Monday, December 19, 2016

What is Discharge Printing? | Discharge Printing Methods

Discharge Printing:
In discharge printing the ground color is applied by dyeing or padding with dis-chargeable dyes. It is a very cool technique that removes the dye from the fabric. Discharge printing is like to screen printing process but here instead of normal ink, discharge inks are used. Which remove the fabric’s dye instead of putting a color on top of the fabric or shirt. Discharge printing works best on cotton fabrics because other fabrics are dyed in different processes and react less to discharge chemicals and therefore the dye does not break down.
discharge printing
Fig: Discharge printing on t-shirt
Methods of Discharge Printing:
Basic steps of discharge printing are printing, drying, steaming and washing. This technique is used on dyed fabrics (usually in dark shades). The fabric is dyed in the piece and then overprinted with a discharge paste (chemical) that destroys or decolorizes or changes the color in designed areas. A white discharge is when the original white is restored to the printed area. A color discharge is when a separate color is applied at the same time as the discharge paste. Sometimes the base color is removed and another color is printed in its place; but usually a white area is desirable to brighten the overall design.

This printing method is generally used to obtain designs with tiny details, sharp and well defined edges on colored backgrounds, patterns with low coverage ratio on colored backgrounds, and to avoid pattern matching problems on endless design patterns with colored backgrounds. The results obtained with this printing method could be hardly reproducible with direct printing since it would be very difficult to obtain wide backgrounds, smooth and well penetrated, with sharp edges without seam defects.

A problem for this printing method is represented by the need to choose perfectly destroyable dyes for backgrounds, which cannot be affected by the discharging agent used as brightener. The selection restricts the number of applicable dyes and above all, for some color classes, very few dyes grant a good fastness to light and moisture, but excellent color effects. With this type of printing carried out on black or navy blue backgrounds it is also impossible to check if the various colors are correctly positioned; any mistake will be visible only after the steaming process and at that point it would be impossible to correct it. This problem could be limited by testing the printing result on a white cloth before beginning the printing process.