(Posted on 16/05/17)
Most Persian rugs are pile-woven, the knots tied by hand to the warp strings. Two factors are important when discussing knots – knot density and knot type.
Knot Density: Knot density refers to, and is measured by, the number of knots per square inch (KPSI). This is done by counting the number of knots in an inch down the warp and across the weft and multiplying these figures together. Knot density could be a factor in the value of a rug, but this is not always true. In nomadic and some village items, knot density is usually not a factor. It is not a factor for collectors of these rugs either because nomadic and village rugs are judged by different standards than workshop rugs. Nomads and village groups do not have the same sophisticated tools as other city weaving groups. Their items are valued by the fact that their designs are created from memory, their dyes and materials are provided from the nature around them, and most importantly the weavers’ way of life is expressed in them. These rugs generally have a knot density of between 25 to 100 knots per square inch. Rugs with higher knot density take a longer time to make, and since nomads migrate as the seasons change, if their rugs are not finished in time for the migration, they will have to carry the looms with them. Therefore, their rugs tend to have a lower knot density than workshop rugs. The value of these rugs lies in their heritage and simplicity. They have artistic value. However in many city and workshop rugs, knot density is vitally important to determining the price of a rug. Similar to television resolutions the more knots (or pixels) per square inch the sharper the design (or picture). A skilful weaver is able to tie a knot in about ten seconds, meaning 6 knots per minute or 360 knots per hour. That means it would take a weaver around 6,480 hours to weave a 9×12-foot rug with a density of 150 knots per square inch. Divide this number by 8 (an 8-hour working day) and it would take one weaver 810 days (approximately two and a half years!) to weave such a rug. A rug as large as a 9×12 is usually woven by two or three weavers, so the above time can be reduced by half or third but the labor costs increase. This is one reason why most Persian rugs are to be considered prestigious items.
Knot type: The different types or styles of knots have been culturally developed by the different groups and tribes of people as time progressed.
The Asymmetrical (Persian or Senneh) Knot.
The asymmetrical knot is used in Iran and nearby countries such as India, Turkey, Egypt and China. To form this knot, yarn is wrapped around one warp strand and then passed under the neighboring warp strand and brought back to the surface. With this type of knot a finer weave can be created.
The Symmetrical (Turkish or Ghiorde) Knot.
The symmetrical knot is used in Turkey, the Caucasus and northern Iran. It is also used in some European rugs. To form this knot, yarn is passed over two neighboring warp strands. Each end of the yarn is then wrapped behind one warp and brought back to the surface in the middle of the two warps.
The Jufti Knot.
The Jufti knot can be seen in the rugs of the Khorasan, Iran. This knot can be either symmetrical or asymmetrical and is usually tied over four warps making the weaving process faster.