Steam Discharge Prints
The discharge process happens when a special combination of resist and bleach is printed into a ready-dyed fabric enabling the original colour to be removed and replaced simultaneously.
In the discharge method of printing, fabric is often dyed in the piece and then printed with a chemical that will destroy the colour in designed areas. Sometimes the base colour is removed and another colour printed in its place, but usually a white area is desirable to brighten the overall design. The usual method of producing discharge prints is to print the design, such as polka dots, with a paste containing caustic soda and sodium hydrosulfite. A steaming follows and then there is a good washing to remove the by-products of the reaction.
The mordant process is called the discharge process. Here the cloth is prepared with various mordants so that when it is immersed in a dye bath, the reaction produces different colours on the cloth. Only those portions which have been prepared take the dye. Various deep shades of great brilliance are produced by the variable use of mordant. Alizerine is the colouring substance of mordant. In the current discharge process, cloth is dyed in the desired background colour from those portions where chemicals have been applied. The discharge parts of the design are then further processed. Depending on the class of the dye and the style of printing employed, the printed and dried cloth is steamed.