How a Persian rug is made

Start with the back. Turn an old rug over and you see what the front conceals: a grid of tiny knots, each tied by hand. A pile carpet, farsh in Persian (from an Arabic root meaning ‘to spread’), is built on a loom from three elements. The warp is the set of parallel threads stretched lengthways, which become the fringe at either end. The weft is passed across them, over and under, after each row of knots to lock the row in place. The pile is everything else: short lengths of yarn tied around the warps and cut, so that the surface becomes a dense field of upright ends.

There are two principal knots. The symmetrical knot wraps around two neighbouring warps, with both ends rising between them. The asymmetrical knot wraps fully around one warp and only passes under its neighbour, so that one end comes up free; it can open to the left or to the right. The trade calls the asymmetrical knot ‘Persian’ or ‘Senneh’ and the symmetrical one ‘Turkish’ or ‘Ghiordes’, but the labels are geography at its most misleading. Both knots are tied across Iran, and the rugs of Senneh itself, today’s Sanandaj in Kurdistan, are usually tied with the symmetrical knot.

Knot density, counted per square inch or per square decimetre, is the figure collectors quote. It sets the limit of a design: a few dozen knots to the square inch will carry a bold hooked medallion, while a curling vine with tendrils needs hundreds. It is not a measure of worth. A coarse village rug with good wool and honest colour can outlive a fine one woven to hit a number.

Reading the back

Count the knots along an inch of warp and an inch of weft and you have the density. Notice whether the warps lie level or on two levels, one pushed behind the other, which tightens the weave and stiffens the handle. Look for the jufti knot (jufti means ‘paired’), tied over four warps instead of two; it halves the labour and thins the pile. Then look at the ends and the side cords, the selvedges. They are where an old rug first wears, and where a careless repair shows itself.