Reactive Dye Auxiliaries

Reactive dye auxiliaries are the non-dye chemicals that drive cellulosic reactive dyeing: electrolytes that push dye onto the fiber, alkalis that fix it, and process aids that keep the bath clean and even. They carry no color themselves. Get the electrolyte and alkali dosing right and shade depth, levelness, and wash fastness follow.

Electrolyte forces dye exhaustion onto the fiber. Two salts dominate: sodium sulfate (Glauber's salt) and sodium chloride (common salt). Common salt is cheaper per tonne, but its chloride attacks stainless-steel dyeing machinery over time; sodium sulfate costs more and is gentler on equipment. Choose by total cost, counting machine corrosion, not the salt invoice alone. Typical dosing runs tens of grams per liter, scaled to shade depth.

Alkali triggers the dye-fiber bond. Soda ash (sodium carbonate) is the standard fixation alkali; sodium bicarbonate gives slower, more controlled fixation for difficult shades. Hard-water metal ions cause shade variation and dye aggregation, so a chelant such as EDTA sequesters calcium, magnesium, and iron in the bath. Urea aids dye solubility and fiber swelling, and acetic acid neutralizes the bath before unloading. Soften the water first; it is the cheapest fix for off-shade lots.

• Exhaust and pad-batch reactive dyeing of cotton, viscose, and other cellulosics
• Electrolyte dosing for controlled dye exhaustion and shade depth
• Alkali fixation programs (soda ash / bicarbonate) for level, wash-fast shades
• Bath sequestration of hardness metals to prevent shade variation
• Post-dye neutralization and pH control before soaping and rinse

• Sodium sulfate — PubChem
• Sodium chloride — PubChem
• Sodium carbonate (soda ash) — PubChem
• Sodium bicarbonate — PubChem
• EDTA — PubChem
• Urea — PubChem
• Acetic acid — PubChem