Cold-pad-batch and continuous bleaching operate at high alkali concentrations, typically pH 11–13 with caustic soda or soda ash. Standard wetting agents lose surface activity or become destabilized under these conditions, leading to uneven penetration across fabric width. Alkali-resistant anionic wetting agents remain stable throughout the batch rest period, ensuring consistent caustic penetration and uniform scouring results.

Hard water calcium, magnesium, and iron ions each interfere with textile pretreatment in distinct ways:

• Calcium and magnesium precipitate with anionic dyes and auxiliaries, depositing on fabric and equipment surfaces
• Iron ions (Fe³⁺) catalyze cellulose degradation during peroxide bleaching and cause unpredictable dye shade shifts

A dispersing sequestering agent chelates all three before they reach the process bath, protecting fabric integrity and shade reproducibility.

Compared to acid hydrolysis or oxidative chemical desizing, amylase enzymes offer three practical advantages:

• Selectivity: hydrolyze starch sizing without degrading cellulose fiber
• Milder conditions: effective at moderate temperatures and near-neutral pH, reducing energy consumption and fiber damage risk
• Cleaner effluent: produce simpler breakdown products (primarily sugars), lowering the COD/BOD load on wastewater treatment systems

Residual hydrogen peroxide in bleached fabric will oxidize reactive dye chromophores during dyeing, causing unlevel or faded results. Catalase enzymes decompose H2O2 into water and oxygen at neutral pH, completing biological deoxygenation in 10–20 minutes. Unlike reductive neutralization with sodium metabisulfite, catalase requires no additional chemical dosing and eliminates the extended hot-water rinse cycles that increase water and energy consumption.

Co-bath processing integrates degreasing into the dye bath, eliminating a separate scouring step and reducing total machine time in jet and overflow equipment. This requires a degreaser stable at 120–130°C disperse dye conditions without suppressing dye exhaustion or causing unlevel results. Nonionic degreasing agents are generally compatible with the weakly acidic pH range used in polyester disperse dyeing, making them well suited to co-bath use on polyester-cotton blends.