Greige Storage Conditions Impact on Subsequent Dye Absorption
Uncontrolled greige storage triggers moisture migration, lipid autoxidation, and sizing retrogradation, which impair surface wettability and cause severe dye absorption variances.
Alpha-Amylase Degradation
Enzymatic Desizing
Biochemical hydrolysis of starch-based sizing agents on woven fabrics converts insoluble starches into soluble dextrins that are easily washed out. This specific enzymatic action, termed alpha-amylase degradation, targets the alpha-one-four glucosidic bonds in amylose and amylopectin molecules. The process operates exclusively on natural starch sizing and does not affect synthetic polymer sizes like polyvinyl alcohol.
It ceases to function if the temperature exceeds eighty degrees Celsius or if the pH rises above seven.
Hydrolysis Mechanism
The enzyme binds to the starch chain and rapidly cleaves random internal bonds to reduce the viscosity of the sizing film. This action softens the protective warp coating so that it can be removed in a subsequent hot wash. Mill operators monitor this enzyme activity by measuring the viscosity reduction of the wash water.
Efficient desizing prevents dye resist spots in the finished fabric.
Process Parameter
The reaction requires the presence of calcium ions to stabilize the enzyme structure at elevated temperatures. Calcium chloride is frequently added to the bath to maintain enzymatic efficiency during continuous pad-batch processing.
Cleanliness Verification
Residual starch on the desized fabric is checked using an iodine spot test. The presence of a blue-violet color indicates incomplete enzymatic degradation of the size.