A functional fluid useful as an emulsion in a cleaning product or a personal care product is the esterification reaction product of a) a triglyceride or a fatty acid or a methyl ester of a fatty acid, and b) an alcohol which comprises bl) a polyglycerol having at least 3 glycerol units (preferably polyglycerol-4), and b2) glycerol and / or diglycerol. The functional fluid is effective as a stabiliser and as an emulsifier for o/w and w/o emulsions. When a triglyceride is used as a reactant, glycerol and fatty acids are generated in situ by an interesterification reaction. Preferred functional fluids provide the significant benefit that they may be mixed into an oil phase and in a water phase before such phases are mixed together, and that such processing may be carried out at ambient temperature.
