Defectively dyed apparel is made into one or more batches to dye with sulfur black dyes.
Process of Cotton dyeing:
- L: R = 1: 10 (for 150 kg)
- 60 kg salt @ 40% of liquor
- Raise temp. to 60º C by steam supply.
- After 15 min add sulfur black @ 12% + Sodium Hydrosulfide @ 14% of liquor
- Raise temp. to 80º C and continue processing for 120 mins.
- Raise temp. to 90º C add Sodium Carbonate @ 5%. Continue processing for 60 mins.
- Reduce dyeing temp. 70º C and drop the dye liquor
- To remember unfixed dye, a hot wash at 50º C with 0.5% detergent for 15 minutes with 1500 liter water. Continue washing for 5 mins without temperature
- Sulfur black-dyed garments if stored, may form sulfuric acid which will reduce garment strength. To avoid this, 3% unidol SF paste may be used.
- Dyeing with sulfur dye is very dirty work for m/c, the floor, operators & environment should be cleaned well for further processing.
Cotton sweater dyeing with pigment:
1. Pretreatment (Bleaching, scouring)
| L :R = 1 : 25Detergent (Filose) @ 0.5 g/LSoda ash @ 2 g/LCaustic Soda @ 3g/L | H2O2 @ 3ml/LTemp = 900C; Time= 40 min |
2. Singeing:
Cellulose (Denimex 992 L)) Enzyme @ 1 g/L
Acetic acid = PH 4.5
Temp. = 550C
Time= 30 min
3. Pigment dyeing:
Cationic agent (Prifix K) 1g/L
Soda ash = PH 8.5
Pigment Red H3BD @ 0.5% anionic pigment forms a bond with cationic cotton
Binder @ 1g/L forms a preliminary net structure with pigment and fabric
4. Washing:
Softener 0.5 g/L
Acetic acid = 5.5 PH
- During drying, the final fixation of the binder takes place.
