Levelling agents

in every dye house ,levelness of the dyeing is a major criteria , since unlevelled    goods are usually not saleable ,causing loss to the manufacturer.

Leveling
Migration of applied dyes in a uniform manner throughout the dyed goods is called leveling and it may be a property of the dye or it may require some chemical assistance (of leveling agents which are dye bath additives
 to promote level dyeing)
Levelling agents are invariably surfactants ;they may be anionic ,cationic,non ionic or amphoteric in nature .some times combinations of these are also used ,There are two fundamental mechanisms that can contribute to a level dyeing:

1.Control of rate of exhaustion of the dye so that it is taken evenly and slowly.

2.Migration of the dye after initial uneven sorption on the fiber.

In complex formation the principle of leveling is usually the same ,irrespective of whether non ionic or ionic agents are used , although the mode of complexing is different.

The attractive forces between leveling agent and dye creates a counter balancing mechanism against dye fiber attractive forces,restraining the uptake of dye by the fiber.

As the temperature of the dyebath increases , the complex gradually breaks down ,progressively releasing dye for more gradual sorption by the fiber.

further reading :-Role of leveling agents in textile wet processing
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