Handbook on Basic Principles of Textile Processing
Handbook on Basic Principles of Textile Processing of Knitted Fabric
Dedication
This book is dedicated to the cherished memory of my professor, Late C. B. Gupta, whose wisdom, guidance, and passion for textile processing have been a source of inspiration throughout my journey. His unwavering dedication to knowledge and excellence continues to shape my understanding and appreciation of this field. I am forever grateful for his teachings and the invaluable lessons he imparted.
FOREWORD
The manufacturing of textiles is one of the oldest and most important industries of all. Its raw materials are fibres, and the study of textiles therefore begins with an understanding of the fibres from which modern textiles are made. Fibre will be converted to yarn and then yarn to fabric, finally fabric in to garments. In this book, an outline is given of the processing of knitted fabric made from cellulosic fibre. The book has been written for all concerned with the textile trade who require a background of information on manufacturing of knitted fabric to help them in their work. Every effort has been made to ensure that the text is accurate and up-to-date. In writing this book I have been given much encouragement and help by many individuals and organizations.
Introduction
Knitted fabric processing plays a crucial role in the textile industry, ensuring quality, durability, and aesthetic appeal. This handbook outlines the essential principles and techniques involved in the processing of knitted fabrics, from raw material selection to finishing.
Chapter 1: Understanding Knitted Fabrics
1.1 Types of Knitted Fabrics
1.2 Properties of Knitted Fabrics
1.3 Terminology of Knitted fabric
Chapter 2: Pre-Treatment Processes
2.1 Singeing
2.2 Scouring
2.3 Mercerising
2.4 Terminology used in Pretreatment
Chapter 3: Dyeing and Printing
3.1 Dyeing Methods
3.2 Printing Techniques
Chapter 4: Finishing Treatments
4.1 Mechanical Finishing
4.2 Chemical Finishing
Chapter 5: Quality Control and Testing
5.1 Key Quality Parameters
5.2 Standard Testing Methods
Chapter 1: Understanding Knitted Fabrics
What is Knitting –
Knitting is a method by which yarn is manipulated to create a textile or fabric; it is used in many types of garments. Knitting may be done by hand or by machine. Knitting creates stitches: loops of yarn in a row, either flat or in the round. There are usually many active stitches on the knitting needle at one time.
What is the process of knitting-
Knitting is the process of using long needles to interlink or knot a series of loops made by one continuous thread. Each loop or knot connects to another one, and when enough loops have been made, the result is a flat piece of material called a textile.
1.1 Types of Knitted Fabrics
Weft Knitting:
Weft knitting forms loops horizontally across the width of the fabric.
Weft Knitting is basically of two types
Single Jersey
Single Jersey Fabric is knitted on machine which has only Cylinder . It Includes Fabric as Like Single Jersey , Pique, 2 Thread French Terry, 3 Thread Fleece , Sherpa , Twill etc.
Double Jersey
Double Jersey fabric is knitted on machine which has Cylinder and Dial both. So needle runs on both part . In this needles at Cylinder and Dial is at 90 deg to each other. It includes fabric as like1x1 Rib, Interlock, Ponta deroma, Milano rib, 2×2 rib, Verigated rib, Flat back rib etc.
Warp Knitting:
Warp knitting is a method of fabric construction where loops are formed vertically along the length of the fabric, from separate warp yarns. It includes Fabric as like tricot, raschel, and Milanese knits
1.2 Properties of Knitted Fabrics
Knitted fabric has mainly following properties .
Elasticity and stretchability
Air permeability and moisture management
Wrinkle resistance
Comfort and drape
1.3 Terminology of Knitted fabric
In knitted fabric few terminology is being used very commonly . The details about these terminology we will discuss in separate part of series. Here we are discussing only name .
Count – Yarn count for Spun yarn
Denier – Yarn count for filament
Dia- Knitting machine diameter
GG- Knitting machine gauge
Needles- To knit the fabric we use hooked wire known as needle
Sinker – To support loop formation in single jersey machine it is being used
All feeder – If any yarn , which is being used in plaiting in all yarn feeder .
Alternate feeder – If plaited yarn is used in alternate feeder of yarn
Tubular Fabric – If fabric is cylindrical in shape , known as tubular fabric
Open width Fabric – If fabric is cut in knitting or after knitting to make flat , known as Open width .
