*3.3.1 Wool fiber*

Animal hairs are obviously natural clothing material; they protect the body from wind and rain and also soften the extremes of temperature in various climates. A typical hair contains three parts the cuticular layers or epidermis, the fiber layer or cortex, and the pith or medulla. The wool is the haircut and collected from the sheep. Therefore before elaborating about the sheep wool, it is necessary to elaborate a little about the sheep. In the wool market, they are broadly classified into merino variety and crossbred variety. Sometimes only are used for comeback variety [16].

### *3.3.1.1 Specifications for wool fiber*

*Strength:* As wool is the weakest of the natural textile fibers some wool fabrics may be made more durable by the use of selected grades of recycled wool, although durability is gained at the expense of texture and resiliency, and tenacity dry 1 to 1.7 gpd and Wet 76 to 97% of dry.

*Elasticity:* One might look upon wool's elasticity as compensation for its relative weakness depending upon the quality of wool. The fiber may be stretched from 25 to 30% of its natural length before breaking. This characteristic reduces the danger of tearing under tension and contributes to free body movements to preserve this natural elasticity. Woolen garments should be hung properly after wearing and allowed to relax sufficiently to regain their shape elongation by 25 to 30%.

*Resiliency:* Because wool fiber has a high degree of resiliency, wool fabric wrinkles less than some others, wrinkles disappear when the garment of fabric is steamed. Good wool is very soft and resilient, poor wool is harsh.

*Drapability:* Wool's excellent draping quality is aided by its pliability, elasticity, and resiliency. Wool has superior drapability than many of synthetic fibers.

*Absorbency:* Primarily wool tends to be water repellent. One can notice that precipitations of water on the surface of wool fibers are freely soft off. However, once the moisture seeps through the scales of the fibers, moisture is absorbed. The fibers have a degree of capillarity that will readily absorb about 20% of its weight of moisture without feeling damp. Moisture regains 16%, moisture content 13.8%.

*Cleanliness & washability:* Dirt tends to adhere to wool fabric. Unless thoroughly cleaned, wool retains odors, consequently, wool laundering is required.

*Reaction to bleaches:* The household bleached that contain sodium hypochlorite or other chlorine compounds are harmful to wool. However, bleach-containing hydrogen peroxide or sodium perborate may be used.

*Application:* Wools resilience bulk & ease in handling makes it the most appropriate for knitting goods. Both Woolen & worsted can be used in men's and women's suiting's, overcoats, sweaters, upholstery fabrics, and blankets.

#### *3.3.2 Silk fiber*

Silk originated from the silkworm which is cultivated in a warm shiny climate and usually employs cheap labor. The silk fabrics comprise the fabrics woven with raw silk and degummed after weaving and the fabrics woven by using the degummed silk yarn. They generally are used raw silk material to make woven cloth in white color. They are dyed on fabric surface plain color or according to consumer demand printed used. There is also a method of degumming and dyeing in which the dye is put into the degumming tank and dyeing is carried out instantaneously with scouring [17, 18].

*Strength:* Silk is a natural fiber. The continuous length of the filaments in thrown yarns provides a factor of strength above what is possible with short natural fibers. The smoothness of the silk filaments yarns has the inherent strength of silk along with its fine diameter for durable fabrics. The strength of silk fabric is also affected by its construction & its finish.

Tenacity dry 2.8 to 5.2 gpd, tenacity wet 75 to 95% of dry.

*Resiliency:* Silk fabrics retain their shape and resist wrinkling rather well. This is particularly true of the fabrics made from pure silk and from wild silk.

*Absorbency:* The good absorptive property of silk also contributes to its comfort in a normal atmosphere. Silk fiber can generally absorb about 11% of its weight of moisture, but the range varies from 10% to as such as 30%.

*Cleanliness and washability:* Silk is a hygienic material because of its smooth surface does not attract dirt, when dirt does gather; it is given up readily by washing or dry cleaning. Care should be exercised in laundering silk that always use a mild soap and strong agitation in the washing machine must be avoided as silk weakens slightly when wet.

*Reaction to bleach:* Strong bleaches containing sodium hypochlorite will deteriorate silk. A mild beach of hydrogen peroxide or sodium carbonate may be used with normal caution.

*Basic Functional Application for Natural Fibers and Types DOI: http://dx.doi.org/10.5772/intechopen.102998*

*Shrinkage:* Because of the straightness of the filament, smooth-surfaced silk fabrics have only a normal shrinkage which is easily restored by ironing.

*Effect of light:* Continuous exposure to light weakens silk faster than either cotton or wool. Raw silk is more resistant to light than degummed silk and weighted silk has the least light resistance.

*Affinity for dyes:* Generally is silk very good affinity for dyes application. It readily absorbs acid and direct dyes.

*Application:* Silk is famous for its lightness, luster, and beauty. It has a wide variety of uses in apparel and upholstery fabrics in terms of satin, crepe, printed crepe, voile, chiffon, damask, muslin, velvet, brocade (**Tables 2** and **3**).

### **3.4 The basic identification of fiber**

Generally, fiber identification is of three types microscopy view, burning test, and solubility test [19–21].


#### **Table 2.**

*Natural fiber moisture regains and density specification.*


#### **Table 3.**

*Man-made fiber moisture regains and density specification.*
