Discharge Prints are fabrics which are dyed prior to printing. Many pleasing effects can be obtained by producing coloured patterns on coloured fabrics or by producing a white pattern on a coloured fabric.
Discharge prints are Prints that have a dark background, widely spaced motifs, and a rich, vibrant, expensive look.
For the fabrics to be discharge Printed, the fabric is first piece dyed.
A discharge Paste which contains chemicals to remove the colour on the fabric is then applied to fabric with rollers.
This discharge paste contains a chemical (sulfoxylate-formaldehyde) discharging agent capable of attacking the dye locally.
This chemical is capable of reducing the dye in the fabric, causing the dye to loose its ability to selectively absorb and reflect light. So that finally it shows a white or light pattern on a coloured background.
A second dye resistant to the discharging agent can be incorporated in the paste so that the cloth printed with it yielding a two colour pattern.
A great disadvantage of discourage printing is that a white (or) coloured pattern can be produced on dyed backgrounds.
It enables production of coloured blotches with sharp outlines, generally difficult to obtain by direct style.
This process produces almost the same white (or) coloured discharge effect on both sides of the cloth so that it becomes difficult to distinguish the printed side from the other.
The limitation of discharge type of Printing I that only those colours which can be discharged have to be used since all colours are not dischargeable.
One class of dyes, vat dyes are not affected by the colour destroying chemical.
Identification:
The identification of discharge prints is usually accomplished by inspecting the back of the fabric for small specks of background colour under the design motif. (Specks are the results of the incomplete removal of the background colour by the reducing agents)
Discharge Prints can be made with roller and screen methods, but not by heat transfer printing.
A fabric is said to be of discharge print only if the background colour is same on face and back of the fabric, and the print design area is of white (or) different colour or shade than the background, motifs of discharge prints may range from simple Polka dots to very intricate patterns.
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