A dispersion is a system in which particles are dispersed in a continuous phase of a different composition. A dispersion can consist of 4 variables: pigment, surface coating, dispersant, and vehicle. For the pigment, we will focus on ZnO and TiO2 in this post. Attention must be made to the primary particle size of the ZnO and TiO2. You do not want it to be too large. The surface coating reduces aggregation and reduces oil absorption so that the dispersion flows and is not chunky. The dispersant improves wetting and stabilizes the suspended particle. The vehicle provides a medium and wets the particulate.
Dispersions are great to use because they are so convenient. It is so much easier to just put the dispersion into your formula instead of making grinds. The particle size in the dispersion is made to the ideal size so you will get better results on your SPF and UVA testing. In addition, there will be better transparency in the finished sunscreen formula because of the small particle size in the dispersion. Dispersions help cut labor and enhance skin feel. I love to use dispersions!
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