Printing basic knowledge (3/3)

There are various methods of printing in which one of the above three techniques is used - Block Printing, Roller Printing, Duplex Printing, Stencil
Printing, Screen Printing, Transfer Printing, Blotch Printing, Jet Spray Printing, Electrostatic Printing, Photo Printing, Differential Printing, Warp
Printing, Batik Dyeing, Tie Dyeing, Airbrush (Spray) Painting and Digital printing
 
Block Printing
The designs are carved on a wooden or metal block and the paste dyestuff is applied to the design on the face of the block.
The block is pressed down firmly by hand on the surface of the fabric.
 
Roller Printing
In this machine counterpart of block printing, engraved copper cylinders or rollers are used in place of handcarved blocks. With each revolution of
the roller, a repeat of the design is printed. The printed cloth is passed into a drying and then a steam chamber where the moisture and heat sets the
dye.
 
Duplex Printing
Printing is done on both sides of the fabric either through roller printing machine in two operations or a duplex printing machine in a single operation.
 
Screen Printing
It is done either with flat or cylindrical screens made of silk threads, nylon, polyester, vinyon or metal. The printing paste or dye is poured on the screen and forced through its unblocked areas onto the fabric. Based on the type of the screen used, it is known as 'Flat Screen Printing' or 'Rotary Screen Printing'.

Stencil Printing
The design is first cut in cardboard, wood or metal. The stencils may have fine delicate designs or large spaces through which colour is applied on the fabric. Its use is limited due to high costs involved.

Transfer Printing
The design on a paper is transferred to a fabric by vaporization. There are two main processes for this :Dry Heat Transfer Printing and Wet Heat Transfer Printing. 
In Conventional Heat Transfer Printing, an electrically heated cylinder is used that presses a fabric against a printed paper placed on a heat resistant blanket. In Infrared Heat Vacuum Transfer Printing, the transfer paper and fabric are passed between infrared heaters and a perforated cylinder which are protected from excessive heat by a shield. The Wet Heat Transfer Printing uses heat in a wet atmosphere for vaporizing the dye pattern from paper to fabric.

Blotch Printing
It is a direct printing technique where the background colour and the design are both printed onto a white fabric usually in a one operation. Any of the methods like block, roller or screen may be used.

Airbrush (Spray) Painting
Designs may be hand painted on fabric or the dye may be applied with a mechanized airbrush which blows or sprays colour on the fabric
 
Electrostatic Printing
A dye- resin mixture is spread on a screen bearing the design and the fabric is passed into an electrostatic field under the screen. The dye- resin
mixture is pulled by the electrostatic field through the pattern area onto the fabric.

Photo Printing
The fabric is coated with a chemical that is sensitive to light and then any photograph may be printed on it.

Differential Printing
It is a technique of printing tufted material made of yarns having different dyeing properties such as carpets. Upto a ten colour effect is possible by careful selection of yarns, dyestuffs and pattern.
 
Warp Printing
It is roller printing applied to warp yarns before they are woven into fabric.
 
Tie Dyeing
Firm knots are tied in the cloth before it is immersed in a dye. The outside of the immersed portion is dyed but the inside is not penetrated. There are various forms of Tie dyeing like Ikat Dyeing where bundles of warp and/ or weft yarns are tie dyed prior to their weaving. In Plangi Dyeing the gathered, folded or rolled fabric is usually held with stitching to form specific patterns.

Batik Dyeing
It is a resist dyeing process. Designs are made with wax on a fabric which is then immersed in a dye. The unwaxed portion absorbs the colour.
 
Jet Spray Printing
Designs are imparted to fabrics by spraying colours in a controlled manner through nozzles.

Digital printing
In this form of printing micro-sized droplets of dye are placed onto the fabric through an inkjet printhead. The print system software interprets the data supplied by a cademic_Textiledigital image file. The digital image file has the data to control the droplet output so that the image quality and color control may be achieved. 

This is the latest development in textile printing and is expanding very fast. Digital Textile Printing