Sodium sulfate is used as a direct dye and other cotton dyeing promoter in the printing and dyeing industry.


When dyeing cotton with direct dyes, sulfide dyes, vat dyes, and printing dyes, sodium sulfate can be used as a dyeing promoter. These dyes are easily soluble in the formulated dye solution, but they are not easy to dye cotton fibers. Due to the difficulty in absorbing the dye completely, there is a lot of residual dye in the foot water. Adding sodium sulfate can reduce the solubility of dyes in water, thereby increasing their coloring power. In this way, the amount of dye used can be reduced while the resulting color deepens.


1. The amount of sodium hydroxide powder depends on the coloring power of the dye used and the required color depth. It should not be added too much or too quickly, otherwise it will cause the dye in the dye solution to precipitate and cause stains on the fabric surface.


2. When cotton fabric is rolled and dyed, sodium sulfate is usually added in batches in the 3rd to 4th layers. As the dye solution is very thick before dyeing, if added quickly, the dye will dye the fibers too quickly and cause unevenness. Therefore, it is advisable to dye for a period of time before adding it.


3. Yuanming powder should be thoroughly deepened with water before use and filtered before being added to the dyeing bath. It is also necessary to stir the dyeing bath while slowly adding it to prevent local dyeing baths from salting out due to contact with a large amount of dye promoting agents.