Scouring & Bleaching Chemicals

Scouring and bleaching chemicals prepare greige (loom-state) fabric for dyeing by removing natural waxes, oils, and seed-hull impurities, then whitening the fiber. A combined scour-bleach bath runs on two actives: caustic soda (sodium hydroxide, CAS 1310-73-2), the alkali that saponifies waxes, and hydrogen peroxide (CAS 7722-84-1), the bleaching oxidant. Run both in one bath where line time is tight; split them when fiber-damage control matters more than throughput.

Alkaline hydrogen peroxide decomposes too fast if trace iron, copper, or manganese are present, and uncontrolled decomposition pits the fiber. Two tools manage this. Chelants — EDTA (CAS 60-00-4) and the stronger DTPA (CAS 67-43-6) — sequester the trace metals; silicate stabilizers such as sodium metasilicate (CAS 6834-92-0) buffer the bath and slow peroxide release. The trade-off is real: more peroxide whitens faster but raises the risk of tendering, so stabilizer dose, not oxidant dose, is the control lever.

Soda ash (sodium carbonate, CAS 497-19-8) sets the milder alkalinity used to buffer scour and reactive-dye baths, where full-strength caustic would be too harsh. For mercerizing-grade swelling you still need concentrated caustic soda; for routine scouring, build the bath from soda ash plus a wetting agent and reserve caustic for wax-heavy goods. Sequence the chelant ahead of the peroxide so metals are tied up before the oxidant is charged.

• Alkaline scouring of cotton greige goods to remove waxes, pectins, and oils
• Hydrogen peroxide bleaching of cellulosics for uniform whiteness before dyeing
• Combined scour-bleach (single-bath) preparation for continuous ranges
• Peroxide bath stabilization and metal-ion control to prevent fiber tendering
• Alkali buffering of reactive-dye and pretreatment baths with soda ash

• Sodium hydroxide (caustic soda) — PubChem
• Hydrogen peroxide — PubChem
• EDTA — PubChem
• DTPA — PubChem
• Sodium carbonate (soda ash) — PubChem
• Sodium metasilicate — PubChem