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Fib of the Week #10: “If my whisky looks cloudy, that means it’s off!”

It’s that time again, our and hopefully your favourite feature of the week, #FibFriday! For this week, Aedan will be looking at an excuse a lot of big companies use for chill-filtration, because people fear - Fib of the Week #10: “If my whisky looks cloudy, that means it’s off!”. 😱

Have you ever noticed your whisky suddenly go cloudy, particularly if you add water or ice to a dram, particularly over 46.3% ABV? Don’t worry, this is natural and is meant to happen, as cooling helps separate some of the chemical compounds, particularly the oils and fatty acids which provide a lot of the flavour and particularly contribute to mouthfeel. All that is happening here is that these are precipitating out slightly, thus becoming more visible in the glass. Alcohol over certain percentages, including a 40% ABV, is a good disinfectant and will kill almost anything. Similarly, it makes a great preserving agent. Shackleton’s whisky semi-recently rediscovered in the Antarctic after nearly 100 years was probably still good to drink - it was certainly still good for chemical analysis, which is part of why we have the brand today - just no one wanted to drink such a historical artefact (yet). It’s very, very difficult for spirits to go off - hence no use by date or best before, hence people drinking heirloom bottles from decades and even over a century ago and showing off on social media (we’re just jealous). It’s perfectly safe, as is haze. A bit of cloudiness in your whisky is just fine, even a good sign. Hell, one of our favourite bottles of all time, a single cask Auchentoshan from near the end of the barrel, was full of floaters, for gods’ sake, mainly little bits of char. And that just added to the brilliance. Not that we’re saying that all floaters are good… 😂

Before bottling, pretty much all whisky will go through a simple paper and/or metal filtration process, basically like a simple coffee filter, although there are many different actual designs. That’s why, unless you are bottling with a valinch from the actual cask, and that when the cask is quite empty, you shouldn’t have any obvious particulate contaminants (posh term for visible floaty bits, including charcoal). Among particularly the big brands selling in supermarkets, however, there is a fear that consumers will be put off if there whisky doesn’t remain crystal clear under any condition - cold, warm, water or no water. And supermarkets or the brand sometimes get complaints from concerned consumers. That’s why a lot of the big companies reduce the ABV below 46.3% ABV and put the spirit through a process called chill-filtration. Both are forms of essentially sieve filtration as opposed to powder filtration sometimes used for beer, which we don’t need to worry about here. Essentially, the whisky is reduced to temperatures between -5-10°C, causing certain fatty acids, oils and proteins, along with some esters (our fruity flavour compounds 😱), to precipitate out of suspension. Filtration then occurs, removing these substances which might cause haze as well as preventing any sediment from forming later in the bottle. The process has become less popular as it has become more known by the consumer base, for fear that it strips out a good number of flavour molecules and definitely reduces mouthfeel. Spirits above 46.3% ABV are less effectively chill-filtered, and especially spirits above 50% ABV. Anything above these percentages is therefore very rarely chill-filtered by the Scotch industry, although some American bourbons do chill-filter everything they release. Debates about the effect on flavour are honestly inconclusive, but losing fatty acids and oils definitely reduces mouthfeel, and we like many whisky fans consider it a process to be avoided. After all, we love our spirit. Why shouldn’t we be allowed to enjoy it the way it naturally comes? Who cares about haze.

The fact is, as mentioned above, it’s pretty hard to make whisky go off. It’s just too high in alcohol content, which should stay the same in bottle, even after many years. A couple of unofficial experiments have been undertaken on what might change the flavour of a bottle of whisky, for example to see if any further maturation is possible outside of the cask. However, outside of strapping your whisky to the back of your tumble dryer or washing machine (yes, it’s been done - for science!), there should be very little flavour change, and practically no chance of spoilage in whisky stored at ambient room temperatures. (And yes, interestingly, intense heat from being strapped to a washing machine in a hot utility room did indeed mimic the effects of further ageing on a sherried dram, the unofficial study showed. We recommend ageing in cask in a warehouse, however.). Once the bottle is opened, there are obviously other factors to content with - namely oxidation once that seal has been broken and more importantly once there is more air in the bottle, in direct contact with the spirit. You can imagine, for example, that the surface area contact on a spirits bottle at neck fill is relatively low compared to the contact zone once the bottle is a bit emptier. Many people report reduced flavour from oxidation after more than about 6 months of the bottle being open - not off notes per se, just the sort of flatness and reduction of flavour intensity - but this is not something we have ever noted ourselves, unless a bottle was particularly empty, and we mean below 10%. And logically, it shouldn’t, because unless a bottle is actively agitated to mix the remaining spirit with air, the potential surface area for oxidation should be the same at 90%, or indeed anywhere below neck fill, as at 5% - a flat circle measuring the surface area of the base of the bottle. Because of the risk of oxidation, many people recommend trying to finish your bottle within 6 months of opening anyway, and this may be fair, but we wouldn’t think of it as a hard and fast rule. Your whisky would not be off anyway. It just might not taste quite as good.

Much more problematic than oxidation or basic storage temperature, however, is the risk of sun taint. It is widely accepted and endorsed by the SWA that storage in direct sunlight is unwise. UV light is thought to break down compounds within the whisky, resulting not just in less intense flavour and/or colour, but also off, rubbery notes. This is heavily backed by both official and unofficial studies, where in anecdotal tastings that unpleasant flavour has been noted as markedly obvious. Is the whisky still safe to drink? Yes. Is it still nice, though? Really rather no. Like a painting or even your favourite label, the spirit will become faded and less fun. Worse than pristine artworks, it will also become actively flawed. If you wouldn’t store that stolen Rembrandt in front a window in direct sun, don’t store your whisky masterpieces there either.

So stored right, your whisky can’t go off. Sure, some people recommend you drink it within a certain timeframe, but it’s not obligatory. Do not store whisky in direct sunlight. And regarding a bit of cloudiness or haze, hell even some floating bits of charcoal? Those actively make the whisky better. So go ahead, pour a hazy dram and enjoy. Slàinte! 🥃


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