Overview of colour dispersions in cosmetics

 The colouring material in a particular formulation depends on the desired colour effect. For example, in the case of a shimmering eye shadow, a onehundred micron interference flake type material could be used, whereas in the case of a foundation, pigments less than one micron are used for a skin tone match. To formulate with pigments in powdered form requires proper handling and processing prior to and during formulation. Using colour dispersions alleviates these types of intermediate steps and offers benefits of colour development with consistency of batches. Dispersions of metal oxides and organic pigments in multiple carriers are typically available. Only homogenisation may be required to have a successful, final product based on a colour dispersion.

Dispersion overview

A material defined as a dispersion is characterised as particles that are dispersed in a continuous phase of a different composition. Dispersions are structured to include a pigment, a vehicle, and a dispersant. First is the vehicle. This is essentially the liquid that the particulate medium is dispersed in. The next element is the dispersant. The dispersant functions to assist in wetting out the pigment, prevent settling, and stabilise the pigments by ensuring pigment separation in the dispersion. Wetting out the pigment is important to increase the concentration of the pigment in the chosen vehicle. Often the pigment includes a surface treatment. This is the solid being dispersed. The treatment aids in helping to wet out the pigment, achieve a uniform dispersion, and allows for a higher solid content. Additionally, treatments can help to neutralise a charge on the outer surface of a pigment and to help reduce the aggregates to make smaller size pigments. Treatments reduce the friction and adsorption on pigments so more concentrated dispersions can be achieved.