Substrate Transformation
Aqueous chemical treatment alters cotton and viscose fibers through sequential baths that remove impurities and fix colorants during fabric manufacturing. Industrial cellulosics wet processing includes scouring, bleaching, Mercerization, dyeing, and chemical finishing steps applied to continuous tow, woven webs, or knitted structures. The scope of these operations begins with raw grey fabric preparation and concludes prior to mechanical garment assembly.
Treatments cease when the substrate reaches specified pH and moisture content targets required for final cutting.
Alkaline Preparation
Alkaline scouring hydrolyzes natural waxes and pectin substances contained within natural fiber matrices. Highly concentrated sodium hydroxide baths expand cellulosics wet processing efficiency by opening fiber pore structures and increasing internal surface area available for dye uptake. Mercerization under tension realigns crystalline cellulose regions, which boosts tensile strength and increases light reflectivity across finished woven goods.
Color Application
Dyeing operations utilize reactive, direct, or vat dyestuffs suspended within aqueous liquor baths. Reactive dyes form covalent bonds with hydroxyl groups on the cellulose polymer chain during cellulosics wet processing when salt and alkali force dyestuff out of solution. Precise temperature control prevents premature hydrolysis of reactive groups, which would otherwise reduce fixation yields and increase effluent washing requirements.
Rinsing Parameter
Washing sequences remove unfixed dye molecules and residual bath chemicals from processed goods. Multiple hot overflow rinses lower liquor conductivity, stabilizing fastness properties and preventing cross-stain bleeding during subsequent garment laundering. Bath neutralization using dilute acetic acid completes cellulosics wet processing by neutralizing residual alkali bound within dense yarn structures.
