Levelling agents in reactive dyeing: what they actually do
Levelling agents don't fix a bad recipe, but they buy you the time and control a good one needs to land evenly.
A levelling agent works by controlling the rate at which dye migrates onto the fibre, giving the dye bath time to distribute evenly before fixation. This matters most on long fabric runs and in machines with less-than-perfect liquor circulation.
The trade-off is exhaustion speed: too much retardation and you lose colour yield, too little and you get tailing or side-to-centre variation. The right dosage depends on your dye class, liquor ratio and machine type.
If you're seeing consistent shade variation across a batch rather than random spotting, that's usually a levelling issue rather than a fixing issue.
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