Materials Used in Tribal Rugs
The materials used in the construction of a pile carpet are selected by the weaver in terms of their use in the carpet. The material used for the warp (longitudinal threads), for example, is not necessarily the same material used for the weft (crosswise threads), nor for the pile (the knotted threads). Further, the colours of the warp and weft threads may be different.
a) Pile: Generally, tribal carpets have a woolen pile, but other materials such as camel hair, mohair, silk or artificial silk (rayon) are also used. A silk pile gives a carpet brilliance, but is not as long lasting as wool. Often, in the cases of imitation silk, chemical washes can damage the pile. Further, chemical washes (usually seen in Pakistani and Kashmiri carpets) can impart a lustrous sheen to the woolen pile, but significantly affects the strength of the carpet and its longevity. Older woolen carpets have a natural sheen resulting from prolonged use and a number of conventional washings.
b) Warp: The warp threads in tribal carpets are usually made of sheep wool, but cotton or goat hair is often used. Silk is often used for warps in 20th century carpets as its strength and finess enables a higher knot density in a wool pile carpet. Often, mercerized cotton is used which is passed off by unscrupulous dealers as being silk. The colour of the wool and method of twisting (hand twist or machine twist) can also help identify the origin.
c) Weft: The weft threads are more difficult to see, but can usually be seen from the back of the carpet. These can be made of wool, but cotton and a combination of cotton and synthetics are sometimes used. Warp threads with a blue colour often identify carpets made in the Meshad areas. The number of weft threads between rows of knots is often a tell-tale sign of the carpets origin.
d) How to tell the difference: Usually one can verify the material used in a thread removed from a carpet by burning the thread. Wool burns with a bright flame - leaving a residue smelling like burnt hair. Cotton (and mercerized cotton) produces a flame and a residue like burnt paper. Silk does not burn with a flame, but simply glows and reduces to an ash. Artificial silk reacts the same way but gives off an acrid smell. Synthetics (or a combination including synthetic yarn will burn with a flame and melt to a black blob.
Structure Of Tribal Carpets
The pile carpet is made of hundreds of thousands of individual loops of wool tied by hand around a pair of warp threads (Note: for the purpose of this paper, ethreadi means a number of fibres twisted into a piece of yarn). These knots are not knots as we would think of the knot used to tie our shoes, but bits of wool thread looped around two warp threads. They are locked in place by one or more weft treads which are pounded across a row of pile knots. Despite the many variations of knotting as described by dealers such as "single knot" or "double knot", there are only two kinds of knots used:
a) The Persian Knot: One end of the pile wool piece comes up between the two warp threads and the other end comes up on one side of the two warp threads. This is also called the "asymmetrical knot".
b) The Turkish Knot: Also called the "Ghiordes or symmetrical Knot". In this knot, the pile thread is looped under both warp threads and come up between the two threads. The Turkish knot viewed from the pile side will appear as a short thread across both pile threads
The tightness of the carpet is determined mostly on the tightness of the wefts. A "Single Weft" carpet means that after a row of knots is tied; the loom pedal (shed) is operated - separating alternating rows of warp threads. The weft thread is passed from one side to the other. Another row of knots is then tied and the loom shed is reversed and the weft is passed back through. This results in a single weft thread between each row of knots. In these carpets, the warp threads will be visible.
A "Double Weft" carpet means that after a row of knots is tied, the weft thread is passed through, the loom reversed, and the weft is passed back through. The wefts are then pounded down to lock the pile. On a double weft carpet, one cannot see the warp threads. In older pieces, three wefts between rows of knots was common, and in certain tribal pieces, 5 or 6 weft threads can be seen between the rows of knots.
Sometimes, in double weft carpets, the alternating wefts are often made of different thickness, with the heavy weft being drawn tight and the lighter weft inserted with less tension. This has an effect of setting alternating warps in different planes resulting in longitudinal ridges on the back of the carpet. This effect produces a carpet that feels much stronger.
Weavers in certain locales often use weft threads died a different color in the body of the carpet (e.g. light blue / pink / red/ black). This practice often helps identify the origin of the carpet regardless of the design.
Knot count is not a major factor in Tribal Carpets- either in desirability or financial value. However, if one desires to count knots, remember that each visible turn of pile yarn as seen from the back of a carpet represents half of a knot. By using thin wefts and thin pile yarn, a carpet can be made to look exceptionally fine- as in many Pakistani carpets, but the carpet suffers in substance (and value). Another common trick is to use a eJuftii knot which picks up than four warp threads for each knot. These are common in Indian carpets.
The pile yarn is fed to the weaver from a number of balls of wool of differing colors hung above his head. The design is created by knowing when to use another color for a specific knot or group of knots. A "cartoon" or drawing is often used identifying the colors to be used knot by knot and line by line. The skill of the weaver in producing symmetrical and detailed design elements is a most important factor in the carpets beauty and value.
Pile carpets are started and finished with a Kilim, or flat woven fabric (similar to your bed sheet weave). These kelims are often decorated with separate threads woven in to make a pattern, or use different coloured weft thread. The Kelim protects the pile and can add a nice decorative touch to the carpet.