2. Formulation

2.1 Paste

Figure 11 summarizes the various phases of a paste formulation. Generally speaking, a toothpaste in paste form is a suspension, i.e. a dispersion of fine solid particles in a liquid in which they are insoluble. This mixture is therefore a heterogeneous system consisting of a continuous outer liquid phase, called the dispersing phase, and an inner phase of fine solid particles, called the dispersed phase. The addition of a stabilizer (e.g. a gelling agent) stabilizes the medium over time