Discharge Printing

Fabrics are dyed a solid color prior to printing. When printing is done, the design is

applied by screen or roller with a chemical which removes the color of the originally

dyed fabric. Discharge prints can be made with rollers and screen methods. They are

not widely used because production costs are high.

Discharge Print

Textile printing is the process of applying colour to fabric in definite patterns or designs. In properly printed fabrics the colour is bonded with the fiber, so as to resist washing and friction.

Textile printing is related to dyeing but, whereas in dyeing proper the whole fabric is uniformly covered with one colour, in printing one or more colours are applied to it in certain parts only, and in sharply defined patterns.

In printing, wooden blocks, stencils, engraved plates, rollers, or silkscreen’s can be used to place colours on the fabric. Colourants used in printing contain dyes thickened to prevent the colour from spreading by capillary attraction beyond the limits of the pattern or design.

Traditional textile printing techniques may be broadly categorized into four styles:

Introduction

Direct printing, in which colourants containing dyes, thickeners, and the mordants or substances necessary for fixing the colour on the cloth are printed in the desired pattern.

The printing of a mordant in the desired pattern prior to dyeing cloth; the color adheres only where the mordant was printed.

Resist dyeing, in which a wax or other substance is printed onto fabric which is subsequently dyed. The waxed areas do not accept the dye, leaving uncoloured patterns against a coloured ground.

Discharge printing, in which a bleaching agent is printed onto previously dyed fabrics to remove some or the entire colour.

Resist and discharge techniques were particularly fashionable in the 19th century, as were combination techniques in which indigo resist was used to create blue backgrounds prior to block-printing of other colours.[1] Most modern industrialized printing uses direct printing techniques.

Introduction

Discharge Printing

Discharge printing is a process where printing of lighter colors is done onto fabrics having darker background. The dye in the garment is removed by replacing it with ink which leaves a soft texture on the fabric. 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.

Initially in discharge printing, the finished goods required steaming during the drying process which discouraged the practicing of this process. But the latest discharge ink systems react chemically and do not require steaming. These latest systems brought advancement and brought new openings in the area of screen printing.

Discharge Printing

The casino table’s graphics are done with discharge printing to avoid the hindrance of the printed line when the dice is rolled. If at all the printing is done with plastisol it would change the speed of the rolling dice. The discharge print gives a smooth run for the rolling of the dice.

Discharge printing produces vibrant, opaque colors on dark color fabrics. The depth, levelness and penetration can be controlled in discharged printing. Complex patterns and soft colors can be produced with immense clarity.Discharge printing is best observed when the four color printing is done on black 100% cotton shirts. The print appears best only when it is exposed to the heat chamber.

Discharge Screen Printing

Discharge Printing

Required Fabric for Discharge Printing Discharge printing enables a clean and transparent print than the earlier discharge addictives which were used only for water base inks. Reduction is the keyword for discharge printing.The method of discharge printing changes from fabric to fabric, but the best fabric for this method is a pure cotton one.

Discharge all over PrintingZinc-formaldehyde is used to remove the dye in the discharge process. Therefore, it is necessary to wash the t-shirts before you wear them. Zinc- formaldehyde free discharge is also available which does not need any washing before wearing it. This is proved to be a better process than the ordinary discharge printing process.Use the right kind of fabric.-      The fabric has to be 100 percent natural like cotton.-      The dye on the fabric should be easily discharged. Cotton gives wonderful results in this process.-      The fabric should be dyed right avoiding over dyeing. This generally happens when there is shortage of dye and therefore another color is dyed on top of this color. So when we try to discharge it, it results in the color which is below it.It is important to check the fabric before starting the process. The fabric should be strong enough to carry the discharge process.

Required Fabric for Discharge Printing

Discharging agents :--Clearly, the most important methods of discharging are based on reduction. This general method can be varied and adapted to give discharges with most classes of dye in use and on most types of fibre. Indeed, to many printers the terms ‘reducing agent’ and ‘discharging agent’ are synonymous.

The most widely used reducing agents are the formaldehyde sulphoxylates. The stability of these compounds is such that only limited losses of sulphoxylate occur during printing and prior to steaming. The use of sodium formaldehyde sulphoxylate (CI Reducing Agent 2, sold as Formosul or Rongalite C) was established as long ago as 1905, when it was recognized that methods based on this reducing agent offered many advantages.

Discharging agents

Conclusion

The discharge printing process is slightly more expensive because of the inks and

chemicals used as well as a slightly more difficult process but the end result leaves

that super soft feel that everyone wants! Works great for oversize designs with a lot of

coverage so when wearing the shirt, you’re not wearing that extra unbreathable ink

since the discharge print is actually part of the garments

Conclusion