FABRIC & GARMENT FINISHING

INTRODUCTION TO FABRIC, GARMENT

FINISHING

FINISHING

Application on woven, knitted, non-woven textiles

To enhance the aesthetic function To enhance performance properties Modification of appearance, behavior or

appearance & behavior

Ends… To make the fabric more attarctive, lustrous by

operations like calendering, schreinering, optical whitening.

Modifying the feel of fabric by softening, stiffening, peaching, etc.

To cover faults in the original fabric eg. By starch finishing.

Improving wear qualities of fabric by making it shrink resistant (sanforising cotton or non-felting wool), crease resistant (by incorporating suitable resins), or free from pills and soiling (by anti pilling or soil release finishing)

Ends… To make garments hold their shape and enable them

to be worn without ironing, e.g. Dura Press finishing Imparting special properties to fabric for specific end

uses e.g. water proofing, flame proofing, moth proofing To set the texture of certain fabrics and make others

dimensionally stable e.g. by crabbing of wool, heat setting synthetic fibre fabrics

To produce stronger and more durable fabrics such as seat covers of cars (Coating, Bonding, Laminating)

To produce novelty effects e.g. Organdie fabrics by parchmentising.

Classification of Finishes

Some finishes are routinely given to fabrics before dyeing or final processing but referred to as steps in fabric preparation

Mechanical Chemical Mechanical & Chemical

Classification of Finishes

Permanent e.g. exploiting properties of heat sensitive fibres

Durable Temporary Renewable

Finish Application

Padding - Drying – Curing Efforts to minimise energy spent on

Drying Most expensive part of finishing Low wet pick up techniques Mangles that squeeze of water Suction driers Centrifuges that spin off water before

drying

Drying

Heated Cylinders (not for pile fabrics) Radio frequency Hot Air in a Tentering Machine Hot cylinder drying followed by a

tentering machine.

Fabric Preparation

Spinnability of fibres - Natural Lubrication

Cotton & Cotton Blends

1. Singeing

2. Desizing

3. Scouring

4. Bleaching

5. Mercerization

Fabric Preparation

Silk

1. De-gumming

2. Bleaching Wool

1. Carbonizing

2. Scouring

3. Fulling

4. Bleaching

Basic Finishes: Modifying Appearance Optical Brighteners Delustering

Calendering

Calendering

The domestic Iron Lustre, Compactness, Linen-like

appearance Fabric after wet processing is in the least

lustrous state with highly crimped and wavy threads

Fabric passed between rollers or bowls of a machine termed Calender and this mechanical process is called calendering.

The Machine

1. Soft bowls: Wood, compressed cotton, paper

2. Hard surface bowls: Polished metal like steel, cast iron

3. Heated by steam

4. Geared to prevent slippage

5. One soft bowl against a hard bowl

6. Calender “Nips”

7. Multibowl calender

3, 5, 7 or 10 bowls are used in a multibowl calender arranged in a definite order

GLAZING or Friction Calendering

a) Higher gloss

b) Greater closing up of threads

c) Speed differential: Top bowl – 1.5 to 2 times the speed of lower bowls

d) Generally 3-bowl calender used

e) Bottom bowl: cast iron, Middle: compressed cotton, Top bowl: chilled iron

f) Top & bottom: compressed cotton, Middle: steel for light friction finish

g) 4 bowl: cast iron, cotton, chilled iron, cotton

h) For linings, shirtings, printed cloth, book cloth.

i) Fastness to washing

j) Permanent with resins

Schreiner calender

a. Embossing fine lines

b. Silk finish

c. Principal: lusture of fabrics greatly increased if fibres on the surface are aligned parellel to each other

d. Such embossing achieved by engravings of 50-200 lines per cm

e. Lines not to sharp as to damage cotton

f. 2 bowl, Top steel, lower compressed paper

g. Pressure of 100 tons or more

h. Cotton bowl at a skew to give enhanced brilliancy

i. 3-bowl, paper-engraved-paper

j. Spun Glass finish with Schreinering + Friction calendering

Linings that are not washed

Temporary or permanent finish CIREING:

a) High surface polish

b) Wet Look

c) Natural fabrics given cire effects with waxes or thermoplastic resins

d) Heat sensitive fabics given a permanent cire finish as thermoplastic fibres fuse slightly under heat of rollers.

