Dispersing & Levelling Agents
A dispersing agent keeps the dye suspended in the bath as fine particles; a levelling agent evens out how fast the dye moves onto the fibre. Both aim at one thing: the same colour everywhere on the cloth. Four families, 10 products.
Are a dispersing agent and a levelling agent the same job?
No, but they aim at the same result: even colour. A dispersing agent keeps a water-insoluble dye (a disperse dye) suspended as very fine particles. Let the particles agglomerate and they settle out of the bath, spot the fabric and block the filters.
A levelling agent slows how fast the dye moves onto the fibre. If the dye strikes too quickly, the first area it reaches comes out dark and the rest light; opened out, the cloth shows unlevelness. A levelling agent interacts temporarily with the dye or with the fibre, which evens out that rate and gives the dye time to migrate.
Where does unlevelness come from?
The source is usually the process rather than the dye:
- Heating gradient. Most of the dye exhausts within a narrow temperature band. Pass through that band too quickly and the dye has no time to distribute.
- Liquor circulation. Overloading, pump speed and foam all disturb circulation, and wherever the liquor does not reach stays light.
- Fibre variation. Yarn from a different lot takes up dye differently. Maturity differences in cotton, and draw differences in polyamide, show up as streaks.
- Uneven pre-treatment. Cloth with uneven hydrophilicity never dyes evenly.
A levelling agent compensates for the first and third items. The second and fourth belong to the machine and to pre-treatment, and no chemical closes them.
Which family goes where?
|
Family |
Fibre / process |
Function |
|---|---|---|
|
Dispersing agents |
Polyester, disperse dyeing |
Keeps dye particles fine and suspended, reduces oligomer build-up |
|
Levelling agents |
Cotton and blends |
Evens the strike rate and reduces unlevelness |
|
Speciality chemicals |
Polyester |
Cationic structure improving dye penetration into the fibre |
|
Denim washing dispersants |
Denim and garment |
Holds stripped indigo in the liquor and reduces back-staining |
Denim is a heading of its own. In stone washing and enzyme washing, the indigo lifted off the surface is left free in the bath; if it redeposits on pocket lining or sewing thread, the garment is scrapped. Holding that indigo in suspension is what a denim dispersant is for.
Does a levelling agent bind to the dye or to the fibre?
Both routes are used. Agents with a high affinity for the dye form a temporary complex with the dye molecule; the dye can only move onto the fibre as that complex breaks up, so uptake slows. Agents with a high affinity for the fibre block the active sites on the fibre temporarily and compete with the dye for them.
The difference shows in use. The dye-binding type costs more colour yield; the fibre-binding type makes it easier to hit the target shade on darks, but it can shift the shade balance on blends. Which type is in the recipe has to be known when the recipe is built.
Why are oligomers a problem in HT dyeing?
Around 130 °C, polyester releases its own low-molecular-weight oligomers to the surface. On cooling these crystallise as a white powder on the cloth and on the machine, spoiling the handle and spotting the next batch. Some dispersant structures are formulated to hold that oligomer in suspension as well, so it leaves the system with the cooling drain.
Per-product dosage and working conditions are given on each product page: pending from the client.
Product families
Products in this category
Denim Washing Dispersants3 products
- DK DBS 1
Denim washing dispersant that holds stripped indigo in suspension and keeps pocket bags and seams from blueing.
- DK DBS 2 CONC
Concentrated denim washing dispersant that controls back-staining at low dosage on deep indigo washes.
- DK DBS 3
Denim washing dispersant, the third product in the range, set up to share a bath with an enzyme wash.
Dispersing Agents2 products
- DK EG 111
Dispersing agent for polyester dyeing that keeps disperse dye particles apart through the HT cycle.
- DK EG 111 PLUS
Speciality polyester dispersing agent that holds dispersion stability high on dark shades and package dyeing.
Levelling Agents4 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.
Speciality Chemicals1 product
- DK SYNTHEDIF
Penetrating agent for cationic-dyeable polyester that stops basic dye piling up at the surface of the fibre.
Common questions
Will more levelling agent cure unlevelness?
Only up to a point. Because it slows exhaustion, an overdose lowers colour yield and puts dark shades off target. If unlevelness persists, slowing the heating ramp and reducing the machine load act more directly.
Is a dispersant needed in every disperse dyeing?
Commercial disperse dyes already carry dispersant, but that amount may not hold up at high temperature over a long cycle. Adding dispersant to the bath is standard practice on dark shades, in hard water and on long HT programmes.
How does a denim dispersant differ from a washing-off agent?
Different target. A washing-off agent is formulated around hydrolysed reactive dye; a denim dispersant works on water-insoluble indigo particles and also has to disperse solid residue such as pumice dust.
Not finding what you need?
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.