Textile bleaching processes (overview)
Also known as: Textile bleaching, Bleach process
Umbrella term for all chemical processes that remove natural yellowness or foreign shades from raw fabric — the basis for subsequent dyeing; hydrogen peroxide processes now dominate.
Description
Unbleached cotton, linen or wool contains natural pigments, pectins, waxes and impurities that give the raw fabric a yellowish or greyish cast. Bleaching destroys these chromophores oxidatively or reductively, making the fibre white, uniform and ready to take on lighter shades in dyeing. Three chemistries dominate industrial practice today:
Hydrogen peroxide (H2O2), at around 60 % of world textile-bleach consumption, is the most important bleach — it oxidises at 90–98 °C in an alkaline bath with stabilisers such as sodium silicate; it is environmentally acceptable and leaves few residues. Sodium hypochlorite (NaOCl, classic chlorine bleach) is cheap and effective but is being replaced due to AOX pollution and fibre damage. Sodium chlorite (NaClO2) works well for polyester and polyamide, but operates under acidic conditions and requires corrosion-resistant equipment. Sensitive fibres (wool, silk, viscose) are reductively bleached with sodium dithionite or sulphur dioxide. Optical brightening agents (OBAs) enhance perceived whiteness by absorbing UV and re-emitting in the visible blue. Whiteness is measured using the CIE formula.
- H2O2: dominant process, alkaline, 90–98 °C, environmentally friendly
- NaOCl: classic chlorine bleach, cheap, AOX burden, declining
- NaClO2: acidic, for synthetics, corrosive
- Reductive bleach: wool/silk with sodium dithionite
Properties
| Purpose | Remove natural pigments, produce whiteness, prepare for dyeing |
|---|---|
| Dominant chemistry | Hydrogen peroxide (~60 % world consumption) |
| Reductive bleach | Sodium dithionite for wool, silk, viscose |
| Whiteness measurement | CIE whiteness formula, often augmented by OBAs |
Related product categories
Sources & references
2- Wikipedia: Bleaching of textiles Wikipedia — Freie Enzyklopädie https://en.wikipedia.org/wiki/Bleaching_of_textiles
- TEGEWA: Textile Auxiliaries tegewa.de https://www.tegewa.de/
