keep. Real silk, being a protein fibre, burns slowly, curls away from the flame, self-extinguishes, and smells like burning hair — because it's chemically similar to hair and wool. It leaves a brittle, dark, easily crushed ash. Synthetic fabrics like polyester melt rather than burn, often continue burning or dripping after the flame is removed, smell like burning plastic, and leave a hard bead of melted residue.

The Water Test

Real silk absorbs moisture readily, since it's a natural protein fibre with strong water affinity. A drop of water on real silk will typically be absorbed within a few seconds. On polyester, which is hydrophobic, a water droplet tends to bead and sit on the surface rather than soaking in.

The Ring Test

A well-known but less reliable test: pulling a length of real silk through a ring. Fine silk can pass through smoothly due to its low friction and lightweight structure, though this test is more useful for very sheer silks and less conclusive on heavier weights like 19 momme crepe satin.

Visual and Tactile Clues

Sheen

Real mulberry silk has a soft, slightly muted sheen that shifts subtly depending on the angle of light, because of the triangular prism-like structure of the silk fibre. Synthetic satin tends to have a flatter, more uniform, glassier shine that doesn't shift much with viewing angle.

Weight and Drape

Silk has a natural weight and fluid drape without feeling stiff or plasticky. Polyester satin often feels lighter and can have a slightly stiff or "crunchy" hand-feel, especially in cheaper weaves.

Temperature on Skin

Place the fabric against your skin. Real silk feels cool initially and warms gradually to match body temperature, an effect of its natural temperature-regulating properties. Synthetic fabric tends to feel closer to room temperature immediately and doesn't shift much.

Price as a Signal, Not a Guarantee

Genuine mulberry silk sleepwear has a production cost floor due to the labour-intensive nature of silk farming and weaving. A silk slip priced dramatically below market rate for 19 momme mulberry silk is worth scrutinising closely — but note that a high price alone doesn't guarantee genuine silk either, so pair price with the checks above rather than relying on it in isolation.

The Takeaway

Confirming real silk comes down to checking the composition label, then verifying with sensory tests: sound, smell, water absorption, sheen, and drape. None of these tests require special equipment, just a few minutes of attention before or after you buy.

Shop & moon's silk slips, made from 100% Vietnamese mulberry silk in a 19 momme crepe satin weave.

Written by Riccy.P, Founder & moon