The question: I just bought a bottle of whisky and the label says “non-chill filtered.” What does that mean?
The answer: Most conspicuously, it means your whisky may turn hazy if served on 'the' rocks. But that’s not a bad thing. Chill filtering is a step most distillers take to remove chemical compounds such as esters, proteins and acids produced during fermentation and maturation. The spirit is cooled to roughly 0 C, which causes the compounds to precipitate out of the solution. This makes it possible to trap them in a fine filter. Mainly, it’s a cosmetic procedure. Whisky bottled at a typical alcohol content of less than 46 per cent will become cloudy if subsequently chilled, either during transport or in the presence of ice.