Home Science: Class 11 (Book 1) — Chapter 5: Fabrics Around Us

• Fibres: The basic building blocks of fabrics; tiny, fine hair-like structures.
• Yarns: Continuous strands of textile fibers or filaments created by twisting, interlacing, interlooping, or knotting fibers together.
• Textiles: A general term applied to fibers, yarns, and fabrics.
• Finishing: Chemical or physical treatments applied to ready fabrics to improve appearance (cleaning, whitening, coloring), luster, texture, or serviceability.

• Spinnability: The most essential property; the ease of converting fibers into yarn, determined by length, strength, flexibility, and surface structure.
• Aesthetic & Comfort Properties: Color, luster, weight, elasticity, moisture absorption, and dye absorption.
• Utility & Maintenance Properties: Abrasion resistance, resistance to heat, chemicals, soaps, detergents, and biological organisms (moths, mildew).

Fibers obtained directly from nature (plants, animals, or minerals):

• Cellulosic Fibres:
  • Seed hair: Cotton, kapok
  • Bast fibers (from stem): Linen (flax), hemp, jute
  • Leaf fibers: Pineapple, agave (sisal)
  • Nut husk fibers: Coir (coconut)
• Protein Fibres:
  • Animal hair: Wool, specialty hair (goat, camel), fur
  • Animal secretion: Silk
• Mineral Fibre: Asbestos
• Natural Rubber

Fibers produced artificially by modifying natural materials or synthesizing chemicals. The first manufactured fiber was Rayon (commercially produced in 1895), historically called "Artificial Silk" or "Art Silk".

• Regenerated Cellulosic Fibres: Rayon (cuprammonium, viscose, high wet-modulus)
• Modified Cellulosic Fibres: Acetate (secondary acetate, triacetate)
• Protein Fibres: Azlon
• Non-cellulosic (Synthetic) Fibres: Nylon, Polyester (terelene, terrene), Acrylic (Orlon, cashmilon), modacrylic, spandex, rubber
• Mineral Fibres: Glass (fibreglass), Metallic (lurex)

1. Spinning Solution: Solid raw materials are converted into a liquid form of specific viscosity via chemical action, dissolution, or heat.
2. Extrusion: The solution is passed through a spinnerette (a small thimble-shaped nozzle with fine holes) into an atmosphere that hardens or coagulates it into fine filaments.
3. Stretching & Texturisation: Hardened filaments are collected, stretched for fineness and molecular orientation, or texturized to improve stretch and bulk.

1. Cleaning: Natural fibers are cleared of extraneous impurities (seeds, leaves, twigs, suint) and converted into laps (rolled sheets of loose fibers).
2. Making into a Sliver: Laps are unrolled and subjected to carding (disentangling and straightening fibers) and combing (removing short fibers and fine impurities for high-quality fabrics). The fibers are then drawn through a funnel to form a sliver (a loose rope-like mass of fibers, 2-4 cm in diameter).
3. Attenuating, Drawing Out, and Twisting: Multiple slivers are combined for uniformity and drawn out. The sliver is processed in a roving machine where its diameter is reduced to $\frac{1}{4}$ to $\frac{1}{8}$ of its original size, and a slight twist is added.
4. Spinning: The strand is stretched to its final fineness, given the desired twist, and wound onto cones.

• Yarn Number: An indicator of the fineness of the yarn based on the relationship between weight and length. A higher yarn number indicates a finer thread.
• Yarn Twist: The twist added to hold fibers together, measured in t.p.i. (twists per inch). Loose twists yield softer, more lustrous yarns; tight twists yield strong, ridged yarns (e.g., denim).
• Yarn vs. Thread: Yarn is the primary material used to manufacture fabrics, whereas thread is a finished product used to stitch or join fabric pieces together.

• Felts and Non-wovens (Bonded Fibre Fabrics): Formed by laying fibers in a web or mat and bonding them together using heat, moisture, adhesion, or pressure.

