Unfortunately there are a limited number of suitable emulsifiers and those available are often restricted in application. Obviously the emulsifier has to be either a liquid or readily soluble in either the aqueous or oil phase of the composition. The oil phase itself cannot contain any waxes or wax-like materials, which precludes glyceryl stearate and cetearyl alcohol, those two favourite ingredients of the emulsion formulator. Because waxes cannot be used to thicken products a rheology modifier is necessary and must be selected with care.