Dyeing Methods and Application Techniques
This domain tests how a dye is delivered to fabric: batch, continuous, garment and hand methods, and the controls that make each repeatable.
Core rules
- Exhaust dyeing is batch dyeing from a bath. The material circulates in the dye liquor, and exhaustion depends on time, temperature, salt and liquor ratio.
- Pad dyeing passes fabric through a dye liquor and squeeze rollers, then fixes by steam, heat or batch storage. It suits continuous production.
- Pad-dry-cure is common for pigment and reactive dyeing of piece goods.
- Yarn dyeing gives solid or striped effects; garment dyeing allows late colour decisions but risks shrinkage and creasing.
- Hand methods include tie-dye, batik, block printing and screen printing. They rely on resists, thickeners and careful fixation.
Worked example
A cotton T-shirt is to be tie-dyed. Reasoning: cotton needs scouring before dyeing, and the ties must be tight to resist dye penetration. Wet the shirt, tie it, apply reactive dye, add alkali to fix, leave for the recommended time, then rinse cold, wash hot and neutralise. Skipping the scour or the alkali gives pale, unstable colour.
Traps that cost marks
- Dyeing dry fabric, which takes colour unevenly.
- Using too little alkali with reactive dye and getting poor fixation.
- Squeezing a tied bundle and blurring the pattern.
- Omitting the final soaping and rinsing step.