Textile Dyeing, Processing & Chemical Finishes Quiz: Dyes, Stenters & RFD

From Grey Fabric to Finished Cloth

Loom-state greige (grey) fabric contains natural fats, starches, wax, and warp sizing chemicals. It must undergo continuous chemical and thermal processing before it can be dyed, printed, or cut into garments.

Key Pre-Treatment Steps

• Desizing & Scouring: Removing warp starches and natural impurities using enzymes and alkali so the fabric becomes evenly absorbent.
• Bleaching: Whiten natural fibers using hydrogen peroxide to eliminate the yellowish cast, producing RFD (Ready for Dyeing) fabric.
• Mercerisation: Treating cotton under tension with concentrated caustic soda (NaOH) to swell flat fibers into round tubes, enhancing tensile strength, dye uptake, and luster.

Dyeing Chemistry: Matching Dyes to Fibres

• Disperse Dyes: The only class of dyes capable of penetrating synthetic fibers like polyester. Applied under high temperature and pressure (130°C) inside jet dyeing machines.
• Reactive Dyes: Form a permanent covalent chemical bond with cellulosic fibers such as cotton, viscose rayon, and linen, offering superior wash-fastness.
• Acid Dyes: Used primarily on protein fibers like wool and pure silk, as well as polyamide (nylon).

Thermal Finishing: The Stenter Frame

The stenter (tenter) is the backbone machine of a textile process house. It grips the fabric selvedges on pin or clip chains through a heated oven to dry the fabric, equalize width, set fabric GSM, correct bowing/skewing, and cure chemical softeners.

Learn more about process houses in Pandesara and Sachin GIDC in our Surat textile market guide.