In the washing and dyeing process of denim products, once spandex degradation occurs and results in elasticity loss, such damage is basically irreparable. Therefore, pre-production sampling and testing are essential to guarantee no quality defects during mass production. Based on the physical and chemical properties of polyurethane fibers, elasticity loss of stretch denim containing spandex during washing is mainly caused by improper processing formulas or operation procedures, which lead to spandex breakage, dissolution and other deterioration phenomena, ultimately resulting in lost elasticity.
During the rinsing process, spandex has poor resistance to chlorine bleaching agents. Chlorine-nitrogen bonds form in hypochlorite solution and damage fibers, with even more severe deterioration occurring to polyether-type spandex. Excessively high water temperature or prolonged rinsing duration inside the dye vat will also trigger spandex degradation and subsequent fabric elasticity loss. Accordingly, the following measures are proposed to avoid elasticity loss during rinsing:
- Conduct comprehensive pre-production testing.
- Bleaching water must be fully formulated and mixed before being added into the vat; direct addition of raw chemicals is prohibited.
- Bleaching water shall be added only when the equipment is in running state to prevent localized high concentration from inducing elasticity loss.
- Residual bleaching agent on garments will release chlorine during high-temperature drying and cause spandex degradation. Sufficient post-bleaching rinsing must be carried out thoroughly.
- Strengthen on-site operator management and production monitoring to prevent quality issues caused by overrun processing temperature or duration exceeding technical specifications.
With such high risks of elasticity loss, many practitioners wonder whether there is an effective solution to prevent spandex elasticity loss during rinsing. The answer is affirmative. Novozymes cold bleaching enzyme solution can completely resolve elasticity loss problems in the rinsing process. This cold bleaching enzyme only acts on indigo color to achieve bleaching effects without causing any damage to other fibers, making it highly suitable for bleaching treatment of elasticity-sensitive denim fabrics.
Post time: Apr-23-2026