Pigment and Filler Dispersion in Paints

Dispersion (in chemistry) is the process of creating a stable suspension of pigments and fillers in a liquid. It consists of three steps:

• wetting,
• separation, and
• stabilization.

Naturally, pigments and fillers tend to agglomerate and create 'lumps'. It is detrimental to the paint properties. Dispersion is the only way to get optimal effects out of solid particles.
 

To an extent, suppliers sell 'pigment dispersions', which corresponds to pre-dispersed pigment solutions.

Here is a selection of resources to learn about the dispersion process:
 

Pigment dispersion is the costliest step in the production of coatings and inks. First, pigments and other solid additives can be quite expensive on their own. You do not want to load them in excess in your formulation. Excess loading can lead to more troubles than solutions. The only way to get the most out of your solid particles is to disperse them well.

The dispersion process is quite energy-intensive and lengthy. To minimize these drawbacks, you should select adequate dispersants and equipment. 

 

To ensure you have reached a good dispersion of your solid particles, you would generally check:

• The fineness of grind
• Color strength
• Viscosity
• Dispersion stability over time
• Time to achieve your specific targets for the above properties

Beyond the process itself, the quality of the dispersion affects many coating properties:

• Opacity of the system
• Glossy finishes
• Storage stability

There are many ways a dispersion can go wrong. Here are the most frequent problems and how to overcome them: