1.Increase the dyeing temperature
By increasing the dyeing temperature, the structure of the fiber can be expanded, the movement function of the dye molecules can be accelerated, and the chances of the dyes spreading to the fiber can be increased. So when dyeing dark color fabrics, we always try to increase the dyeing temperature to increase the dye-uptake. However, unilaterally increasing the dyeing temperature may influence the strength of dyed fabrics and may also cause high temperature discoloration or hydrolysis of some dyes, as well as dyeing defects on chemical fibers. But the dye-uptake of some dyes decreased with the increase of dyeing temperature, which is desorption phenomenon. Therefore, it is not scientific to increase the dyeing temperature to increase the dye-uptake.
2.Increase the dosage of dyes
In order to dye dark color fabrics, some factories mostly increase the dosage of dyes to achieve dark color. Due to the huge amount of dyes, it will be more difficult to treatment dyeing wastewater. And sometimes, although the dark color is achieved, the color fastness is very poor. So in the market, there are some dark color fabrics easily fade after washing.
3.Add electrolyte to promote dyeing
For reactive dyes and direct dyes, adding electrolyte, as NaCl and Na2SO4, etc. during dyeing will promote the dyeing. For acid dyes, adding HAC and H2SO4, etc. will promote the dyeing. These methods will improve the dyeing rate and dye-uptake on fabrics to a certain extent. And for large amount of dyes in dark color dyeing, there is more usually adding promoting agent.
However, adding too much electrolyte will not only decrease the brightness of fabrics, but will cause coagulation of dyes, which will leads to quality problem.
Post time: Jun-14-2024