• Weaving: The oldest fabric construction method. It involves interlacing two sets of yarns at right angles on a machine called a loom.
  • Warp: Yarns fitted lengthwise on the loom; runs parallel to the selvedge (the self-finished bound edge of the fabric).
  • Weft (Filling): Yarns interlaced widthwise across the warp.
  • Weaving variations include using attachments like dobby or jacquard for complex figurative designs, or adding extra yarns to create loops for pile fabrics (uncut in towels, cut in velvet and corduroy).
• Knitting: The construction of fabric by interlooping one or more sets of yarns.
  • Weft Knitting: Loops are formed across the width of the fabric; can be done by hand or machine. Highly elastic, porous, and comfortable (used for socks, t-shirts, sportswear).
  • Warp Knitting: Loops are formed along the length of the fabric; done on industrial machines to produce continuous, run-resistant fabrics.
• Braiding: Plaiting three or more yarns diagonally from a single source (used for shoelaces, ropes, and wire insulation).
• Nets: Open-mesh fabrics made by inter-knotting yarns.
• Laces: Decorative openwork fabrics made by twisting, interlooping, and knotting yarns into intricate designs.

• Change Appearance: Cleaning (scouring, bleaching), straightening, and smoothening (calendering, tentering).
• Change Texture: Starching, sizing, or special calendering.
• Change Behavior: Wash-and-wear, permanent press, water-repellent, mothproof, flame-retardant, and preshrinking (sanforisation).

• Dyeing: Applying color uniformly using chemical dyes. Can be done at the fiber stage (for heather effects), yarn stage (for checks and stripes), or fabric stage (for solid colors, batik, or tie-and-dye).
• Printing: Localized application of color in specific designs. Done using hand tools (blocks, stencils, screens) or industrial machinery (roller printing, automatic screen printing).

A natural cellulosic staple fiber obtained from the seed pod of the cotton plant. Fibers are separated from seeds via ginning and pressed into bales.

• Properties: Short length (1-5 cm); dull appearance; rough texture; heavy; highly absorbent; comfortable for summer.
• Common Fabrics: Muslin, cambric, poplin, latha (long cloth), casement, denim, sheeting.

A natural cellulosic bast fiber obtained from the stem of the flax plant. Stems are rotted in water via retting to isolate the fibers.

• Properties: Longer and finer than cotton; stronger and more lustrous; highly absorbent; difficult to dye; limited global cultivation.

A natural protein fiber obtained from sheep or specialty animals (goats, rabbits, camels). Hair is removed via shearing as a single sheet called fleece, sorted, cleaned via scouring, and cleared of vegetable matter via carbonisation.

• Properties: Length varies (4-40 cm); natural crimp (waviness) provides high elasticity and resilience; surface scales make it water-repellent externally but highly absorbent internally.

A natural protein filament fiber produced by the secretion of silkworms. Cultivated silk production is called sericulture. Wild silk (e.g., tussar) is coarser and stronger.

• Properties: Long, fine, smooth, and highly lustrous; contains natural gum; exceptionally strong with moderate elasticity.

A manufactured regenerated cellulosic fiber made by chemically treating wood pulp.

• Properties: Uniform diameter; clear and lustrous; behaves similarly to cotton but has lower wet strength and durability; silk-like appearance.

The first true synthetic fiber, synthesized entirely from chemicals.

• Properties: Smooth, shiny, uniform; exceptionally strong and abrasion-resistant; highly elastic; used in hosiery, swimwear, and carpets.

A synthetic fiber also known as Terylene or Terene.

• Properties: Uniform, rod-like, and partially transparent; extremely low moisture absorption (uncomfortable in hot, humid weather); highly wrinkle-resistant; widely blended with cotton, wool, and rayon.

A synthetic fiber commonly known as Cashmilon, designed as a wool substitute.

• Properties: Closely resembles wool; cheaper than natural wool; high elongation and good elastic recovery; lightweight.

Highly elastic, rubber-like synthetic fibers such as spandex or Lycra. Typically blended in small percentages with other fibers to add stretch.