A special characteristic of all Persian carpets is that they are hand-knotted. The fabric is composed of three parts: the warp, the pile, and the weft.
The warp is the combination of threads, usually of cotton, which are arranged vertically in parallel lines between the two ends of. the loom. The pile is the visible surface of the carpet; it is made up of short threads, usually of wool knotted on to the warp. The knots are placed in rows across the width of the carpet, never along the length. The weft consists of one or more threads, nearly always of cotton, woven between one row of knots and the next.
LOOMS AND TOOLS
As we have said, Oriental carpets are made entirely by hand. Apart from the great skill and patience of the craftsman, all that their manufacture requires is a loom and a few rudimentary tools.
The looms may be divided into four types: horizontal, fixed vertical, Tabriz type vertical, and vertical with roller beam. The horizontal loom, the most primitive of the four, is very similar to the looms used by nomads to make the first carpets which were intended to take the place of animals skins on the floor of their tents. Carpets, in fact, answered both the aesthetic and functional needs of these tribes better than skins.
The horizontal loom consists of just two wooden beams between which the warp threads are stretched lengthwise. During manufacture, these warp threads are held in tension between the two beams by means of two posts tied to the ends of each beam and fixed into the ground. When the tribe wished to move on, all that was needed was to remove the two posts and roll up the made-up part of the carpet and the warp threads around the two beams of the loom. The horizontal loom was used solely by nomadic tribes.
The fixed vertical loom is also known as the village loom because it is used almost exclusively in small communities. It consists of two parallel round beams held up by two vertical supports. The warp threads are stretched between the two beamd and the knotting of the carpet is always begun from the bottom. The craftsman works seated on a board hooked on to the rungs of a ladder fixed to the vertical supports of the loom. As the work proceeds, the board is raised from rung to rung so that the worker is always at the same height as the knots.
Carpets made on this type of loom are at most the same length as the loom itself, that is, no more than about nine feet. It is possible to make longer carpets by rolling the completed work around the lower beam and stretching a second set of warp threads above on the upper beam. This method, however, does not gi ve good rusults and the two parts of the carpet often do not match. One development of the fixed vertical loom is the so-called Tabriz loom invented by the craftsmen of that town, which is now very widely used, particularly in the large carpet-making centres of Iran.
In this type of loom the warp threads run from the upper beam to the lower, passing below it and going back to the upper beam. This_~orms two parallel planes of warp, one in front and one behind. The carpet made on the front warp threads is passed under the low beam and up the back of the loom; at the same time, from the back the warp threads pass around to the front of the loom. This system enables a carpet to be made twice the length of the height of the loom.
The fourth type of loom with roller beams is a further development of the vertical loom. All the warp threads needed to make the carpet are rolled on to the upper beam, and the carpet is rolled on to the lower beam as it is completed. With this type of loom it is possible to make carpets of any length.
The tools used in the making of carpets are few and simple. They are a knife, a beater, and shears. The knife is used to cut the threads of the knot. It is entirely of metal and may have a hook at the end of the blade to assist in the formation of the knot. (This type of knife is used particularly by the craftsmen of Tabriz.)
The beater consists of a series of metal blades, the points of which are splayed to form a set of teeth. It is used to tighten the threads of the weft against a line of knots. The wide-bladed flat shears are used to clip the pile ofthe carpet.
THE RAW MATERIALS
There are three materials used in the manufacture of carpets-wool, silk, and cotton.
Wool and silk are primarily used for the knots which form the pile, and are more rarely employed as warp or weft threads, for which cotton is mostly used. Chiefly sheep's wool is used, but there is also a fairly widespread use of camelhair, used for the most part in its natural colour. The employment of goat's hair is, however, much rarer.
As far as sheep's wool or possibly lamb's wool is concerned, the long-staple kinds are, of course, preferred. Wool from the shoulder and flank of the animal is best, while the poorer quality wool comes from the legs and belly. The quality varies from place to place, the wool from mountain sheep living at low temperatures being considered to be the best. Khorassan wool is also much appreciated. Wall obtained by combing the sheep's fleece in the winter and shearing it in spring is known as kurk, and is of the highest quality. Poorer quality wool is called tabechi and is obtained from the fleece of dead animals. Lime is used in this operation, the wool is stiff, dull and rough, and becomes lifeless when dyed.
Before being used, the wool must be carefully scoured in order to remove all traces of grease. The more it is washed, the purer and more vivid are the colours when it is dyed, Among the most widely used qualities of wool are those spun by the nomadic Luri and Kurd tribes and used not only for carpets emanating from
these two provinces but also for many carpets from western Persia. In some specimens with a wool pile, particularly those currently being produced at Qum and Nain, silk is also used to heighten the effect of the decoration.
Some rare carpets of a particularly sophisticated kind have a silk pile. These are usually carpets made to order. The best-known centre for this type of work is Kashan.
Cotton is used exclusively for warp and weft threads, although an exception to this must be made in reference to some Turkish specimens, in particular those from kayseri where white cotton is used in the pile for the decoration of some motifs with a similar result to that achieved with silk.
Cotton is grown and spun in most of the places where the carpets come from. In antique carpets the warp and weft threads were nearly always in wool, or in silk in the specimens where the pile was silk also. Sometimes, for decorative reasons, silver, or silver-gilt thread was also used. In present-day manufacture, with the exception of nomad carpets which are entirely of wool, the warp and weft are in cotton and the results justify its use. In fact, cotton has less tendency to give and slacken than wool, and consequently when cotton is used, one does not find the unevenness typical of all-wool carpets. Besides, as cotton is stiffer than wool, the carpet lies better on the floor.