Waxes are esters formed by the combination of fatty acids with high molecular weight alcohols. In most cases, waxes are hard, brittle substances with high melting points. A notable exception is Sperm Oil which is a liquid obtained from the head cavity of the Sperm Whale.

A type of fractionation in which liquid oils are cooled in order to precipitate any solid constituents (stearine) which may then be removed by filtration, the filtrate being known as a winterised oil. These oils are used mainly for culinary purposes where the appearance of solids from the unwinterised oil in cold weather would lead to undesirable cloudiness.