Dispersion – Cosmetic Uses in Pigmented and Suspension-Based Products

What Is a Dispersion?

A dispersion is a system in which one phase is distributed as particles throughout another continuous phase. In cosmetics, the dispersed material is often a solid powder or pigment, while the continuous phase may be water, oil or another liquid.

Unlike a solution, the dispersed material is not molecularly dissolved in the continuous phase.

Cosmetic Uses of Dispersions

Dispersions are widely used in cosmetic formulations containing insoluble or poorly soluble materials, including:

• Pigments in foundations and colour cosmetics
• Mineral UV filters in sunscreens
• Clay and mineral particles in face masks
• Powders in liquid and cream formulations
• Insoluble active or functional ingredients

Good dispersion is particularly important for pigmented products because uneven particle distribution can result in inconsistent colour, coverage and application.

Dispersion Stability

A stable dispersion requires the particles to remain sufficiently separated and uniformly distributed throughout the formulation. Without adequate stabilisation, particles may aggregate, flocculate, sediment or cream, depending on their density and the continuous phase.

Particle size, surface properties, viscosity, density differences, pH and electrolyte concentration can all influence dispersion stability.

Formulation and Processing

Dispersing agents can be used to improve particle wetting and reduce aggregation. Appropriate mixing, high-shear processing or milling may also be required, particularly for pigments and mineral powders.

The dispersion should be evaluated in the complete formulation because changes in viscosity, surfactant concentration or other ingredients can significantly affect its physical stability.

Stability testing is essential to confirm that the particles remain uniformly distributed throughout the intended shelf life.