Material Composition
Organic and inorganic substances including waxes, pectins, proteins, and minerals constitute the portion of a raw plant fibre that is not pure cellulose. Determining the percentage of non-cellulosic impurities is a mandatory step in assessing the bleachability of a cotton lot.
Removal Process
Scouring in a caustic soda solution targets these specific substances to prepare the fabric for further chemical treatment. If non-cellulosic impurities remain on the fibre, they act as a hydrophobic barrier that prevents water-based dyes from penetrating the core. The efficiency of the scouring bath is measured by the reduction in weight after the removal of these waxes and proteins.
Dyeing Problem
Patchy coloration or low wash fastness often results from residual oils or pectins that were not fully eliminated. When non-cellulosic impurities are present during the dyeing cycle, the pigments may bond to the impurity rather than the cellulose. This bond is weak and easily breaks during home laundering, leading to heavy color loss and staining of other garments.
Chemical Analysis
Weighing a sample before and after a standardized scouring and bleaching protocol determines the total impurity load. Technicians calculate the ratio of non-cellulosic impurities to ensure that the pre-treatment chemicals are dosed at the correct concentrations. This data informs the mill on whether a batch requires a double scour or a more aggressive enzyme treatment to reach the desired level of purity.
