No Soap Reactive Dyeing

Question: Is soaping necessary after Reactive dyeing of cellulosic materials? Or Why soaping is essential after dyeing?

Answer: Omitting the use of detergents in after washing of cotton dyed with reactive dyes :

Description: Both international literature and practical experience in textile mills show that detergents do not improve removal of hydrolysed reactive dyestuffs from the fabric.On the contrary, high temperatures do have an affect on rinsing effectiveness. Tests carried out with rinsing at 90 - 95 °C have shown that rinsing is more effective and faster at high temperatures. About 30 % more unfixed hydrolysed reactive dyestuff is rinsed out after 10 minutes of rinsing at 95 °C than at 75 °C.Many dye houses already carry out hot rinsing and omit the use of detergents in rinsing after reactive dyeing. The product quality is not negatively affected. On the contrary, most often the fastness of the goods are better after the hot rinsing than after the traditional rinsing with detergents, complexing agents and neutralisation in the first rinse.Energy should be recovered when using large volumes of hot process water. Energy reclamation can be done either by heat exchange between the hot outgoing process water and the cold incoming clean water or by reclamation of the hot water and re-use of both energy and water.

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