Three quite different materials are sold under the word silk, at prices spanning two orders of magnitude. Telling them apart is the single most valuable skill in this corner of the market, and it is not difficult.
What each one actually is
| Real silk | Art silk (viscose) | Mercerised cotton | |
|---|---|---|---|
| Source | Silkworm cocoon — protein | Wood pulp — regenerated cellulose | Cotton, caustic-treated |
| Sheen | Deep, shifts with angle | Bright, flatter, uniform | Bright, slightly waxy |
| Wet strength | Reduced | Collapses | Good |
| Water marks it | No | Permanently | No |
| Durability | Poor underfoot | Very poor | Moderate |
| Cost | Very high | Low | Low–mid |
| Honest name | Silk | Viscose / rayon | Cotton |
Real silk is a protein filament from the cocoon of Bombyx mori. It takes an extraordinary knot count — the finest Persian and Chinese work is silk because no other fibre resolves that detail — and it has a directional sheen that makes the same rug read light from one end of a room and dark from the other.
Art silk is viscose, and the names are designed to suggest otherwise: artificial silk, bamboo silk, banana silk, rayon, modal, lyocell. It has genuine sheen and essentially no durability, and water alters it chemically — how to clean a viscose rug.
Mercerised cotton is ordinary cotton treated with caustic soda, which swells the fibre, straightens it and gives it lustre and better dye uptake. It looks convincingly silky, it is far tougher than viscose, and the honest label is "cotton". It is common in Turkish Kayseri production.
The four tests
1. The burn test — conclusive
One fibre, pulled from the fringe or an inconspicuous edge. This settles it, and everything below is a supporting indicator rather than proof.
- Real silk
- Smells of burnt hair. Self-extinguishes. Brittle black bead.
- Viscose
- Smells of burning paper. Burns on. Soft grey ash.
- Cotton
- Smells of burning paper. Burns fast. Fine grey ash.
- Wool
- Burnt hair, like silk. Bead crushes to powder.
- Nylon / polyester
- Melts, does not burn. Hard plastic bead.
Silk and wool both smell of burnt hair, because both are protein. Silk burns more slowly and leaves a smaller, harder bead; wool is coarser and the smell is stronger. Neither can be confused with the burning-paper smell of viscose or cotton, and that is the boundary that matters commercially.
Ask to do it. The answer is the test.
Any dealer selling a genuinely silk rug will let you burn a single fibre — it costs them nothing and it settles the question in their favour. Reluctance is itself the result. Do it over a hard surface, with one fibre, well away from the rug.
2. Rub it hard
Press your palm flat and rub briskly for several seconds.
Real silk warms noticeably. It is a poor conductor and the friction is felt immediately.
Viscose and cotton stay cool, or warm far less.
Rough, quick, and surprisingly reliable once you have felt the difference on a known silk.
3. Look at the back and count
Silk's whole commercial argument is fineness. A silk rug at a coarse knot count is a contradiction — nobody spends silk money on yarn and then weaves it loosely.
Turn the rug over. Genuine silk pile is usually 200 KPSI and often far higher; the fine Persian and Chinese work runs past 500. A rug with a silky sheen and 60 knots per square inch is not silk — see the anatomy of a rug and hand-knotted rug quality.
4. Check the fringe
On a hand-knotted rug the fringe is the warp continuing out of the foundation, so on a genuinely silk rug the fringe is usually silk too.
A cotton fringe on a rug sold as all-silk means either a silk pile on a cotton foundation — common, legitimate, and it should be priced and described that way — or a substitution somewhere. Ask which, and get the answer written down.
What to pay for what
Real silk commands a very large premium and mostly is not a floor covering. It has almost no abrasion resistance, less when wet, and it flattens permanently underfoot. It belongs on a wall, in a low-traffic room, or in a collection — silk rugs.
Mercerised cotton is a reasonable, durable product at a cotton price. Described as cotton it is honest; described as silk it is not, and the price gap is enormous.
Art silk is worth buying only knowingly and cheaply, and knowing it will mark.
Where the deception concentrates
Not usually outright lying. Usually omission and regional shorthand — a name that means silk in the trade, a description of sheen and knot count with the fibre left unstated, a certificate written by the seller.
Two habits cover it:
Ask for the fibre plainly, for pile and foundation separately, and get both on the invoice. That converts a verbal claim into recourse.
Do the burn test on anything expensive.
The wider inspection sequence is in the rug buying guide, the claims worth recognising early are in antique rug red flags, and the independent-verification route is rug authentication.
Common questions
How can you tell if a rug is real silk?
The burn test is conclusive and needs one fibre from the fringe or an edge. Real silk is protein: it smells of burnt hair, self-extinguishes, and leaves a brittle black bead that crushes to powder. Viscose is cellulose — it smells of burning paper and leaves soft grey ash. Any seller of a genuinely silk rug will permit this test.
What is mercerised cotton sold as?
Usually "silk" outright, or under regional names implying it. Mercerisation treats cotton with caustic soda to give it lustre and dye affinity, and the result looks convincingly silky. It is far more durable than viscose and far cheaper than silk, and the honest description is simply cotton.
Is art silk worth buying?
Only knowingly and cheaply. Art silk is viscose — regenerated wood pulp — and clean water marks it permanently. It has a real sheen and no durability, and the problem is not the material so much as that it is routinely sold at prices that imply something else.