What Is Textile Bleaching?
Bleaching is a textile pretreatment process used to remove or reduce natural colouring matter and improve the whiteness of textile materials. It is especially important when fabric will be dyed in light shades or printed with colours that require a clean and uniform base.
Why is bleaching carried out?
Natural cotton contains impurities such as waxes, pectins and colouring matter. Scouring helps remove many non-cellulosic impurities, while bleaching reduces residual colour. The two processes may be combined or carried out separately depending on the material and process route.
Common bleaching agents
Hydrogen peroxide is widely used for cotton bleaching. Other systems may be used for specific fibres and applications. The correct chemistry depends on fibre sensitivity, machine type and environmental requirements.
Important process controls
Monitor pH, temperature, time, chemical concentration and water quality. Excessive treatment can damage cellulose and reduce fabric strength. After bleaching, evaluate whiteness, absorbency, residual peroxide where relevant and fabric strength according to the mill's test plan.
FAQs
Does bleaching make fabric stronger? No. It improves whiteness but excessive treatment can reduce strength.
Is bleaching always required before dyeing? No. The need depends on fibre, shade and product requirements.
Why is neutralisation or rinsing important? It helps remove or control residual chemicals before the next process.
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