Knit Fabric Dyeing Process Parameter

Emdadul Haq 

Lecturer, Department of Textile Engineering, Primeasia University; Bangladesh 

Dyeing is a process of coloration of textile fabric by using some required dyes & chemical according to the specified shade, color & order. Dyeing is the aqueous application of dyes on textile substrate. Dyes can be absorbed or adhere on to the substrate in solution form through covalent bond or complexes with salts or metals by chemical retention or physical adsorption. Dyes are of different types & applied to different fabrics like natural or synthetic in different methods. Reactive dyes are most common for cotton fabric dyeing, disperse dyes are widely used for polyester fabric dyeing in the industry & pigments are also used for cotton & CVC fabric dyeing. During dyeing operation, many dyeing parameters such as time, temperature, pH etc. are affected on whole dyeing process.

Knit Fabric Dyeing Process Parameter 

pH 

Scouring (NaOH)	11-12
Bleaching (H2O2)	10.5-11
Enzyme	4.5-4.8
Reactive dyeing	10.5-11.5
Polyester dyeing	4.5-5.5
Disperse dyeing	4.5-5.5
Before dyeing (Levelling)	6.5
Salt	7-8
Softener	6.5

Temperature

Cotton scouring	90 – 120℃
NaOH addition	65℃
H2O2 addition	70℃
Peroxide killing	80℃
Polyester dyeing	100 – 135℃
Polyester stripping	130℃
Bio-polishing	55 – 63℃
Cotton dyeing: Cold brand	45℃
Cotton dyeing: Medium brand	60℃
Cotton dyeing: Hot brand	80℃
Migration for Turquoise color	80 – 90℃
Optical Brightening Agent (OBA)	80℃
Reduction cleaning	80 – 90℃
Softener	55℃

Time

White Fabric	3 – 5 hours
100% Cotton	8 – 10 hours
100% Polyester	3.5 – 5 hours
CVC	13 – 14 hours

 M : L Ratio

Reactive dyeing	1 : 6
Turquoise dyeing	1 : 8
Viscose dyeing	1 : 10
Fluorescent dyeing	1 : 20
Critical shade dyeing	1 : 6

Types of Dosing

👉Linear dosing
👉Progressive dosing
👉Decrease dosing