This is the process when an O/W emulsion changes to a W/O emulsion or vice versa. As already mentioned, soaps of monovalent metals produce O/W emulsions, whereas soaps of divalent metals produce W/O emulsions. The emulsion type is determined by the solubility of the emulsifying agent. If it is more soluble in water than in…
Creaming is the separation of an emulsion into two regions, one of which is richer in the disperse phase than the other. It is not a serious instability problem as a uniform dispersion can be reobtained by shaking the emulsion. However, there may be coalescence of droplets as they are present close to each other.…
The globules of the disperse phase coalesce together and form a separate layer. Redispersion cannot be achieved by shaking and the preparation is no longer an emulsion. Cracking may be caused by the following:
Learning Objective An emulsion is a thermodynamically unstable preparation. So, care has to be taken to maintain the physical and chemical stability of the preparation throughout its shelf life. There should be no appreciable change in the mean particle size or the size distribution of the droplets of the dispersed phase. The droplets of the…
The amount of emulsifying agent used is dependent on the amount and type of oil to be emulsified. Oils can be divided into three categories: fixed oils, mineral oils and volatile oils. (Note: Gum is the emulsifying agent or emulgent.) These proportions are important when making the primary emulsion to prevent the breaking down of emulsion…
Learning Objective The preparation of an emulsion involves two stages:
The formulation of emulsions involves the following: