Printing basic knowledge (2/3)

Methods of Printing
Three different approaches or techniques are prevalent for printing colour on a fabric: Direct, Discharge and Resist
 

Direct Printing
It is the most common approach to apply a colour pattern on fabric. It can be done on white or a coloured fabric. If done on coloured fabric, it is known as overprinting. 
The desired pattern is produced by imprinting 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 corn starch was preferred as a thickening agent for cotton printing. 
Nowadays gums or alginates derived from seaweed are preferred because they are easier to wash out, do not themselves absorb any colour and allow better
penetration of colour. Most pigment printing is done without thickeners as the mixing up of resins, solvents and water itself produces thickening.
 
Discharge Printing
In this approach, the fabric is dyed in piece and then it is printed with a chemical that destroys the colour in the designed areas. Sometimes, the base colour is removed and another colour is printed in its place. The printed fabric is steamed and then thoroughly washed. This approach is on decline these days.

Resist Printing
In this technique, a resist paste is imprinted on the fabric and then it is dyed. The dye affects only those parts that are not covered by the resist
paste. After dyeing, the resist paste is removed leaving a pattern on a dark background.

There are various methods of printing continue here