GCSE DT: Core Content (1): Fibres & Textiles

Textile

All flexible fabrics created from fibres

Fibres

Thread-like elements that can be formed into yarns and fabrics by weaving, knitting or felting

Fabric

a length of flexible material constructed from fibres

Staple

length of a fibre

Examples of natural fibres from plant sources

Cotton, flax, hemp, sisal, jute, coconut

Examples of natural fibres from animal sources

Silk, wool, mohair

Wool properties

- From animal's fleece, made of protein molecules

- Produces a short fibre with a crimp or kink which, with the scales on the fibre, traps air, creating warmth

- May be soft or coarse, depending on sheep breed

Wool uses

Coats, jumpers, suits, blankets, carpets, upholstery

Wool advantages

Warm, absorbent, breathable, durable, repels rain, hangs well, creases drop out

Wool disadvantages

Dries slowly, susceptible to moth attack, can feel itchy, washes poorly, can shrink, heavy when wet

Cotton properties

- 'Bolls', the fruit cotton plant's fruit, are machine-harvested

- Saw teeth remove waste from the seed pod and the resulting fibre is called lint

- Cellulose makes the fibre strong, durable and absorbent

- Twenty to 30 layers of cellulose are coiled in natural springs

- As the cotton fibres dry they form interlocking flat, twisted, ribbon-like shapes, ideal for spinning

Cotton uses

- Towels, denim, socks, underwear, T-shirts, bedding

- Shorter fibres make bandages and insulation

Cotton advantages

Cool, absorbent, soft, resists abrasion, withstands frequent washing at high temperature, good drape, durable, does not stain easily, static and cling resistant, available various weights, can be ironed at high temperatures, good colour retention

Cotton disadvantages

Creases easily, burns, shrinks, dries slowly

Synthetic fibres examples

Polyester, Acrylic, polyamide (nylon), elastane (Lycra), Kevlar

How artificial fibres are usually made

Coal, petroleum products

Polyester properties

Simple chemical molecules (monomers) are joined to form polymers by polymerisation

The polymer chains are spun into a yarn

Polyester uses

Raincoats, fleece jackets, children's nightwear, medical textiles, working clothes

Polyester advantages

Strong when wet or dry, dries quickly, resistant to abrasion, soft, hangs well, durable, crease and stain resistant, easy care, can be recycled, resists bacteria

Polyester disadvantages

Damaged by acids, low warmth, poor absorbency, does not breathe, not environmentally friendly

Acrylic properties

Formed by polymerisation of at least 85% acrylonitrile or vinyl cyanide

The double bond between the first two carbon atoms is broken and the molecules join in a chain

Acrylic uses

Imitation wool knitwear, upholstery fabrics, sportswear, fleece jackets, blankets

Acrylic advantages

Warm, dries quickly, good drape durable, crease resistant, easy care

Acrylic disadvantages

Poor absorbency, feels stiff, can irritate skin

How woven textiles are usually made

Weaving turns yarns into a fabric on a loom, which has an arrangement of warp (vertical) threads held under tension. The edges were the weft (horizontal) threads loop back form a non-fraying edge (selvedge)

Plain weave - calico properties

A simple cotton cloth

The warp and weft pass over and under each other, forming a criss-cross pattern that looks the same on both sides

Calico (muslin) is naturally grey

May be soft or coarse

Plain weave - calico uses

Shirts, bags, bedding, textile crafts

Plain weave - calico advantages

Strong, hardwearing, hangs well, same both sides, cheap to make, good background for printing and applied surface designs

Plain weave - calico disadvantages

Firm, varied quality

Twill weave - denim

The weft yarn goes over two or more warp threads, repeated on the row but steps over one warp thread on the next rows to make a diagonal pattern

Denim is blue in the warp and white in the weft

Twill weave - denim uses

Jeans, jackets, curtains, blankets, soft furnishings

Twill weave - denim advantages

Hardwearing, strong, hangs well, less stiff and more interesting to look at than plain weave

Twill weave - denim disadvantages

Frays, thickness makes it hard to use

How non-woven textiles are made

Fibres are layered at different angles to form a web, joined by either felting or bonding, Bonding joins the fibres with heat, solvents or adhesives, so is cheap to produce but not as strong as woven or knitted fabrics.

Felted wool fabric properties

Scaly fibres of wool hair become tangled as they are rubbed together when wet

Heat and pressure are applied to join them.

Felted wool fabric uses

Pool table surfaces, hats, bags, coats, wall hangings, slippers, appliqué quilts

Felted wool fabric advantages

Resists chemicals and fire, does not unravel or fray, can be repeatedly compressed and released without deforming, excellent sound insulator, environmentally friendly

Felted wool fabric disadvantages

Expensive, no drape, not stretchy, deforms when wet

Bonded fibres/webs properties

Does not fray

Weaker when wet

Can be produced in a range of weights

Not very strong

Bonded fibres/webs uses

Fusible interfacing, wet wipes, disposable overalls

Bonded fibres/webs advantages

Does not fray, cheap to produce, stable and so retains shape

Bonded fibres/webs disadvantages

Not very strong, does not drape, sometimes weaker when wet

How knitted textiles are made

Interlocking loops of yarn and are either warp or weft.

Warp Knitted fabric properties

Formed by vertical loops like a series of chains

Can only be produced on a machine

Warp Knitted fabric uses

Swimwear, geotextiles, lace, nets and fleece

Warp-knitted fabric advantages

Fairly stretchy, retains heat, does not unravel

Warp-knitted fabric disadvantages

Can lose shape, curls at the edges

Weft-knitted fabric properties

A single yarn creates interlocking loops across the fabric

If a loop breaks, a hole forms and ladders

Made by hand or machine

Weft-knitted fabric uses

T-shirts, jumpers, tops, socks

Weft-knitted fabric advantages

Stretchy, comfortable, fast production

Weft-knitted fabric disadvantages

Ladders easily

Elasticity

Amount of stretch

Tested by gradually increasing the force on the fibres until breaking point.

At low loads the fibres obey Hooke's law - stretch is proportional to the load and the fibres will return to their original size.

Clothes made from fibres that recover will maintain their shape and not keep creases.

Resilience

Resistance to being deformed or compressed

Fibres should spring back vigorously when pressure has been applied.

Loft (compressional resiliency) is the ability to return to original thickness after being compressed or squashed, or to resist creasing.

Durability

Ability to resist wear

Depends on the choice of fibres and fabrics, and the user's activities and size