1. RESIST PRINTING UNDER REACTIVE DYES
REIST PRINTING: PREVENTION OF DYE FIXATION AT THE PRINTED PORTION
WHITE RESIST: WHITE PRINT AGAINST COLOURED BACKGROUND
COLOURED RESIST: COLOUR PRINT AGAINST COLOUR BACKGROUND
PRINCIPLE
REACTIVE DYES FIXED ON COTTON UNDER ALKALINE CONDITIONS
DYE FIXATION PREVENTED UNDER ACIDIC CONDITIONS
SEQUENCE: PRINT WITH RESISTING AENT > DRY > NIP PAD WITH DYE + ALKALI >DRY > STEAM > WASH > SOAP > WASH > DRY

2. CHOICE OF ACID
INORGANIC ACID SUCH AS HCl NOT SUITABLE DUE TO DANGER OF FIBRE DEGRADATION DURING STEAMING
VOLATILE ORGANIC ACID LIKE ACETIC ACID NOT SUITABLE
NON-VOLATILE ORGANIC ACID LIKE CITRIC ACID, TARTARIC ACID SUITABLE
THICKENER: SHOULD BE STABLE TO ACID e.g. MODIFIED GUAR GUM (INDALCA AGBV)

3. PRINT PASTE COMPOSITION
CITRIC ACID 50 PARTS
WATER ml
THICKENER PASTE 900 PARTS
TOTAL 1000 PARTS
PRINT > DRY
PAD LIQUOR COMPOSITION
REACTIVE DYE g/l
RESIST SALT 10 g/l
SOD. BICRBONATE g/l
NIP PAD > DRY > STEAM FOR MIN. > WASH > SOAP > WASH > DRY

4. COLOURED PRINT AGAINST COLOUR BACKGROUND
COLOURED RESIST
COLOURED PRINT AGAINST COLOUR BACKGROUND
PRINCIPLE:
INCORPORATE DYE/PIGMENT IN RESIST PASTE WHICH CAN BE FIXED UNDER ACIDIC CONDITION
SIMULTANEOUS FIXATION OF GROUND COLOUR AND PRINT COLOUR
PIGMENT ALONG WITH BINDER MOST SUITABLE
PRINT PASTE COMPOSITION
PIGMENT COLOUR PARTS
BINDER PARTS
EMULSION THICKENER 850 PARTS
CITRIC ACID 50 PARTS
TOTAL PARTS
PRINT > DRY > NIP PAD WITH REACTIVE DYE + ALKALI > DRY > STEAM > WASH > SOAP > WASH > DRY

5. DISCHARGE PRINTING UNDER REACTIVE DYES
PRINCIPLE
DISTRUCTION (CHEMICAL DECOMPOSITION) OF DYE AT THE PRINTED PORTION
DISCHARGING AGENT
THERMALLY STABLE STRONG REDUCING AGENT
COMMON DISCHARGING AGENTS
SODIUM SULPHOXYLATE FORMALDEHYDE (HSO2CH2O)Na OR
ZINC SULPHOXYLATE FORMALDEHYDE
(HSO2 CH2O) 2 Zn OR Zn(OH)(HSO2CH2O)
(HSO2CH2O)Na + H2O > CH2OHSO3NA + 2 H
TRADE PRODUCTS
ROGALITE C (BASF), SAFOLITE (TRANSPEK), AROSIT SR (CLARIANT)

6. DISCHARGING AGENTS CALCIUM SULPHOXYLATE FORMALDEHYDE ( RONGALIT H)
STANNOUS CHLORIDE
THIUREA DIOXIDE

7. SEQUENCE
UNDYED FABRIC > DYEING > DISCHARGE PRINTING > DRY > STEAM > WASH > SOAP > WASH > DRY
GROUND COLOURS
CORRECT CHOICE OF DYES IS VERY IMPORTANT IN DISCHARGE PRINTING
SUITABLE DYES USUALLY CONTAIN N=N GROUP WHICH IS READILY ATTACKED BY REDUCING AGENTS GIVING COLOURLESS WATER SOLUBLE AMINES
R-N==N-R’ > RNH2 + R’NH2
INFORMATION RELATED TO EASE OF DISCHARGEABILITY IS NORMALLY GIVEN IN MANUFACTURERES SHADE CARDS

8. COLOURED DISCHARGE
DYES STABLE TO REDUCING AGENT AND THOSE CAN BE FIXED DURING STEAMING IN PRESENCE OF REDUCING AGENT ARE INCORPORATED IN DISCHARGE PASTE
VAT DYES ARE MOST SUITABLE

9. WHITE DISCHARGE GLYCERINE 10-20 PARTS REDUCING AGENT 30-150 PARTS
ZnO/TiO PARTS
WATER PARTS
OPTICAL BRIGHTENER 10 PARTS
BRITISH GUM TO MAKE 1000 PARTS
THIKENER PASTE
PRINT ON DYED FABRIC > DRY > STEAM FOR 30 MIN > WASH > SOAP > WASH > DRY

10. COLOUR DISCHARGE VAT DYE 50-100 PARTS Na2CO3/K2CO3 30-40 PARTS
Zn/Na SULPHOXYLATE
FORMALDEHYDE PARTS
GLYCERINE PARTS
WATER PARTS
BRITISH GUM
THICKENER PASTE TO MAKE 1000 PARTS
PRINT ON DYED FABRIC > DRY > STEAM 30 MIN. > WASH > OXIDIZE > WASH > SOAP > WASH > DRY