Wool Rugs

Almost every hand-knotted rug ever made has a wool pile, and the reason is mechanical rather than sentimental. Wool is springy, greasy, and it stands back up after a foot has pressed it flat. It takes dye deep into the fibre, so a worn tip stays the colour of its root. Nothing else on this list does all three. The useful question about a wool rug is not whether it is wool, but which wool and how it was spun.

Lanolin, and what the grease is for

Raw fleece carries wool grease, which the trade calls lanolin. Scouring removes most of it before spinning, and how much is left behind is one of the real differences between one lot of yarn and another. What remains makes the fibre slightly water-repellent, so a drop of something sits on the surface for a moment before it soaks in, and it keeps the yarn supple instead of brittle. Wool with the life washed out of it feels dry in the hand and looks flat on the floor. The difference is visible before anyone explains it.

Crimp, and recovery after crushing

A wool fibre is not straight. It grows with a natural wave, and a spun yarn full of those waves behaves like a bed of small springs. Press a sofa leg into a wool pile for two years, lift it, and the compressed patch comes most of the way back. That one property is why wool became the default floor fibre everywhere sheep were kept. Silk does not do it. Bamboo silk does not do it at all, which is why a walked track across one never lifts again.

Hand-spun against machine-spun

Hand-spun yarn varies along its length: a little thicker here, a little more tightly twisted there. It therefore takes dye unevenly, and when the weaver starts a new batch the field shifts tone. The horizontal bands that result are abrash, the fingerprint of hand processing rather than a fault. Machine-spun yarn is uniform, so the colour lies flat and even across the whole field. Neither is better. One gives a surface that moves in changing light, which suits tribal weaving and the vegetable-dyed Chobi and Ziegler revivals. The other suits a formal medallion, where a band of tone across an open ground would read as a mistake.

Where the fleece came from

Highland sheep wintering at altitude grow a long fibre with more grease in it than lowland fleece, and that is the wool the north-western districts have always had to hand. It is the practical reason a Heriz or an Ardebil takes generations of use, and why an Afghan rug built on similar fleece is close to indestructible. At the other end of the same animal sits kurk, sometimes spelled kork: the fine soft wool taken from the neck and shoulder, or from a first clip. Definitions vary a little from city to city. The names that ask for it are the fine workshop ones, Nain and Isfahan above all.

The wool nobody advertises

Not all wool is shorn. Fleece taken chemically from the hide of a slaughtered animal, which the trade calls skin wool or dead wool, is short, brittle and poor at holding dye. It can be spun and woven, and in cheap production it is. The rug looks acceptable when new and goes dry and dull within a few years of being walked on. There is no label for this. It is read by hand, and by the way the colour sits on a worn tip.

What wool will not do

Wool cannot be drawn as finely as silk: the fibre is thicker, the knot larger, and the tightest curve is out of reach. That is why the finest work moves to silk, or borrows it for outlines as a wool and silk rug does. Wool also sheds for its first months, felts if it is soaked and left, and fades in strong sun, more slowly than silk but it fades. Against that, it is the only pile here that can go in a hall, under a dining table and in a room with a dog, which is why a Bijar outlives the house it was bought for. If a room wants nothing underfoot at all, the answer is a flat weave, not a thinner pile.