Send the pigment class. Phthalocyanine, carbon black, and TiO2 are different surfaces. One “paint dispersant” sentence is not a grind formula.
Different surfaces
Titanium dioxide is often treated and relatively easy to wet compared with a crude phthalocyanine or a high-surface-area carbon. A dispersant ladder run only on white will under-disperse the color and then look like a tint problem in the store.
Esteem’s pigment-dispersion range and the ethoxylates marked for phthalocyanine are the coatings door. Naphthalene sulfonate chemistry, covered in the dispersing-agents article, is the other door for some industrial grinds. Say which surface you have.
Let-down shock
A millbase can be fine on the gauge and flocculate when it meets a salty latex or a cationic additive. That is acceptance, not grind. Report it separately so the sample is a wetter or a co-dispersant rather than a higher primary dose that only raises viscosity.
Foam in the mill is a defoamer question. Do not hide it inside the dispersant request or the grind will be judged on air.
| Pigment | Typical need | Poor test |
|---|---|---|
| TiO2 | Wetting at moderate dose | Color strength of a phthalo |
| Phthalocyanine | Stronger dispersion, listed ethoxylates | White-base ladder only |
| Carbon black | High surface area, viscosity | Fineness at one hour |
| Iron oxide | Stability more than strength | A carbon-black dose |
Wetting is not dispersion
A pigment powder is an agglomerate with air in the pores. A wetting agent lowers the contact angle so resin solution or water enters those pores and the agglomerate falls apart under shear. If the primary particles are not then stabilised, they flocculate as soon as the shear stops. Gloss falls and colour strength drops even though the grind looked fine.
Inorganic titanium dioxide accepts anionic polyacrylates, phosphate esters, and some alkoxylates on its oxide coating. Phthalocyanine and carbon black prefer other anchoring groups and often a more hydrophobic dispersant. One “universal” wetter is a compromise that is rarely optimal for both in the same mill base.
Waterborne and solventborne surfaces
In water, charge and EO chains stabilise the particle. In solvent, a dispersant needs an anchor on the pigment and a soluble tail in the resin. Phosphate esters are common anchors on inorganic surfaces in both systems. Fatty-alcohol ethoxylates wet organic and inorganic surfaces but may be too weak as the only stabiliser once the mill base is let down.
The resin itself competes for the surface. A dispersant that worked in a mill base without resin can be displaced when the let-down resin is added. Test colour acceptance after let-down, not only Hegman grind in the mill base.
How overdosing shows up
Too much dispersant stays in the water or solvent phase. It can stabilise foam, cut water resistance, and create a viscosity drop. Too little dispersant shows up as flocculation on drying, rub-up colour change, and flooding of one pigment over another in a mixed tint.
Specify the pigment, whether it is organic or a coated titanium dioxide, the resin, and the grind solids. Ask for a ladder of dispersant on that pigment. A single recommended percentage copied from another pigment is how chalking and colour drift get designed in.
How to Specify with Esteem
- Name the pigment: TiO2 grade, phthalo, carbon, or iron oxide.
- State mill type and let-down resin.
- Record gloss, color strength, and viscosity stability, not grind fineness only.
- Keep the latex emulsifier out of the first dispersant ladder.
- Check shock when the millbase hits an anionic latex.
Start at pigment dispersion for paint and coating. The table already separates textile-printing and phthalocyanine uses on some ethoxylates.