Surface Finishes

Calendering

1. Simple Calendering

2. Glazing: Friction Calendering, e.g.

3. Cireing: The Wet Look

4. Embossing

5. Schreinering

Basic Finishes: Modifying Hand/Texture Stiffening

1. Sizing

2. Permanent Stiffening of Cottons (Parchmentising)

3. Weighting of silk

4. Softening

Beetling Napping & Sueding Brushing Shearing Flocking Burn out Designs Plisse Designs Acid Designs Enzyme Treatment: Bio Polishing, Enzyme

washing in Denim (Cellulase enzymes)

THE WET LOOK

THE CIRE FABRIC

Suede

Beetled Linen

Raising

Sanforising

Shrinkage, 1st to 5th wash Relaxation shrinkage Compressive Shrinkage Elastic thick blanket-passed over a roller

of a smaller diameter – Outer surface elongates – outer surface > inner surface

Shrinking by an amount of a-b Heat setting for knits-VH-Tric-O-Dry,

Sanfor-Knit

Sanforising Machine

PRINCIPLE

Sanforising

By sanforising, shrinkage by laundering reduced to 0.75 % or less

Marketing cotton & linen garments as non-shrink

Resin treatment for Rayons: Urea-formaldehyde, melamine-formaldehyde

Crease resistant + Non shrink Rayon

Setting of Woollen Fabrics

CRABBING, POTTING, DECATISING

Crabbing

Woolen fabrics contain latent strains or tension developed during spinning , weaving or knitting process. Uncontrolled release of these strains lead to distortions uneven patterns and shrinkage. E.g. crows foot, cockling, uneven shrinkage

Crabbing is a process which eliminates these problems.

Crabbing Fabric wound on a perforated beam under tension so

that tension on the inner part > Tension on the outside Tension to be uniform and not too much No creases Fabric passed in open width through boiling water on a

perforated beam The beam rotates in the boiling water for about 10 mins. Process repeated multiple times Inner surface now becomes outer surface and thus

uniform treatment ensured. Boiling water + dil. Ammonia (at PpH 9.2, max effect of

setting reached)

Crabbing

The cloth is held firmly and tightly to avoid wrinkling

Repetition of the treatment with increased pressure results in setting the cloth and the finish.

Decatizing

Crabbing and potting use boiling water to set the fabric

In Decatising only steam is used This is a process of setting woolen

materials at various stages of the production of woolen fabrics and garments. Essentially this is a stress-relaxation process.

Decatizing

The chemical changes taking place during setting of wool involve thiol-disulhide exhange.

Wool fibres contain a small quantity of thiol group (-SH) which can be increased by reaction of wool , i.e disulhide bond ( -S-S), with a reducing agent or by action of hot water , steam or alkalies

Decating or Decatizing or Blowing Decating or Decatizing is a shrinking

treatment that is sometimes used instead of London Shrinking.

Decatizing is faster and gives reasonable protection against further shrinking. There are two types of Decatizing Dry and wet Decatizing.

Dry Decating If the luster is to be set that fabric is wound

under tension on a perforated roller that is then placed in a preheated equipment (roller) with a vaccum system.

Steam is first forced from the inside of the roller through the layers of fabrics for two to three minutes ; then the process is reversed. The fabric is them removed and cooled by air.

Can be used for cotton, rayon etc.

Wet Decatizing

If the luster is to be increased , the fabric, wound under tension on a perforated roller , is placed in hot water at 140 to 212’F (60-100’C) that is first forced through the roller and fabric and then reversed.

The cloth is then removed cooled with cold water or cold air , and dried.

London Shrinking

This is a superior preshrinking treatments given to better-quality wool fabrics. It is cold-water process by which the cloth is interleaved with wet blankets, dried slowly for twenty four hours , and then set under 3500 pounds per square inch.

Milling

Milling is a process essential in woolen manufacture to give fullness and body to the material. Without milling the fabric will not have good strength and draping quality.

Felting

Felting is the process of making felts from fibers which are formed into a compact mass by pressure , and thus make a fabric without the process of spinning and weaving

Milling

Milling should be regarded as process , and the felting the resulting phenomenon.

Controlled felting is milling.

Fulling or Milling

After the weaving process, woolen and worsted gray goods are placed in warm, soapy water and are pounded and twisted to make the wool fibers interlock . This application of heat moisture and pressure , followed by a cold rinse , is called fulling .

Fulling or Millling

Fulling produces desired shrinkage and gives the fabric additional thickness and a firmer, fuller texture.

The longer the fulling operation , the greater the shrinkage with consequent increase in fabric strength

Milling

Milling is carried out in 3 ways

1. Low grade woollen are milled in grease, because if such material is first scoured, it would loose weight by removal of short length fibers. During the process , cloth is treated with sodium carbonate solution where soap is formed as reaction of fatty acid.

Milling

2. Worsted and high quality woolen are milled with soap and surfactant as foam booster.

3. Acid Milling : Milling in acid ( Sulphuric acid) gives a better cloth without significant cloth damage, cloth may have slightly harsh handle and further softener treatment is required.

Reference

Understanding Textiles: Tortora & Collier Textile Finishing: J T Marsh Textile Finishing: R S Prayag Textile Fiber to Fabric: Corbmann