No matter what the material used in the pile of Persian and Oriental rugs, the fibers are either natural or synthetic. Natural fibers are made either by insects, plants, or animals. Those produced by insects or animals are referred to as “protein fibers”, and those made by plants are known as “vegetable fibers”. Vegetable and protein fibers are both highly absorbent and will have extended drying times when washed. This is considered as a major disadvantage, because it can lead to progress of mildew, mold, shrinkage, or even dry rot in these fibers. Synthetic fibers, on the other hand, are man-made fibers that come from chemical resources. Such fibers are continuous threads that come in long lengths and so they do not have to be spun out into yarn. Synthetic fibers are manufactured using minerals and plant materials; for example acrylic, nylon and polyester come from oil and coal while viscose comes from pine trees or petrochemicals.
Wool is not only the first, but also considered to be the best of all material for production of rugs. For a detailed discussion about wool, please read our article: “Wool – The Natural Fiber”.
Silk comes from the cocoon of the silk worm. In other words, silk in continuous lengths from 300 to 1500 yards, is spun by the silk worms to produce their cocoons. The fact that silk requires a great deal of handling and processing makes it one of the most expensive fibers. China is the leading silk producer and exporter of the world. Other major silk producing countries include Japan, Italy, and India. Being naturally non flammable and very strong, silk rugs are very durable. Silk is sometimes used as the foundation of rugs, sometimes as the pile, and sometimes as both. Since it is thinner than wool or cotton threads, a rug woven on a silk foundation can have a very high number of knots per square inch (KPSI). A pure silk rug would definitely need to be washed by a competent professional.
Cotton is a natural fiber that is harvested from the cotton plant. After harvesting, cotton should be combed to remove the seeds. A cotton gin quickly separates the seeds from the fiber and combs them for spinning. As one of the most used fibers in existence today, the major use for cotton is for yarns in woven rugs, usually as the foundation. Cotton is resistant to alkaline solutions and becomes stronger when it is wet. While a single cotton fiber is not terribly solid, when multiple curling fibers are twisted together, they form a very strong and smooth thread. The greatest drawback to cotton is the fact that it is the most absorbent fiber there is, requiring extensive drying times after a wash. Also, it can easily get damaged by acids, soils quickly, stains easily, and is subject to mildew, shrinkage, and dry rot.
These are fibers from some plant or plant-based materials. They belong to one of the categories of “natural” or “manufactured”. Natural cellulose fibers are often identified as being from a part of the original plant because they are only processed as much as needed to clean the fibers for use. For instance, cotton fibers look a lot like the soft fluffy cotton balls that they come from. All “natural” fibers go through a process where they are separated from the parts of the plant that are not used for the end product, usually through harvesting, or separating from chaff. “Manufactured” cellulose fibers come from plants that are processed into a wood and then forced out in the same ways that synthetic fibers like polyester or nylon are made. Rayon (or viscose) is one of the most common “manufactured” cellulose fibers, and it can be made from wood pulp. Rayon is used for area rugs because of its silky appearance. Rather than making up the pile of a rug, these fibers are often used as backing materials of tufted as well as woven rugs.
Jute is produced by the jute plant which grows in South America, India, and Pakistan. The longer coarse fibers are obtained from the stalk of the jute plant which is located between the outer bark and within the inner pulp. Jute is normally used as weft yarns in woven
rugs and, just like cellulose fibers, as a backing material in the construction of tufted carpets. Jute is an inexpensive material that also serves other uses than just carpets. Jute has its own disadvantages, like all other fibers. It gets weak as it becomes wet and is also subject to mildew, dry rot, and shrinkage. Although jute is among the cheapest of natural fibers available, the thread created from jute is very strong. Jute also has exceptional insulating properties, low thermal conductivity, and antistatic characteristics. However, synthetic materials are replacing jute in many applications, because they are still less costly to create and more efficient to use. This is partly due to the fact that jute has a tendency to become brittle and to yellow in sunlight.