Chill filtering

Chill filtering prevents the whisky from becoming hazy when in the bottle, when served, when chilled, or when water or ice is added, as well as precluding sedimentation from occurring in the bottles. It works by reducing the temperature sufficiently so that some fatty acids, proteins and esters (created during the distillation process) precipitate out and are caught on the filter. Single malt whiskeys are usually chilled down to 0°C, while the temperature for blended whiskey tends to be lower because they have lower levels of fatty acid.

Factors affecting the chill filtering process include the temperature, number of filters used, and speed at which the whiskey is passed through the filters. The slower the process and the more filters used, the more impurities will be collected, but at increasing cost.

Because this process is believed to sometimes affect the taste of the whisky, for example, by removing peat particles that contribute to the smokiness of the flavor, some distilleries pride themselves on not using this process. Non-chill-filtered whisky is often advertised as being more "natural", "authentic", or "old-fashioned". For example, the Aberlour Distillery's distinctively flavored A'bunadh whisky, Laphroaig's Quarter Cask bottles, and all of Springbank distillery's whiskies are not chill-filtered and are advertised as such.