Printing Introduction

    The colour designs are developed on fabrics with dyes and pigments in paste form with specially  

     designed machines, this process is known as “Textile Printing”. Printing is used to apply colour only on localized areas. i.e. Localized Dyeing. Printed fabrics, usually have clear-cut edges in the printed portions on the face of the fabric. 

               Printing allows

§  Flexibility in creating designs

§  Enables the creation of relatively inexpensive patterned fabric.

Stages of Textile Printing

            The printing process does involve several stages in order to prepare the fabric and printing paste, and to fix the impression permanently on the fabric:

     Pre-treatment of fabric:- Grey cloth as woven on a loom is quite unattractive and contains natural and added impurities, which impart undesirable properties to the cloth and which hinder the successful carrying out of the subsequent dyeing, printing, and finishing processes.

So, in order to prepare the grey fabric for printing, various pretreatment has to be done, like – singeing, desizing, scouring, bleaching etc.

     Preparation of colours:- Water soluble dyes are dissolve in low amount of water to add in printing paste, while disperse dyes are added in dispersion form.

    Preparation of printing paste:- For Printing, the thickened paste is used for sharp boundaries of colour. This objective is achieved by using suitable thickeners and other ingredients, which are necessary for fixation. 

    Impression of paste on fabric using printing methods:- An impression may be made on a fabric using the printing paste by any of the printing methods, such as block, stencil, roller, screen (flat-bed & rotary)

       Drying of fabric:- After the printed cloth leaves the machine, it is passed through hot air or steam, to dry the cloth. This drying is essential to prevent any spreading of the colour beyond the boundaries of the design.  

     Fixing the printing with steam or hot air (for pigments):- When the cloth is printed and dried, the dye is not actually transferred into the cloth. In order to bring about the transfer of the dye into the fabric as much as possible, steaming is carried out.

    After process treatments:- When the printed cloth leaves the steaming chamber, it contains the exhausted thickener film, along with certain chemicals dispersed in it. Therefore, to remove the thickener as well as chemicals after process treatments is done without affecting dyes.

Fabric Requirements for Printing

            For proper printing the following are the general requirements of fabrics

ð  The fabric should be stitched with proper face on top and uniform width.

ð  Shearing and cropping treatment is given to remove loose threads.

ð  Desizing is necessary, for proper penetration of the print paste.

ð  Singeing removes hairy fibres, to enable even adhesion of printing paste and sharpness.

ð  Scouring gives better dye absorption.

ð  Mercerization is given for cotton fabric and heat setting for synthetics.

ð  Full bleach is suitable for whiter background.

ð  The fabric should be thoroughly dried.

ð  It should be free from creases, and should be free from weft bowing.  

Difference between Textile Dyeing and Textile Printing

Textile Dyeing		Textile Printing
1.	Only mono colour application can be done	1.	Mono or multi-colour application is possible
2.	Uniform colouration along length and width of fabric	2.	Localized dyeing
3.	Dyes are applied in liquid form	3.	Dyes are applied with pastes
4.	Water plays an important role in dyeing	4.	Thickening agent plays an important role in printing
5.	Percentage shade is calculated on the weight of the material	5.	Percentage shade is calculated on the weight of the paste
6.	The fabric is handled either in open width or in rope form	6.	The fabric is handled only in open width form
7.	During dyeing, the fabric may be wet or dry condition	7.	During printing, the fabric is to be kept in dry condition
8.	Colour is applied uniformly on both faces of the fabric	8.	The printed face will be darker, and the other face will be paler
9.	Simple machineries are used, such as tanks, winches, jiggers, soft flow, padding mangles	9.	Machineries are more complex, by way of design, screen preparation, printing machines, after process machineries
10.	Cost of dyeing per meter is lower than the cost of printing	10.	Cost of printing per meter is higher than the cost of dyeing