Falt Knit – If fabric is knitted as like open width without cutting in knitting machine , it is known as flat knit .
Circular knit – If fabric is knitted in circular form in cylinderial machine is known as circular fabric . Now a days we can slit open fabric on circular knitting machine after knitting .
TPI – Twist per inch , For knits yarn is being used of lower TPI than woven
Loop length – The length of yarn used to make one complete loop is known as loop length.
GSM- It is most common word to check the density or thickness of fabric. It means eight of fabric per square meters in Grams .
Chapter 2: Pre-Treatment Processes
Pretreatment means preparation of the fabric for the colouring of fabric by removing impurities of cotton fibre . In the knitted fabric following steps may be used to prepare fabric . It is not necessary to use all steps in all fabric. The selection of steps or sequence of steps can be decided based on product property.
What are impurities in cotton fibre
Cotton fibers naturally contain a variety of impurities, including both natural and added components. Natural impurities are as like proteins, pectin, and coloring matter, And added impurities are as oils, greases, and sizing agents these may be added in subsequent process of spinning, knitting, weaving etc.
2.1 Singeing
Singeing of knitted fabric is a textile finishing process that removes protruding fibers from the fabric surface by burning them off. This treatment improves the fabric’s appearance, reduces pilling, and makes it smoother for dyeing or printing. While singeing is common in woven fabrics. At present it is coming in fashion to use it in knitted fabric also , As it imparts brightness and smoothness more ecological manner . Tubular or Open-width singeing machines are now used to address this issue in knit fabrics, allowing for more even and precise singeing.
2.2 Scouring
Scouring knitted fabric is a crucial pre-treatment process that removes natural and added impurities from the fabric, ensuring optimal dyeing and finishing outcomes. This process makes the fabric hydrophilic and absorbent, which is essential for consistent and even color absorption during dyeing. Scouring can be achieved through various methods, including alkaline solutions, detergents, and enzymes, depending on the fabric type and desired results.
2.3 Mercerising
Mercerization, a treatment for cellulosic fibers like cotton, is applied to knitted fabrics to enhance their properties. It involves treating the fabric with a concentrated solution of sodium hydroxide (caustic soda) under tension. This process increases fiber strength, dye absorption, luster, and improves smoothness
2.4 Biopolish
To remove the loose fibre from the surface of knitted fabric Biopolish treatment is done . It can be done before dyeing, during dyeing or after dyeing . In general now a days during dyeing is preferred method . But for the Heavy weight fabric or stretch fabric for any gsm Biopolish during dyeing is risky process , As it may give rope marks. Specially for dark colours as like Brown, Green, Royal blue . where I always recommend after dyeing bio polish as safe method. It is because the loose lint is get stuck in fabric and being bigger size of dye molecule of Turquise based dyes foams are formed inbetween rope and gives rope marks .
2.4 Terminology used in Pretreatment
The most common terminology used in pretreatment process is
Loading of fabric – To insert fabric in to vessel , where we do pretreatment .
Absorbency – To check the hydroplicity of the fabric by droping water on fabric
Ph – The alkanity of fabric , it is being checked with ph paper or universal indicator . If it goes from orange to red, fabric is acidic. If it goes from green to blue fabric is alkali .
Wicking – The length of water rise in the fabric due to cappaliery action of fibre .
Whiteness Index- It is used to measure the effectiveness of pretreatment process. It gives the indication about removal of natural colour ingredient .
Chapter 3: Dyeing and Printing
Dyeing or Printing means coloration of fabric. The purpose of both process is to make fabric fashionable . Method of dyes in to fabric may vary . And based this method only we say it is dyed fabric or printed fabric .
What is dyeing
Dyeing in textiles is the process of applying color to fabric, yarn, or fiber using a dye in a vessel at particular ph and temperature in the presence of exhaustion and fixation chemicals . This process aims to create a permanent color that doesn’t easily fade or wash out.
What is printing
Textile printing is the process of applying color in a particular pattern known as designs to fabrics using various techniques like roller printing, screen printing, and digital printing. It involves using dyes, pigments, or other chemicals to create patterns on the fabric.
