Fabric colouration technique that combines art, engineering & dyeing technology to produce coloured textile substrate. It includes dyeing as well as printing.
Difference between Textile Dyeing & Printing
Dyeing is the uniform coloring of the whole surface of the substrate. Textile dyeing can take place in any textile manufacturing stage. Printing is applying color only to the target areas, thus introducing various colors, patterns, and designs to the textile fabrics. It is also called localized dyeing. The importance of the dyeing and printing process is to enhance the look of the fabric.
Textile Printing Process Flow
It is normally carried out at the fabric stage and sometimes at the garment stage. Fabric printing involves the following steps:
Types of Printing Styles
Fabric can be printed in three different styles: direct, discharge, & resist styles.
• Direct Style
The most common style of printing textile fabric is direct printing. The dye is directly applied onto white fabric or colored fabric. The printed portion is significantly darker than the dyed background. The direct style of printing is used in block printing, screen printing, or roller printing methods.
• Discharge style
Discharge printing in textile is also known as extract printing. It is based on the chemical destruction of the original dye in the printed area. The discharging agents used can be oxidizing or reducing agents, acids, alkalis and various salts. For discharge printing, the ground of the substrate should be dischargeable. It is recommended that dyed discharge fabric should be pre-padded with 2-3 GPL Resist salt. The actual amount of discharging agent requirement for optimum discharge will depend upon:
• The dyes to be discharged
• The depth of the ground
• The fabric being printed.
If no colour is added to the discharge print paste, the result is a white discharge. Discharge is only carried out by reduction. The introduction of sodium sulfoxylate formaldehyde, Pidicron NRT by Pidilite Colour discharge printing in textile can be done by Pigment dispersion on Reactive or Vat dye on the reactive ground.
• Resist style
In the resist style of printing style, RFD fabric is first printed with resist paste which prohibits the penetration of the dye into the fabric. The fabric is then dyed and subsequently, the resist paste is removed & leaving the desired pattern.
Types Of Textile Printing Methods
• Block printing
Block printing is the oldest method of printing that still exists, but the use is limited to the decoration of scarves and handkerchiefs. Colour is applied evenly to the wooden block with different designs & the pattern is stamped on the fabric.
• Roller Printing
It is the most economical and fastest printing. This technique is used whenever long runs of fabric are to be printed with the same design. Engraved printing rollers used one for each colour, press against the fabric and the central cylinder. The printed fabric passes from the main cylinder and through a drying and steaming chamber to fix the colour.
• Screen printing
It is like a photographic process. In this method, the design is applied by passing print paste through a silk or nylon screen on fabric. The screen of a single design is reused for a single colour. Screen printing may be a hand operation or an automatic machine process.
• Heat Transfer Printing
Papers with printing patterns are applied to the fabric and then passed together through a type of hot calendar, and the pattern is transferred from one to the other. This type of printing is very popular for polyester fabrics, especially.
• Digital printing on fabric
Digital printing is a modern age technology with improvements in machines and ink. Digital printing is a growing and non-contact method that deposits tiny droplets onto the specific location of the substrate. It transfers colored ink drops on the fabric substrate using special electrical signals to get unlimited color combinations. In the case of digital printing on textiles, the most used technology is Inkjet. It is a technology in which ink is sprayed through the nozzles onto the substrate. It is further divided as
• CIJ- Continuous inkjet- In this, a small portion of the continuous flow of ink drop is directed onto the fabric in line with the image signal, and the balance unprinted droplets are returned for reuse.
• DOD- Drop on Demand- In these drops of ink are only generated if only the image signal information demands. This is further divided into a) thermal, b) piezo, and c) electrostatic inkjet.
Conclusion
• Direct printing is a preferred technique of textile printing.
• Pigment printing is the easiest and most famous printing technique.
• Discharge and resist printing are preferred for some designs.
• The Digital printing trend is increasing with the improvement in technology.
