Redistilling

Redistilling is the process of distilling a liquid that has already undergone a first distillation, with the aim of increasing purity, removing impurities, or altering the product's composition or flavor. It is commonly used in the production of spirits to refine quality, in chemical processing to purify solvents or fractions, and in the extraction of essential oils or aromas where a second pass can improve separation of components with similar volatilities.

In practice, redistillation relies on differences in boiling points to separate components. The distillate from the first run is fed again into a still or column, where vapors condense into a purer or differently composed product. Depending on design, it may involve rectification via a fractionating column to achieve finer separations, or a single re-pass to adjust characteristics. The term rectification is often used to describe this refining step in the spirits industry.

In spirits production, redistillation is used to remove off-flavors and congeners, concentrate ethanol, and attain a desired flavor profile; in more general industrial uses, repeated distillations can increase purity of solvents, recover valuable fractions, or prepare feedstocks for further processing.

Regulatory considerations: Distillation of alcohol for beverage use is heavily regulated in many countries and generally requires licenses, compliance with safety and labeling standards, and adherence to maximum alcohol contents. Redistillation of alcohol without authorization can be illegal. Safety: Distillation involves flammable vapors and heat; improper handling can lead to fires, explosions, or toxic methanol production; therefore, redistillation should only be conducted in appropriate, legal contexts with proper equipment and training.

See also: rectification, fractional distillation.