blekningen

Blekningen is the bleaching process in textile finishing, used to whiten fabrics and remove natural impurities from fibers before dyeing or printing. The term comes from the Scandinavian word blekning, meaning bleaching, and is used in Swedish, Norwegian, and Danish to refer to this industrial operation.

Chemically, blekning can involve chlorine-based agents such as sodium hypochlorite, or alternative oxidizers such as hydrogen peroxide or oxygen-based bleaches. Physical methods like sun exposure can also contribute in some contexts, especially for natural fibers. The choice of method depends on fiber type, desired whiteness, and fabric strength.

Typical production sequences include scouring to remove oils, the bleaching step itself, thorough washing, and neutralization or buffering to restore fiber pH. Hydrogen peroxide bleaching is common in modern mills owing to its relatively lower environmental impact and its compatibility with cellulose fibers; chlorine-based methods are increasingly restricted due to environmental concerns.

Environmental and health considerations include wastewater treatment, formation of chlorinated organics with some chlorine-based processes, and worker exposure. Regulations in many jurisdictions encourage closed-loop systems, effluent treatment, and the use of less aggressive chemistries.

History and trends: traditional sun bleaching was used for centuries with lye or alkali; the industrial adoption of chlorine bleaching in the 19th century increased whiteness levels, followed by peroxide bleaching in the 20th century as a more sustainable option. Current research includes enzyme-assisted bleaching and ozone-based approaches for certain textiles.

See also: textile finishing, bleaching agents, hydrogen peroxide.