Nylon woven greiges has acrylic and wax etc. added as a sizing agent to the warp. These are a secondary contaminant applied in the process before the weaving. In the pretreatment process, secondary contaminants are removed by continuous treatment.
Acid dyes and premetallized dyes are used in dyeing of nylon which are water-soluble and dyed by ionic bonding. In dyeing process, various dyeing auxilliaries such as levelling agents for level dyeing, soaping agents for washing off unfixed dyes for improving dye fastness, fixing agents for fixing dyes to fibers or fabric are used.