The process of Fractional Distillation is a technique used to isolate or purify various components present in essential oils. Fractional distillation separates the volatile oil in different fractions or portions at various boiling points. The essential oil is evaporated in the fractionating column and its vapours are allowed to condense at different temperatures. A process of rectification is used to obtain the product in the purest form possible.

Fractional Distillation is typically performed in large, vertical cylindrical columns known as ‘distillation or fractionation towers’ or ‘distillation columns’. The distillation towers have liquid outlets at intervals up the column, which allow withdrawal of different fractions or products having different boiling points or boiling ranges. By increasing the temperature of the product inside the columns, the different volatile components are separated. The ‘lightest’ products (those with the lowest boiling point) exit from the top of the columns and the ‘heaviest’ products (those with the highest boiling point) exit from the bottom of the column.