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why need add salt in direct dyeing?

From: FAQ | Date:2020/2/28 | Hit:

Adding salt to the dyeing solution can increase the percentage of dyeing. A very important reason why salt has a dye-dyeing effect is to reduce the charge effect during fiber dyeing. Cellulose fibers are in neutral or weakly alkaline dye baths. There is a surface potential, which generates a charge repulsion with the direct dye anion. After the electrolyte is added, a large amount of positively charged sodium ions are generated in the dye solution, and the charge anion is kept neutral with the dye anion, thereby eliminating obstacles in the dyeing process and making the dye molecules and fibers. The surface is in close contact, which reduces the concentration difference between the dyeing liquid and the fiber interface, thereby increasing the dyeing percentage of the dye. However, the dyeing process of the direct dye can be roughly divided into three stages: adsorption, diffusion and fixation. In the adsorption stage, it should not be too fast. Coloring, if the electrolyte is added during the adsorption phase, it is possible to cause the dye to aggregate and cause unevenness, and the electrolyte is added in the middle to avoid excessive coloring and increase the percentage of dyeing.

EMPEROR company strongly recommend for Direct dye as bellow:

Direct Red 13, Direct Red 23, Direct Red 28, Direct Red 31

Direct Yellow 11, Direct Yellow 12, Direct Yellow 50, Direct Yellow 96

Direct Orange 26

Direct Green 1, Direct Green 6

Direct Blue 15, Direct Blue 71, Direct Blue 86, Direct Blue 106, Direct Blue 151, Direct Blue 199

Direct Black 19, Direct Black 22, Direct Black 38, Direct Black 56, Direct Black 168

Direct Brown 1, Direct Brown 2, Direct Brown 95, Direct Brown 210


If you are are interested us, pls feel free to contact us. our TEL is 0086-15958136613 Ms Gloria XU

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