Material Inefficiency
Chemical reactions between reactive dyestuffs and cellulose fibers result in a portion of the colorant failing to bond and subsequently washing away. Calculating the reactive dyeing loss involves measuring the difference between the dye applied to the bath and the dye permanently fixed to the fabric. Measurements of this type account for hydrolyzed dye molecules that lose their ability to form covalent bonds with the cotton.
Environmental Impact
Unfixed dyes end up in the wastewater stream, necessitating extensive treatment before the water can be discharged. High reactive dyeing loss increases the chemical oxygen demand in the effluent and raises the cost of water purification. Efficient dyeing systems aim to minimize this waste through better temperature control.
Cost Factor
Dyeing recipes must include an excess of chemicals to compensate for the portion that will not fix. When reactive dyeing loss is high, the cost per meter of fabric increases.
Fixation Method
Adjusting the pH and salt concentration in the dye bath helps to maximize the bond formation. A reduction in reactive dyeing loss is often achieved by using bi-functional or poly-functional dyes that offer more sites for attachment. Precise control of the washing-off process ensures that any remaining loose dye is removed without affecting the final shade.
