Particle properties such as hydrophobicity, shape, and size, as well as the electrolyte concentration of the continuous phase and the volume ratio of the two phases can have an effect on the stability of the emulsion. The particle’s contact angle to the surface of the droplet is a characteristic of the hydrophobicity of the particle. If the contact angle of the particle to the interface is low, the particle will be mostly wetted by the droplet and therefore will not be likely to prevent coalescence of the droplets. Particles that are partially hydrophobic are better stabilizers because they are partially wettable by both liquids and therefore bind better to the surface of the droplets. The optimal contact angle for a stable emulsion is achieved when the particle is equally wetted by the two phases (i.e. 90° contact angle). The stabilization energy is given by