Levelling Agents
Unlevelness usually comes not from too little dye but from dye reaching different parts of the fabric at different rates. A levelling agent slows the strike and leaves room for dye already on the fibre to redistribute.
Why does unlevelness happen?
The causes do not sit in one place. The common ones are uneven absorbency carried over from pre-treatment, dye added to the bath too quickly, electrolyte dosed all at once, a machine that cannot circulate the fabric evenly, and temperature gradients across the vessel.
A levelling agent touches only part of that list. By slowing the rate of strike it buys time for the dye to reach the whole piece, and it makes it easier for early-struck dye to redistribute. A bleaching fault, or a machine that cannot turn the rope properly, will not be closed with chemistry.
How does a levelling agent work?
Two mechanisms run together.
Retardation. The agent forms a temporary association with the dye, or competes for binding sites on the fibre surface. Either way the rate of strike in the first minutes drops. With a slower strike, every part of the fabric meets the dye under similar conditions.
Migration. This is the redistribution of dye already on the fibre, from darker to lighter areas. In reactive dyeing migration is only possible before fixation begins, which means before the alkali goes in. Once alkali is added the dye bonds covalently and the distribution is locked.
How much does salt and alkali dosing matter?
A great deal. In reactive dyeing, levelness is decided during these two dosing steps.
Add the electrolyte in one shot and the dye rushes onto the first fabric surface it meets, leaving a dark area there. Progressive dosing prevents that. The same holds for alkali: adding it fast starts fixation early and leaves no time for migration.
A levelling agent will not rescue a badly built dosing profile. It adds a margin of safety to a well built one.
When is a combined dispersing and levelling product used?
Carrying both functions in one product simplifies the recipe. Combination products formulated for cotton keep the dye from aggregating in the bath while also regulating the rate of strike. The approach suits blends and baths carrying more than one dye class. The intended use for each product is given on its page: pending from the client.
Product comparison
Comparison
| Product | Description | Suitable fibre | Function | Dosage | Temperature |
|---|---|---|---|---|---|
| DK EG 111 A | Dispersing and levelling agent for cotton | Cotton | awaiting data | awaiting data | awaiting data |
| DK EGP 100 | Levelling agent for cotton | Cotton | awaiting data | awaiting data | awaiting data |
| DK EGP 200 | Levelling agent for cotton | Cotton | awaiting data | awaiting data | awaiting data |
| DK EGP NEW | Speciality levelling agent for cotton | Cotton | awaiting data | awaiting data | awaiting data |
Products
- DK EG 111 A
Dispersing and levelling agent for cotton that slows the strike and holds stripped dye in suspension.
- DK EGP 100
Levelling agent for cotton that keeps dye distribution even through the minutes when salt and alkali are dosed.
- DK EGP 200
Levelling agent for cotton that opens room for migration, so an unlevelness that has started can still even out.
- DK EGP NEW
Speciality levelling agent for cotton, holding levelling behaviour steady in dark shades and high-salt recipes.
Common questions
Does a levelling agent reduce colour yield?
At high dosage it can. An agent that competes with the dye slows the strike and may also pull total exhaustion down a little. Check depth of shade whenever the dosage is raised.
Can unlevelness be corrected after the event?
In reactive dyeing migration stops once fixation is complete, so chemical correction is limited. The usual route is to overdye darker or to strip and redye, and both cost money.
When is the levelling agent added?
Before the dye, while the bath is being set. Adding it with the dye, or after it, leaves the retarding function largely without effect.
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We develop custom formulations. Tell us your process, machine type and the result you are after, and the lab will set up a trial and send a sample.