Definition of Textile Printing?
Printing is the localized dyeing of textiles. Textile printing is the process of applying color to the fabric in definite patterns or designs. It is a part of wet processing, which is carried out after pretreatment of fabric or after dyeing. It is done for producing attractive designs on the fabric.
Styles of Printing in Textile:
There are many different styles of printing in textile depending on the print design and the final appearance of the printed fabric. Some prints are produced on a white (undyed) background; other print designs require the print to have a colored background. The colored background may be applied to the fabric before dyeing using either a batch or continuous dyeing process. There are also print designs that are printed on blend fabrics containing two different fibre types. Certain printing techniques can be employed to remove (burn out) one of the fibers in the blend to create an almost three‐dimensional print. Common styles of printing in textile are point out below.
- Direct style of printing
- Discharge style of printing
- Mordant style of printing
- Resist style of printing
- Overprinting style
- Flock Style of Printing
- Pigment printing style
Above styles of printing in textile are briefly described below:
1. Direct style of printing:
Direct style of printing, in which colorants containing dyes, thickeners and the mordants or substances necessary for fixing the color on the cloth are mixed to make printing paste and printed on the fabric in the desired pattern. Direct style of printing is probably the simplest printing technique. This style of printing produces a colored print on a white background with each color of the design requiring a separate screen.
2. Discharge style of printing:
In discharge printing, a textile fabric is first dyed with a suitable dye and then the dye is selectively destroyed from certain areas of the fabric to give the look of a printed pattern. In ‘white’ discharge printing, the fabric is piece dyed, then printed with a paste containing a chemical that reduces the dye and hence removes the color where the white designs are desired. In ‘colored’ discharge printing, a color is added to the discharge paste in order to replace the discharged color with another shade.
There are certain disadvantages to this style of printing. The choice of reducing agent depends upon the fiber being printed and the dyes used for the background. The background dyes need to be relatively easy to discharge, so they tend to be azo‐based colours. However, dyes with specific structural characteristics are more easily dischargeable than others.
3. Mordant style of printing:
Mordant style of printing, in which the fabric is printed with one or more mordants in the desired pattern prior to dyeing of cloth; the color adheres only in portions where the mordant was printed.
4. Resist style of printing:
Resist printing, also known as reserve printing. In resist printing, the fabric is first printed with a resist agent and then dyed. On dyeing, the fabric attains color only on areas where resist agent is not present. After dyeing, the resist agent is removed and the fabric gives the look of a printed pattern.
However, the resist printing route allows the use of a wider range of dyes that can be used in discharge printing. There are two types of resist printing technique depending upon how the resist is achieved:
- Mechanical resist, which is achieved by using materials such as resin, clay or wax (African batik prints). These form a physical barrier between the fabric and the dye and are used mainly for coarse decorative styles.
- Chemical resist printing, where the fabric is printed with the resist paste followed by overdyeing, either by batch or continuous methods. The resist paste prevents fixation or development of the ground color by chemically reacting either with the dye or with the reagents necessary for the fixation of the dye. For example, the use of an acid will prevent the fixation of a reactive dye to a cellulosic substrate. The resist agent is applied prior to dyeing and can be used to achieve a white or colored resist if a dye is incorporated within the resist paste. The dye must not be susceptible to the chemicals used in the resist paste in order to produce an illuminating color.
5. Overprinting style:
In the direct printing, a common approach is to apply a color pattern onto a grey or bleached fabric. If done on colored fabric, it is known as overprinting. The desired pattern is produced by pressing dye on the fabric in a paste form. To prepare the print paste, a thickening agent is added to a limited amount of water and dye is dissolved in it. Earlier starch was preferred as a thickening agent for printing. Nowadays, gums or alginates derived from seaweed are preferred as they allow better penetration of color and are easier to wash out.
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6. Flock style of printing:
Flocking is the technique of depositing many small fibre particles, called ‘flock’, onto a surface of a fabric to produce the design. These particles of fibre are stuck by means of a strong adhesive which is water-resistant so as to make it washable. The process involves applying an adhesive in the desired design, adhering short fibers to the fabric, creating a velvety or raised texture. Flock printing adds a luxurious, tactile element to textiles, increasing the visual and sensory appeal of the final product. This method is popular for its ability to produce unique, textured designs on various materials, contributing to the versatility and aesthetic richness of printed fabrics.
7. Pigment printing style:
Printing is done by the use of pigments instead of dyes. The pigments do not penetrate the fiber but are affixed to the surface of the fabric by means of synthetic resins which are cured after application to make them insoluble. The pigments are insoluble, and application is in the form of water-in-oil or oil-in-water emulsions of pigment pastes and resins. The colors produced are bright and generally fat except for crocking. Most pigment printing is done without thickeners because the mixing up of resins, solvents and water produces thickening anyway.
Resist and discharge techniques were particularly fashionable in the 19th century, as were combination techniques in which indigo resist was used to create blue backgrounds prior to block-printing of other colors. Modern industrial printing mainly uses direct printing techniques.
References:
- Principles of Textile Printing by Asim Kumar Roy Choudhury
- An Introduction to Textile Coloration: Principles and Practice By Roger H. Wardman
- Handbook of Value Addition Processes for Fabrics By B. Purushothama
- Textile Engineering – An Introduction Edited by Yasir Nawab