Dyeing Methods
Dyeing is the insertion of colour in to fibre , It can be done by chemical reaction . The reaction need force to push dyes particals inside the fibre . This push may come from chemical or by force ,depending on the nature of push of dyes particals into fire we divide dyeing in to two method broadly , These are below
Exhaust Dyeing
Pad Dyeing
Exhaust Dyeing – In exhaust dyeing dyes is being pushed in to the fibre with the help of chemicals . It is batch process. As it takes time to exhaust dyes in particular ph , temperature and media folloed by fixation of dyes in presence of Alkaline condition at particular temperature within 0- 60 min. based on dyes amount .
Pad Dyeing – Pad dyeing is a textile dyeing method where fabric is passed through a dye bath and then between rollers to squeeze excess dye and ensure even distribution. In this process fabric is passed through colour solution having alkaline media continuously . After that fabric is being holded for 8 hours to fix the dyes on fabric in cold condition. Then it is called as Cold pad batch. While if the fabric is passed through steam to fix the dyes it is known as rapid dyeing, It’s a continuous process, meaning the fabric is continuously moved through the various stages.
Printing Techniques
Textile printing is the process of applying color to fabric in definite patterns or designs.
Types of Printing
There are several types of printing on the basis of that pattern is created on fabric . As like
Direct Printing
Resist Printing
Discharge Printing
Methods of Printng
There are several mode to apply these ink or chemical on fabric based on these mode we can divide print techniues in following types.
Block printing
Screen printing
Rottary Screen
Flat bed screen
Digital Printing
Engraing printing
Stencil printing
Flexo Printing
Heat transfer printing
Chapter 4: Finishing Treatments
Finishing of textile items means making fabric comfortable to end user . It is process hich imparts smoothness , softness , drape , Stiffness dimensionstability to the fabric based on end reuirements.
Mainly finishes can be divided in to two Types
Mechnical Finish
Chemical Finish
4.1 Mechanical Finishing
It is the method where by use of machine only handle or feel and shape of fabric is being changed . In this folloing are the main finishes . Steaming I feel alays the best media to make fabric more stable .
Calendaring
Sueding
Peaching
Raising
Brushing
Compacting
4.2 Chemical Finishing
In chemical finish our purpose is being to make fabric soft , sewable , apply special finishes . Few example of chemical finishes are as below
Silicon soft
Water Repellent
Stain Repellent
Wicing finish
Anti Pilling Finish
Anti curling finish
Antimicrobial Finish
UV protection finish
Aleovera Finish
Malodour absorbant Finish
Chapter 5: Quality Control and Testing
Quality control in any industry is most important part of manufacturing process. In the textile industry it becomes more important as it is the industry where personal involvement is too much. Hence chances of perameter fluctuation is to much . It involves various processes to ensure that products meet specific standards and customer expectations. This includes inspecting materials, verifying dimensions, and assessing fabric properties through testing and visual checks. The goal is to identify and correct defects, maintain consistency, and improve overall product quality. It is designed based on end user requirements and also requirement of next process .
5.1 Key Quality Parameters
Few of the requirements which need to be tested before shipping final fabric to garment industry are as below
Color fastness
Color fastness to washing
Color fastness to water
Color fastness to rubbing
Dry rubbing
Wet rubbing
Color fastness to perspiration
Acid perspiration
Alkali Perspiration
Color fastness to Saliva
Color fastness to dry cleaning
Color fastness to light
Color fastness to Bleach
Dimensional stability
Shrinkage in length and width direction after washing in washing machine and drying based on wash care instruction to be tagged in garment , It has to be tested after one wash and after 3 wash .
Appearance after washing
Bursting strength of fabric
Sewability of the fabric
GSM (Linear density of fabric)
Blend percentage of fabric
Pilling test
Ph Testing
5.2 Standard Testing Methods
Any testing has a meaningful result if and only if it has been tested based on stablsihed method in required atmospheric condition . It is as like that some one say drink one glass water . But what is the standard size of one glass . Same way in textile industry to measure all above defined testing reuirements there are some standard testing methods . These methods are established by some international agencies Few will established brands also have created some testing method with own names.
Below are few of the standard testing procedures
AATCC Standard
ASTM Standard
ISO Standard
JIL Standard
BS Standard
M&S Standard
Conclusion
Textile processing of knitted fabrics involves a series of steps to achieve the desired characteristics and quality. Understanding each stage ensures efficiency, sustainability, and product excellence. For better understanding of each process further handbook of each process will be released .
