First, the cleaning before soaping after dyeing must be strengthened. 

Such as appropriately increasing the washing temperature, appropriately extending the washing time, appropriately increasing the number of water changes or appropriately speeding up the flow of water, etc. Improving the cleaning effect before soaping is the basis for improving the soaping effect.

Second, choose a soaping agent with good washing ability, dispersing ability, emulsifying ability, and dirt-carrying ability.

which is very important for improving the soaping effect.

Third, add 1-2 grams per liter of chelating dispersant to the soaping liquid. 

Chelating dispersant has good dispersing and suspending functions for impurities in soaping liquid, prevents equipment and fabrics from being stained, and has good complexing ability, which can chelate calcium and magnesium ions in water to prevent the formation of calcium Lake of magnesium dyes, reducing soaping effect. Sodium hexametaphosphate should not be used in soaping, but can only be used for dyeing, because its ability to chelate metal ions will decrease significantly under high temperature conditions.

Fourth, soaping must be carried out at pH=6-7 under neutral conditions.

This is because the bond between the reactive dye and the fiber has a limited ability to resist acid and alkali hydrolysis. Under high temperature conditions with strong acidity and alkalinity, the bonded dye may be hydrolyzed and broken to become The new floating color dye not only affects the color depth, but also affects the soaping effect.

In actual production, in order to increase production and reduce energy consumption, after dyeing, some dyes are soaped with unclean water, forming "alkaline soaping"; some are directly neutralized with acid, and often form "acid soaping".

Production practice has proved that no matter whether it is a s-triazine dye (K type, X type), or a vinyl sulfone dye (KN type), or a mixed dual-reactive dye (M type, ME type, A type, B type, etc.), Their dye-fiber bonds were most stable at pH=6-7, and the stability of dye-fiber bonds decreased when the pH value increased or decreased. "Alkaline soaping" is easy to hydrolyze and break the vinylsulfone dye-fiber bond, and "acid soaping" is easy to hydrolyze and break the s-triazine dye-fiber bond. Reactive dyes with high acid and alkali stability are relatively better than dyes with a single reactive group.