Silk Rug Guide: How to Tell Real Silk from Art Silk
A silk rug has a pile of filament reeled from silkworm cocoons — a protein fiber, not a plant one. Cocoon silk warms under a rubbed palm, chars and smells of burnt hair in a flame, and shifts color as you cross the room. Mercerized cotton and bamboo viscose sold as silk do none of these.
Silk is the corner of the rug market where the label and the material part company most often. English even has a name for the substitute: art silk, short for artificial silk, and the material behind that name is usually mercerized cotton or bamboo viscose. Neither fiber is bad. The deception is a cellulose rug sold under a protein fiber's name at a protein fiber's price. What follows is how to settle the question with a rug in front of you, and what the answer "yes, it is silk" still leaves open.
What silk is, and why it can be knotted so fine
Silk is a protein filament that a silkworm extrudes as a liquid and that hardens on contact with air.
The body of the filament is a protein called fibroin, closely related to the keratin in wool; the gum that holds two filaments together in the cocoon is sericin, and it is boiled off before the yarn is dyed. One farmed cocoon yields several hundred meters of unbroken filament, and up to about a thousand in the best mulberry grades.
That continuity is the whole difference. Cotton and wool are short fibers spun into a thread, so their strength depends on twist and their surface is a field of fiber ends. Silk yarn is a long filament wound rather than spun, which makes it far finer at the same strength and gives it a smooth, unbroken surface. Fineness is what allows the knot counts that silk rugs reach, and smoothness is why a silk field reads pale from one end of the room and several shades deeper from the other.
Touch and temperature: the first two tests
Both are free, neither damages anything, and together they settle most cases before you get anywhere near a match.
- First touch. Lay a flat hand on the pile without moving it. Silk feels cool for a moment and then warms quickly against the skin, because a protein fiber conducts heat away and then reaches your temperature. Viscose and mercerized cotton feel cool and stay cool. The pile also feels soft but firm — silk has spring in it, where viscose feels slack.
- The rub. Press an open palm down and rub it hard back and forth across the pile for three or four seconds, then rest the hand still on the spot. Silk generates noticeable warmth under friction and holds it. Cellulose fibers do not warm in the same way. This is the oldest test in the trade and it remains the most useful one you can run without permission.
Two supporting observations are worth making while your hand is on the rug. Silk lies in one direction, so walking to the opposite end and looking back should change the value of the field markedly; a shine that looks identical from both ends is a warning. And a viscose pile crushes where it is pressed and keeps a bright, flattened mark, while a silk pile lifts most of the way back within a day.
The fringe is the warp, not the pile
The fringe is the ends of the warp threads that the rug was knotted onto, which means it tells you what the foundation is made of and nothing at all about the surface you are buying.
This is the single most common misreading in the market, and it cuts both ways. A silk pile knotted on a cotton warp — an ordinary, honest and durable construction — has a cotton fringe. Burn a filament of it and you get the paper smell and the gray ash of cellulose, on a rug whose pile is genuinely silk. In the other direction, a workshop can knot a viscose pile onto a silk warp so that the fringe passes a test the rug would fail.
So read the fringe as information about the structure. A silk warp is fine, slightly translucent and surprisingly strong for its diameter; a cotton warp is matte, thicker and chalkier. Where the whole rug is silk, warp and pile together, it belongs to the narrower category shown in pure silk rugs. Then check one more thing at the same end: on a handmade rug the fringe is a continuation of the warp and cannot be pulled away, while on a machine-made rug it is a separate band sewn or glued on.
The burn test, and what each fiber does
Burning is the only field test that is close to conclusive, and it must be done on a single filament, with the owner's permission, over something that will not catch.
Take one strand — from a tuft the rug has already shed, from the back where a knot end protrudes, or, understanding the caveat above, from the fringe. Hold a flame to it for a second, then take the flame away and watch what happens next. Smell the smoke, and crush the residue between finger and thumb.
| Fiber | In the hand | In the flame | Smell | Residue |
|---|---|---|---|---|
| Silk (cocoon filament) | Cool at first, warms under a rubbed palm; springy | Chars and curls, does not flare; stops burning when the flame is withdrawn | Burning hair or feathers | Brittle black bead that crushes to powder |
| Wool | Warm, dry, elastic | Same as silk: chars, self-extinguishes | Burning hair, heavier and more acrid | Crushable black ash |
| Mercerized cotton (art silk) | Cool, stays cool, slightly stiff | Burns fast with a yellow flame and keeps burning; may glow at the tip afterward | Burning paper | Soft light-gray ash |
| Viscose, bamboo, modal | Cool, slack, very soft | Burns faster still, keeps burning | Burning paper, slightly chemical | Soft gray ash, very little of it |
| Polyester or nylon | Cool, slick, plasticky | Shrinks away from the flame, then melts and drips | Sweet or acrid chemical smell | Hard shiny bead that will not crush |
The two families to separate are protein and cellulose, and the smell does most of the work: hair means silk or wool, paper means cotton, viscose, bamboo or modal. A hard bead means the fiber was never natural at all. Bamboo and modal are both regenerated cellulose and behave as viscose does, which is why they cannot be told apart by burning; see bamboo rugs and viscose rugs, which are sold under their own names.
