In the dyeing process of fiber yarn, line or fabric , in order to promote uniform dyeing without color bars, spots and other added substances, leveling agents are here to use. Most of the leveling agents are water-soluble surfactants, which are divided into two types according to the effect of leveling agent on the diffusion and aggregation of dyes: one is fibrous leveling agent, which has little effect on the concentration of dyes. http://www.ezalchemical.com/dyeing-auxiliary/leveling-agent/