Rugs can be made of almost any thread made of a type of fiber, natural or synthetic. However, the primary fibers are the natural fibers of wool as a face yarn, and cotton as the foundation fiber. The fiber’s diameter dictates how fine a yarn can be spun. Carpet yarns are rarely spun at the limit of fineness as the coarser the wool, the more durable the rug will be. New Zealand carpet wool has a fiber diameter of 33-37 microns. Middle Eastern rugs are typically made from a combination of short, fine and crimpy wool with medullated (hollow, core-like structure within the fiber) coarse fibers ranging in diameter from 40-62 microns. The fiber’s length is determined by the time taken between instances of the sheep’s shearing. Sheep are typically sheared twice a year or three times over the course of two years. The fiber’s strength is measured in relation to its length and wool is favored for its strength and resilience.
Yarn bulk is typically determined by the fiber’s crimp. Fibers can be blended to achieve the desired level of bulk in the yarn. The natural crimp in wool allows it to absorb noise; that is, the crimp traps air between the fibers. This trapped air provides insulation and increases the fiber’s durability. Wool has moderate abrasion resilience, making it ideal in high-traffic areas. One of the desirable features of wool fiber is that it can absorb up to 30% of its weight in water and still actually feel dry. Because of this feature, combined with the ability to emit heat when absorbing water vapor, wool has a natural ability to blend with the surrounding moisture conditions. In contrast, wool does not absorb oils well, so a wool carpet releases oily residues during the cleaning process.
Weathering the damaging effects of cigarette burns, fireplace embers, and other flames shows the durability of wool. Because of its high moisture and nitrogen content, wool simply chars at the surface and extinguishes itself. This leaves an ash that can typically be brushed away. While they are resilient to some damaging effects, wool fibers are sensitive to sun and UV light, which can cause photo bleaching. Certain chemicals, such as heavy alkaline cleaning solutions, can damage the fibers and cause dye loss. Mechanical action, such as aggressively rubbing a carpet, can lead to felting. Felting occurs when the fibers lock together, or mat, in an irreversible tangle. Combining mechanical action with common cleaning materials such as soaps, moisture, and lubricants accelerates the felting process, damaging the wool irrevocably. This is one of the major reasons that it is important to have your rug cleaned by an educated professional with experience in caring for these precious items, such as Heriz Fine Antique Persian Rugs.
The quality of the wool used in making carpets can be equated to the importance of the quality of wood used in making furniture. Certain qualities to consider are the wool’s resilience, luster, and absorption. The resilience of the wool affects how well it will withstand abrasion throughout its life. The luster is subtle but affects the overall look of the rug, and its absorption factor affects how well it will soak up the dye colors used. All of these factors depend completely on the quality of the wool.
Traditional carpet wool comes from mountain sheep, typically from sheep in India, China, Spain and Wales, though today, sheep in New Zealand produce wool that is best for general carpet manufacturing. Wool from merino sheep is used exclusively for textiles. One merino sheep can produce nearly 5,500 miles of wool fibers in a single year.
Mohair is a natural fiber from the Angora goat. These goats are native of Asia Minor. Smoother than wool, mohair is translucent, springy and lustrous, and is typically not used as a carpet face material in an oriental rug. It is more commonly used, when blended with wool, in making plus upholstery material.
Cashmere is a delicate, expensive natural fiber from the fine downy hair of the Kashmir goat. These goats are native to the Himalayas, India and China. Because of its cost and fineness, it is not used in rugs.
Goat Hair is typically seen in on the sides and warps of tribal and nomadic carpets due to its extremely coarse and scratchy texture.
Camel Hair is similar to cashmere. It is from the downy under-hair of the camel. When combined with other hair, it is seen as a luxury fabric and not typically used in rug production.
Silk is known for luxury. It has been used in tapestries, rugs, fine fabrics, and other accessories for over 4,000 years. In that time, sericulture, the cultivation of silkworms for silk, has remained virtually unchanged. Discovered in China in 2600 B.C., silks eventually made their way to Greece and Rome. Though China tried to protect the process of making silk from the outside world, it eventually spread to Japan and India in the 3rd and 4th century A.D., respectively. It is a well-known credit that Marco Polo, the famous Italian merchant traveler, introduced silk production to Venice. Silk has three unique properties:
Hydroscopicity is the ability to absorb water without feeling wet. Silk can hold up to 30% of its dry weight in water.
Low Specific Gravity means that silk has a low density. The molecular structure of silk looks like a long string of ladders, and in between the “rungs” is air space. This space acts as insulation and allows the silk fiber to breathe.
Strength-in-Fineness means that silk is exceptionally strong. Because of its fineness, silk can be used to weave fabrics and rugs with up to 3,000 knots per square inch! Silk is stronger than any other natural fiber with equal diameter, including nylon and steel wire. Silk does not weaken when wet, though it will show wear through abrasion. Because of this, silk is not the ideal fabric for rugs that will be used on the floor.
Cotton is a seed hair fiber from the cotton plant. Cotton is a very durable fiber, having a high tensile strength and resistance to abrasion. It also effectively absorbs dyes. Cotton resists soil, absorbs moisture and increases its strength when wet. Because of its strength and durability, cotton is a common fiber to use as the foundation for many rugs.
The fiber is most often spun into yarn or thread for its soft, breathable textile. Cotton has been used for thousands of years. The oldest fragments of cotton fabric were dated from 5000 BC in Mexico and Pakistan and some parts of India. With the technology advancement and mass production, cotton continues worldwide, and it is the most widely used in clothing today.