The price signal, and the grades inside "real silk"
Price is a test, and a cheap rug labeled pure silk is answering the question for you.
A silk rug is expensive for two independent reasons that multiply together: the fiber is reeled by hand from cocoons, and the fineness of that fiber invites knot counts that wool never reaches, so the same square meter takes many times longer to weave. A rug offered as pure silk at anywhere near the price of a machine-made rug of the same size is not pure silk, and no explanation makes that arithmetic work.
Establishing that a rug is silk is not the end of the question, because "silk" covers a ladder of grades that differ in price by a wide margin.
- Mulberry silk — reeled from the cocoon of the farmed Bombyx mori moth, fed on mulberry leaf. One continuous filament of up to about a thousand meters, white, fine and even. This is the grade behind the Hereke tradition and behind Bursa-reeled Turkish silk.
- Tussah, or wild silk — reeled from the cocoons of wild Antheraea moths. Filaments of roughly three to four hundred meters, naturally gold-beige, thicker, more matte, harder to degum, and notably hard-wearing.
- Spun silk — made from broken and pierced cocoons, whose short fibers are carded and spun like wool. Genuinely silk, less lustrous, and much of what is woven into coarser silk rugs.
- Sari silk — old silk saris unpicked, sorted by color and respun. Recycled real silk, many-toned and textured, used in modern design rugs.
This ladder is why two rugs, both honestly labeled pure silk, can be priced a long way apart. The useful question does not end at "is it silk"; it continues with "which silk, and where was it reeled". The Turkish answer to that has for nearly two centuries been Hereke — the imperial workshop founded in 1843 on the Marmara coast, weaving mulberry filament with the symmetrical Gördes knot. Its story is set out in what a Hereke rug is, and the same designs were rewoven for a wider market in Kayseri, in silk and in mercerized cotton alike.
Where the tests still fool people
Four situations account for most wrong calls, and all four are avoidable once you know them.
- Fine knotting read as proof of silk. It is not. Density measures the drawing a rug can carry. Fine wool rugs exist, and so do coarse rugs in one hundred percent silk — village and tribal pieces woven from spun silk waste are knotted no finer than wool.
- A silk-and-wool rug judged by the wrong spot. Many rugs use silk only in chosen motifs, on a wool ground. Test the shining parts and the matte parts separately, and expect different answers.
- A shine that is only finishing. Wool can be chemically washed to raise luster, and a viscose pile can be sheared and pressed to look like silk in a photograph. Neither survives the rub test.
- A signature. A woven cartouche or a workshop name proves that someone wove a cartouche. It is worth something alongside the physical tests and nothing instead of them.
Living with the result is a separate matter from buying it. A silk pile is thin, crushes under a heavy leg and marks when wet, so it belongs in a study, a bedroom, a formal sitting room or on a wall rather than in a corridor. Vacuum with the beater bar off and along the pile, blot rather than rub, and send it only to a washer who handles silk specifically. The full range is in silk rugs.
Frequently asked questions
How do you tell a real silk rug from an artificial silk one?
Rub an open palm hard across the pile for a few seconds. Cocoon silk warms noticeably under the hand; mercerized cotton and viscose stay cool. To confirm, burn one loose filament: silk chars into a brittle black bead, smells of burning hair and stops the moment the flame is taken away.
What is art silk?
Art silk is short for artificial silk, and in the rug trade it usually means mercerized cotton — cotton treated under tension in caustic soda so the fiber swells, straightens and takes a shine. It is a legitimate material sold under its own name and a deception sold under silk's.
Does the fringe tell you whether a rug is silk?
Only about the foundation. The fringe is the warp, the threads the rug is knotted onto, so a silk pile knotted on a cotton warp has a cotton fringe and is still a silk rug. A silk fringe on a silk pile means the whole structure is silk.
What does silk do in a flame, and what does viscose do?
Silk is protein: it chars rather than flares, smells distinctly of burning hair, self-extinguishes when the flame is withdrawn, and leaves a brittle black bead that crushes to powder. Viscose, bamboo and cotton are cellulose: they burn on with a yellow flame, smell of burning paper and leave soft gray ash.
What is the difference between mulberry silk and tussah silk?
Mulberry silk is reeled from the cocoon of the farmed Bombyx mori moth as one continuous filament, and it is the finest, whitest and most even grade. Tussah is reeled from wild Antheraea cocoons: shorter in filament, naturally gold-beige, coarser and more matte, and very hard-wearing.
Can a coarsely knotted rug be pure silk?
Yes. Village and tribal rugs woven from spun silk waste rather than reeled filament are genuinely one hundred percent silk and are knotted no finer than a wool rug. Knot fineness measures the drawing a rug can carry, not the fiber it is made from.
Why is a real silk rug expensive?
Because the fiber is reeled by hand from cocoons and then knotted at densities that wool cannot reach, which multiplies weaving time. A rug offered as pure silk at a price close to a machine-made one is almost never silk, and the price itself is a usable test.