Discharging Printing is also called Extract Printing. This is a method of applying a design to dyed fabric by
printing a color-destroying agent, such as chlorine or hydrosulfite, to bleach out a white or light pattern on
a dye impervious to the bleaching agent is combined with it, producing a colored design instead of white on
the dyed ground

Discharge printing has been around for decades. But only in the past 7-8 years screen printers in the
industry have recognized it seriously. In the early years of discharge printing, the finished discharge print
needed to be steamed during the drying process. This discouraged the use of discharge systems in the
finished garment area. The newly developed discharge ink systems are chemically reactive and don't need
to be steam-neutralized. This advancement opened the door to discharge printing for the average screen
printers.

Discharge printing has the ability to make bright,opaque colors on dark fabrics with soft hand. Years ago
the idea of opaque colors on dark fabrics and soft hand couln't co-exist.

Successful light-on-dark printing with plastisol relies on increased pigment loads, fillers and other additives
to block out the color of the garment. Discharge inks modify the garment color by removing the garment color and replacing it with the new ink color. In sampleterms,the discharge ink"bleaches"out the dye in the garment,thus allowing the pigment in the ink to absorb into the shirt fibers.

The real magic of discharge printing can be witnessed when printing four-color process on black 100% cotton shirts. The print before curing appears very trasparent. One can barely see the print until the garment exits the oven chamber,where the results can be quite remarkable: bright,vivid colors with a soft hand feel.

The graphics on the casino gaming tables are printed with dischage inks to avoid the interference of the printed line with toe roll of the dice. If the ink on these tables were printed with plastisol, the ink film (because it is a surface print) would change the speed and direction of the dice, thus changing the way the dice land. Discharge ink, on the other hand, provides a dyed in the fabric result,keeping the playing surface smooth. The decrease in the production time is the biggest bonus of all. The fact that you can skip flash curing cmpletely saves hours of production time and elimanates registration problems between the designs colors and the white printer under base used in normal printing on blacks.

However,flash during can be used in conjuction with discharge printing when printing discharge as an under base.

Cleaner and more transparent inks can also be printed onto dark garments with the help of discharge additives. Early dischage additives were designed only for water base inks, but plastisol additives are available.

Characteristics that indicate a garment will wrk with dischage ink

• The garment has to be made of natural fibers ( 100% Cotton )
• The dye used in the garment must be dischargeable. The best results are achieved with garments that are 100% Cotton and dyed with a reactive dye.
• The garment should not have been over dyed (when fabric is re-dyed to another color). This often happens because of a shortage of a certain fabric color or, in many cases,because quality control rejected the fabric color. These rejected colors are then over dyed with a black dye,which will bring nightmares to life when trying to use discharge inks. The discharge ink might discharge the black dye- only to reveal a phantom color underneath.