Wool being the commonly used material for carpets goes through several processes to get the desired yarn. Silk is used primarily for accent because it is not as strong and is more expensive. Cotton is sometimes used in the foundation, but is not seen in the pile. The combination of these materials makes for an extremely strong carpet. First, the wool is carefully sorted and cleaned shedding unwanted particles like dust and grease. After which it is washed thoroughly and dried under the sun. The wool is then spun by hand which is a time-consuming task but essential to get the perfect quality yarn. Besides, there are modern methods of feeding the wool into a machine or say spinning wheel that separates the wool and pulls it into different strands. This way the wool is spun into yarn. The yarn spinning process is repeated until the yarn becomes twisted and strong enough. Some prefer washing the yarn again in clean water to remove all remnants of dust and waste. The thickness of the yarn depends on the quality of the carpet.
This process is important because when unprocessed materials come, those are dirty, contains dust and grease. So in the washing process, these are removed. Yarns are simply washed by detergent and it is then sun-dried for two or three days.
Wool. The best and most widely used rug making material. It is soft, durable and easy to work. However, the quality varies considerably and not all wool is suitable for rug making. Good carpet wool needs to combine softness with strength and springiness, otherwise the rug wears out quickly and fails to return to its original shape if creased or depressed. Only certain types of wool possess the qualities required; the best comes from lambs between 8 and 14 months old, particularly those from the colder high land regions.
Cotton. Normally only used for foundations. The main exception of this rule is Kayseria, in Anotolia (Turkey), which produces rugs with mercerized cotton piles normally marketed as “Art” (Artificial) Silk. Cotton is grown in most rug making countries in the East, particularly in India and Persia, and is consequently in plentiful supply. As a foundation material it has numerous advantages : it is strong, does not lose its shape and can be spun into strands sufficiently thin to allow fine weaving. It is, however, susceptible to mildew.
Silk Produced by the larva of a species of moth (bombix mori) commonly called the silkworm. It is native to China and has been cultivated successfully in a number of countries, including Iran, Turkey, India, and the former Soviet Union. The finest silk for rug making traditionally comes from China and an area around the Caspian Sea. This latter region produces a type referred to as Rasht Silk, which is generally regarded as the best in the world.
Silk is used either on its own or in combination with wool by a number of individual weaving groups in all the major rug making countries, with the exception of Pakistan, where very few silk or part silk rugs are produced. Silk has a number of limitations. It is reasonably hard wearing but it lacks the springiness and suppleness of wool; consequently, silk rugs tend to retain any creases or scuffing in the pile, and far greater care is needed to protect them from damage. It is also extremely expensive, and only the most profligate would consider using a pure silk rug as a functional floor covering. However, its physical beauty is unsurpassed and silk rugs are normally used as decorative, rather than functional examples of textiles art, either as wall hangings, or floor coverings in rooms that rarely see practical use. Silk is also used as a foundation material; it is extremely strong, keep its shape, and can be spun into very fine strands, but because its cost it is only used when exceptionally fine knotting is required.