One of the more uncommon debates among whisky drinkers is whether you prefer your brand to be “non-chill filtered”. Chill filtration is a somewhat controversial practice among whisky distillers. The outcome is not always advertised on the bottle labels – which is why chill filtering is not a common topic of discussion. But serious whisky enthusiasts definitely have an opinion.

Let’s find the real scoop.

What is chill filtered whisky?

The decision on whether to chill filter arises due to a build-up of chemical compounds during the distillation process of whisky. Besides sediments, a number of proteins, fatty acids and long-chain esters or ether-based diols are present in the whisky that comes out of the barrel.

If the alcohol content is below 46% Alcohol by Volume (ABV) – some say the threshold is slightly lower – these compounds create a cloudiness and haze when the whisky is chilled, as may happen when someone puts ice in their drinks. The haze is not harmful, but the cloudiness may offend the aesthetics of certain drinkers. Some distillers, especially of whisky with ABV lower than 46%, therefore prefer to chill filter their products prior to bottling them.

The chill filtering process

Chill filtration refers to a process whereby the whisky coming fresh out of barrels is lowered to a temperature a few degrees below freezing – a state where the haze-producing compounds will thicken and clump together. The mixture of the still liquid whisky and the clumped sediments is then passed through a series of absorption filters (metal, crushed seashells and paper) designed to trap all material larger than a few microns. The number and types of the absorption filters, the pressure applied and the speed at which the whisky is flown through them determines how much of the sediment is removed from the final product.

The video below shows the paper filters and explains the process further.

 What types of whisky are chill filtered?

As mentioned above, chill filtration is usually applied to remove the possibility of a haze build-up when you chill down whiskies that have ABV levels lower than 46%. Since the decision boils down to aesthetics, the approach among distillers vary.

Not many distillers chill filter whiskeys above 46% ABV and even fewer apply chill filtration to those above 50% ABV. In general, this will mean that lower proof whiskeys, such as blended scotches, bourbons and sour mash, are more likely to be chill filtered, while stronger single malt Scotches are unlikely to be finished that way. However, there are exceptions. Some distilleries do chill filter many or all of their expressions, even those at higher ABVs. More on that below.

The opposite case is also true. While most distilleries tend to chill filter whiskies that are less than 92 Proof (46% ABV), there are some that offer non-chill filtered whiskies at between 42-46% ABV.

What effect on flavour and taste does chill filtration have?

This is a topic of hot debate between people who do pay attention to whether their whisky is chill filtered. First, the obvious. Chill filtration for whiskies that are less than 46% ABVs will remove the possibility of the haze or cloudiness that would normally occur when the drinks are chilled. Ergo, chill filtration produces a bright, clear whisky on the rocks.

Even premium distillers sometimes pay homage to the distinction between a clear and cloudy drink. One thing that’s clear is that the compounds do not create the haze if the strength is higher than 46% ABV. The smokiness is created by what is known as reversible flocculation (“floc”). At higher strengths, the floc cannot form.

For example, there is the famous story of  Burn Stewart’s master blender, Ian McMillan, who persuaded the distillery to raise the strength of its Bunnahabhain, Deanston, Tobermory and Ledaig single malt Scotch whiskies to 46.3% ABV – in order to save their having to go through the chill filtration process.

However, that is not the whole story …

Why is chill filtration a point of contention? Does it alter the taste, flavour and aromas?

In his passionate condemnation of chill filtration, McMillan spoke of the “oily and greasy” residues, rich in aroma and flavour, that had been built up through the distillation process and mixed in with the sediment flavors from the cask. This forms the crux of the matter. Purists argue that chill filtering robs the whisky of the floc which in fact contributes to the flavor, texture, aroma and “mouthful” – an essential part of the experience to serious drinkers who prefer to sip their whisky, rolling it around their tongue and savoring the taste on their palate.

Having said that, scientists are decidedly skeptical on whether or not chill filtration can substantially alter any of the flavor or aroma in whisky. Double tasting studies conducted with scotch whisky experts have proved inconclusive. If any effects are produced, they are minimal and nowhere near as pronounced as the effect on color and clarity – that is, how chill filtering brightens the color by clearing up the haze in chilled whisky. Skeptics also point out that even some of the absolute best whiskies, such as _Lagavulin 16_, have artificial coloring mixed in – certainly the effect of chill filtering would be much less pronounced than that.

But for serious drinkers of high-end Scotches, this is a debate worth having.

Another catch

One final thing to remember is that whisky which is above 46% ABV, but not by much, can easily be brought down to the concentration threshold by adding water. The threshold only works if the strength remains at 46% ABV or higher when you drink.

Examples of chill and non chill filtered brands

As mentioned above, many distilleries prefer not to use chill filtration, or the lack thereof, on their labels. However, some specific labels are well known.

Commonly chill filtered brands

Among the common brands that are filtered are popular US bourbon whiskey brands such as Jack Daniels, Wild Turkey, Woodford Reserve (paper filtered only) and Knob Creek, all of which chill filter their low proof offerings. Another distillery, Michter, chill filters all of their offerings regardless of their ABV. Some well known single malt brands chill filter offerings that are close to or below 46% ABV – examples include Talisker and Macallan.

Brands that never chill filter

Whiskeys that remain non-chill filtered are considerably larger in number, especially among the higher-end single malt Scotches and good Bourbon producing distilleries. In addition to the Burn Stewart offerings mentioned above, other examples include brands such as Aberlour, Bruichladdich, Arran, Ardbeg, Laphroig, Oban, Springbank and Glenfarclass among single malts. A number of bourbons also offer non-chill factored whiskey, including Makers Mark, Four Roses, New Riff and Bulleit among commonly found brands.

The final verdict

Non-chill factored has become a marketing slogan for high-end whiskies, whether or not there is, in fact, any proven difference in taste, texture, flavour or aroma. If you belong to the group of enthusiasts that prefer purity in everything whisky-related, scan the labels or check with your favourite brand distillery to assure yourself that you are not buying chill filtered whisky. If, instead, you want a clear, bright whisky regardless of its strength, get a brand that does advertise a chill filtered offering.