Classification is primarily by particle charge and setting behavior. Cationic emulsions have positively charged droplets and are often preferred for many aggregates due to adhesion. Anionic emulsions have negatively charged droplets and can be preferred with certain alkaline aggregates or applications. Non ionic emulsions rely on steric stabilization rather than charge and are less common for road works. Standards also classify by setting rate such as rapid, medium, or slow and by residue and viscosity limits.