Natural Fibers

A natural fiber is one that comes from fibrous materials found in plants, animal products and sometimes even minerals (Yates et al., 34). There are two different types of natural fibers: cellulosic, or plant, fibers and protein, or animal, fibers. Cotton and linen are cellulosic fibers, while wool and silk are protein fibers. These four commonly used natural fibers have both similar and different characteristics and manufacturing processes.

Fibers have many different characteristics. One characteristic is how well the yarn or fabric accepts dye. Wool and cotton are both absorbent, which gives them great dye affinity. Cotton especially easily absorbs rich, brilliant color. Linen holds color best when treated in a dye bath but when the fabric is printed, good dye saturation is difficult to obtain because of the density of the cellulosic fibers (Yates et al., 38). Because of this, many printed linens are designed to look worn. Another characteristic is abrasion resistance. Cotton is both resistant to abrasion and sunlight, and while silk’s smooth character makes it abrasion resistant, it is sensitive to fading. In contrast to cotton and silk, linen has a low abrasion resistance making it unpopular for upholstery. Linen is also very brittle and lacks resilience, meaning it wrinkles easily. In comparison, wool is springy and naturally regains its shape. Wool does not accept wrinkles or creases created by normal use. Both cotton and silk will blend with other fibers. Silk blends best with certain synthetics like polyester and rayon, while cotton blends well with a variety of fibers making cotton very versatile.

After being harvested, fibers go through manufacturing processes that turn the fibers into yarn and then a finished fabric. The basic manufacturing processes for wool, cotton, and linen are essentially the same because all three are naturally produced in staple form. Staple fibers are produced in “cut” lengths that vary from plant to plant and animal to animal (Yates et al., 34).Therefore, in the basic manufacturing processes of natural fibers, the length of the staple typically determines the process that will be used. For example, short-staple cotton and wool fibers are carded. This manufacturing process smoothes the fibers and arranges them approximately parallel to each other before being spun into yarn (Yates et al., 37). Long-staple cotton and wool fibers can be carded or combed. Combing is a different process that arranges the fibers more strictly parallel to create a smoother, softer, stronger, more lustrous, and more even yarn (Yates et al., 37). Longer-staple wool typically after being carded, will also be combed and then spun on different equipment than the carded wool, or woolen (Yates et al., 39). This process yields worsted yarns which are smoother and have a higher sheen than woolen. Line-linen is produced from staple fibers that typically measure almost up to a yard. These very long staples are usually combed and often mercerized creating a luxurious and durable fabric or yarn. Cotton is also typically mercerized, which is a permanent chemical process where the fiber is impregnated with a caustic soda solution that increases strength, bulk, luster, and dye affinity (Yates et al., 37).

Unlike cotton, wool, and linen, silk is a naturally produced filament fiber, which is a long continuous form of fiber (Yates et al., 35). Silk is harvested from the cocoons of moths or silkworms. Wild silk comes from wild moths that typically eat oak leaves, giving the cocoon a brownish color. These cocoons are harvested after the moth has broken out which leaves a broken filament. These filaments are then treated as staple fibers and are spun into yarn called tussah (Yates et al., 44). On the other hand, cultivated silkworms are normally fed mulberry leaves which produce an almost white cocoon. This silk is harvested before the moth matures and breaks cocoon. The filaments from the unbroken cocoon are reeled as a continuous strand creating reeled silk.

Wool, silk, cotton, and linen are all natural fibers that have both similar and dissimilar characteristics, such as dye affinity or abrasion resistance. Sometimes, these fibers also share manufacturing processes, like carding or combing. While there are similarities between these four natural fibers, their differences are what make each fiber unique and desirable in their own way for a range of functions.

BIBLOOGRAPHY
Yates, Marypaul. Fabrics: A Guide For Interior Designers and Architects. New York: W. W. Norton & Company, 2002. 34-44. Print