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Chill filtration in whisky: the NCF debate

What chill filtration removes, why non-chill-filtered whisky can turn hazy with ice or water, what the Scotch rules allow, and which distilleries skip it.

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Chill filtration removes the material that can make whisky turn hazy when it gets cold. A bottle labelled “non-chill filtered” (or “NCF”) has skipped that step, but it has still been filtered: all Scotch is filtered before bottling to remove particles of wood. If you add ice or cold water to an NCF whisky and it clouds, nothing has gone wrong.

What actually is chill filtration?

The UK government’s Scotch Whisky technical file sets out the process. All Scotch is filtered before bottling to remove wood particles from the cask. It is also common, but not universal, for Scotch to be chill filtered: the whisky is filtered at a particular temperature to remove what the industry calls haze floc. At low temperatures certain long-chain esters in whisky can come out of solution and form a haze or sediment in the bottle; removing them keeps the whisky clear when the temperature changes.

The exact temperatures, filter media and pressures vary by producer and aren’t usually published.

Why do distilleries do it?

Appearance. The technical file says most consumers expect Scotch to be clear and bright, which is why many Scotch whiskies are chill filtered. It also notes that a haze can appear on storage below about 0°C, and in some Scotch whiskies after mixing with water or ice.

The law limits how far this can go. The filtration must be used only to prevent haze floc and go no further, and it must not be used to remove colour, flavour or aroma, which the definition of Scotch Whisky in the Scotch Whisky Regulations 2009 prohibits.

Strength and haze: is there a 46% rule?

Not in law. Many non-chill filtered whiskies are bottled at 46% ABV or higher, and the idea that higher strength keeps haze-forming compounds in solution is widely repeated, but the sources behind this guide don’t set any strength threshold, and the technical file notes that some Scotch can turn hazy with water or ice whatever its label strength. Scotch can’t be bottled below 40% ABV. Read the label: whether a whisky is chill filtered is a statement the producer makes, not something you can infer from its ABV.

Non-chill filtered whiskies are often bottled at natural colour too, but the two are separate choices, so check for each statement on the label. Our guide to spirit caramel (E150a) covers the colour side.

The sensory debate: flavour vs mouthfeel

Many drinkers and producers who skip chill filtration say it affects texture and finish. The evidence for a difference people can taste is thin. In a blind study published by the German retailer whisky.com, 111 participants tasted chill-filtered and non-chill-filtered versions of the same single malts and identified the chill-filtered sample correctly 45% of the time, about what guessing would give. One study doesn’t settle the question, and a preference for non-chill filtration can also be about wanting whisky handled as little as possible.

Flocculation Chemistry and Turbidity

Turbidity (haze) in whisky is a reversible physical phenomenon governed by the solubility limits of hydrophobic lipids in ethanol-water solutions:

The 46% ABV Stability Threshold

In practice, distilleries choosing not to chill-filter adopt 46.0% or 46.3% ABV as a natural stability buffer. While FAEEs will still precipitate if whisky is served with large amounts of ice, spirits kept above 46% ABV rarely cloud at ambient room temperatures in domestic storage, avoiding consumer returns while retaining the long-chain esters that provide viscosity and mouth-coating texture on the palate.

Non-chill filtered whiskies to compare

Each of these states non-chill filtration on the producer’s own site:

The cloud test

You can see the effect yourself. The Scotch Whisky Association says non-chill filtered Scotch will go cloudy if ice is added to it. A chill-filtered whisky is meant to stay clear. Either way, the haze is cosmetic: it is a change in appearance, not a fault in the whisky.

Sources and review

Questions

Which Scotch distilleries say they don't chill-filter?
Several state it on their own sites. Springbank says its whisky is never chill filtered. Deanston says all its whisky is non-chill filtered, and Kilchoman says the same of all its bottlings. Bunnahabhain says it of its core range, Bruichladdich of its unpeated Bruichladdich range, and Arran and Tobermory state it as house practice. A policy can change, so check each release.
Is chill filtration allowed in Scotch whisky?
Yes, within strict legal limits. Chill filtration may be used only to prevent haze floc (long-chain esters and fatty acids that precipitate at low temperatures). It cannot be used to remove colour, flavour, or aroma from the spirit.
What does chill filtering do to whisky?
It removes the compounds that can make whisky cloudy when chilled or diluted. Certain long-chain esters and fatty acids precipitate at low temperatures to form a haze or sediment, so whisky is chilled and passed through fine filters to ensure it stays clear in the bottle.
Is non-chill filtered whisky better?
There’s no settled answer. Many drinkers prefer non-chill filtered whisky, but the Scotch rules say filtration must not be used to remove flavour, and in a blind study published by the German retailer whisky.com, 111 participants identified the chill-filtered sample correctly only 45% of the time. Choose by the label statement if it matters to you.

About the author

John Fegan

· Editor

Hailing from the land of haggis and deep-fried Mars bars, John was always going to find his way to whisky. He has run Uisge Beatha since 2015 and Whiskipedia.com since 2020.